Patent Grant
10058064
One goal of plant breeding is to combine, in a single hybrid or variety, various desirable traits. For field crops, these traits may include resistance to diseases and insects, resistance to heat and drought, reducing the time to crop maturity, greater yield, and better agronomic quality. Uniformity of plant characteristics such as germination and stand establishment, growth rate, maturity, plant height and fruit size facilitates mechanical harvesting. Traditional plant breeding through the development and use of inbred varieties facilitates the development of new and improved commercial crops.
According to the present invention, there is provided a novel sorghum line designated PH2307GR. This invention relates to seed of sorghum line PH2307GR, to the plants of sorghum line PH2307GR, to plant parts of sorghum line PH2307GR, and to processes for making a plant that comprise crossing sorghum line PH2307GR with another plant. This invention also relates to processes for making a plant containing in its genetic material one or more traits introgressed into PH2307GR through backcross conversion and/or transformation, and to the seed, plant and plant arts produced thereby. This invention further relates to a hybrid seed, plant, or plant part produced by crossing the line PH2307GR or a locus conversion of PH2307GR with another plant.
In the description and examples that follow, a number of terms are used herein. In order to provide a clear and consistent understanding of the specification and claims, including the scope to be given such terms, the following definitions are provided:
Anthracnose Resistance. This is a visual rating based on the number of lesions caused by anthracnose infection. A score of 9 would indicate little necrosis and a score of 1 would indicate plant death as a result of anthracnose infection.
Bacterial Spot. Bacterial Spot is a disease characterized by small, irregularly shaped lesions on the leaves. Bacterial Spot Resistance is rated on a scale of 1 to 9, with 1 being susceptible and 9 being resistant.
Bacterial Streak. Bacterial Streak is a disease characterized by narrow yellow stripes on the leaves. Bacterial Streak Resistance is rated on a scale of 1 to 9, with 1 being susceptible and 9 being resistant.
Bacterial Stripe. Bacterial Stripe is a disease characterized by long, narrow red stripes on the leaves. Bacterial Stripe Resistance is rated on a scale of 1 to 9, with 1 being susceptible and 9 being resistant.
Biotype C Greenbug Resistance. This is a visual rating based on the amount of necrosis on leaves and stems caused by biotype C greenbug feeding. A score of 9 would indicate no leaf or stem damage as a result of greenbug feeding.
Biotype E Greenbug Resistance. This is a visual rating based on plant seedlings ability to continue growing when infested with large numbers of biotype E greenbugs. A score of 9 indicates normal growth and a score of 1 indicates seedling death. Charcoal Rot. Charcoal Rot is a disease characterized by rotting of the roots and stalks. Charcoal Rot Resistance is rated on a scale of 1 to 9, with 1 being susceptible and 9 being resistant.
Chinch Bug Resistance. This is a visual rating based on the plants ability to grow normally when infested with large numbers of chinch bugs. A score of 9 would indicate normal growth and a score of 1 would indicate severe plant stunting and death.
Crop Response to Herbicide. Rated as the visual difference between sprayed and un-sprayed plants. A crop response of less than 30% means no visual difference, higher percentages means sprayed plants showed some damage.
Days to Color. The days to color is the number of days required for an inbred line or hybrid to begin grain coloring from the time of planting. Coloring of the grain is correlated with physiological maturity, thus days to color gives an estimate of the period required before a hybrid is ready for harvest.
Days to Flower. The days to flower is the number of days required for an inbred line or hybrid to shed pollen from the time of planting.
Downy Mildew Resistance (Pathotypes 1, 3, and 6). This is a visual rating based on the percentage of downy mildew infected plants. A score of 9 indicates no infected plants. A score of 1 would indicate higher than 50% infected plants. Ratings are made for infection by each pathotype of the disease.
Drought Tolerance. This represents a rating for drought tolerance and is based on data obtained under stress. It is based on such factors as yield, plant health, lodging resistance and stay green. A high score would indicate a hybrid tolerant to drought stress.
Dry Down. This represents the relative rate at which a plant will reach acceptable harvest moisture compared to other plants. A high score indicates a plant that dries relatively fast while a low score indicates a plant that dries slowly.
Fusarium Root and Stalk Rot. Fusarium Root and Stalk Rot is a disease characterized by rotting of the roots and stalks. Fusarium Root and Stalk Rot Resistance is rated on a scale of 1 to 9, with 1 being susceptible and 9 being resistant.
Grain Mold. Grain Mold is characterized by the formation of mold on heads and grain. Grain Mold Resistance is rated on a scale of 1 to 9, with 1 being susceptible and 9 being resistant.
Gray Leaf Spot Resistance. This is a visual rating based on the number of gray leaf spot lesions present on the leaves and stem of the plant. A score of 9 would indicate the presence of few lesions.
Head Exertion. This represents a rating for the length of the peduncle exposed between the base of the panicle (head) and the flag leaf of the plant. A high score indicates more distance between the flag leaf and the sorghum head while a low score indicates a short distance between the two. Head exertion facilitates ease of combine harvesting.
Head Smut Resistance (Races 1-5). This is a visual rating based on the percentage of smut infected plants. A score of 9 would indicate no infected plants and a score of 1 would indicate higher than 50% infected plants. Ratings are made for each race of head smut.
Head Type. This represents a rating of the morphology of the sorghum panicle (head). A high score indicates an open panicle caused by either more distance between panicle branches or longer panicle branches. A low score indicates a more compact panicle caused by shorter panicle branches arranged more closely on the central rachis.
Leaf Burn Resistance. This is a visual rating based on the amount of tissue damage caused by exposure to insecticide sprays. A score of 9 would indicate minor leaf spotting and a score of 1 would indicate leaf death as a result of contact with insecticide spray.
Locus Conversion (Also called a Trait Conversion): A locus conversion refers to a modified plant within a variety that retains the overall genetics of the variety and further includes a locus with one or more specific desired traits, and otherwise has the same, essentially the same, all or essentially all of the physiological and morphological characteristics of the variety, such as listed in Table 1. Traits can be directed to, for example, modified grain, male sterility, insect control, disease control or herbicide tolerance. Traits can be mutant genes, transgenic sequences or native traits. A single locus conversion refers to plants within a variety that have been modified in a manner that retains the overall genetics of the variety and include a single locus with one or more specific desired traits. A single locus conversion can include at least or about 1, 2, 3, 4 or 5 traits and less than or about 15, 10, 9, 8, 7 or 6 traits. A locus converted plant can include, for example, at least or about 1, 2 or 3 and less than or about 20, 15, 10, 9, 8, 7, 6, or 5 modified loci while still retaining the overall genetics of the variety and otherwise having essentially the same, the same, all or essentially all of the physiological and morphological characteristics of the variety, such as listed in Table 1. The total number of traits at one or more locus conversions can be, for example, at least or about 1, 2, 3, 4 or 5 and less than or about 25, 20, 15, 10, 9, 8, 7 or 6. Examples of single locus conversions include mutant genes, transgenes and native traits finely mapped to a single locus. Traits may be introduced by transformation, backcrossing, or a combination of both.
Maize Dwarf Mosaic Virus Resistance. This is a visual rating based on the percentage of sorghum plants showing symptoms of virus infection. A score of 9 would indicate no plants with virus symptoms and a 1 would indicate a high percentage of plants showing symptoms of virus infection such as stunting, red leaf symptoms or leaf mottling.
Midge Resistance. This is a visual rating based on the percentage of seed set in the panicle in the presence of large numbers of midge adults. A score of 9 would indicate near normal seed set and a score of 1 would indicate no seed set in the head due to midge damage.
Moisture. The moisture is the actual percentage moisture of the grain at harvest.
Percent Yield. The percent yield is the yield obtained from the hybrid in terms of percent of the mean for the experiment in which it was grown.
Plant: As used herein, the term “plant” includes reference to an immature or mature whole plant, including a plant from which seed or grain has been removed.
Plant Height. This is a measure of the average height of the hybrid from the ground to the tip of the panicle and is measured in inches.
Plant Part: As used herein, the term “plant part” includes leaves, stems, roots, seed, grain, kernels, panicles, embryo, pollen, ovules, flowers, stalks, root tips, anthers, pericarp, protoplasts, tissue, plant calli, cells and the like. In some embodiments the plant part contains at least one cell of sorghum variety PH2307GR.
Predicted RM. This trait, predicted relative maturity (RM), for a hybrid is based on the number of days required for an inbred line or hybrid to shed pollen from the time of planting. The relative maturity rating is based on a known set of checks and utilizes standard linear regression analyses.
Puccinia (Rust) Resistance. This is a visual rating based on the number of rust pustules present on the leaves and stem of the plant. A score of 9 would indicate the presence of few rust pustules. RM to Color. This trait for a hybrid is based on the number of days required for a hybrid to begin to show color development in the grain from the time of planting. The relative maturity rating is based on a known set of checks and utilizes standard linear regression analyses.
Root Lodging. This represents a rating of the percentage of plants that do not root lodge, i.e. those that lean from the vertical axis at an approximate 30 degree angle or greater without stalk breakage are considered to be root lodged. This is a relative rating of a hybrid to other hybrids for standability. Root lodging is rated on a scale of 1 to 9, with 1 indicating greater than 50% lodged plants and 9 indicating no lodged plants.
Sales Appearance. This represents a rating of the acceptability of the hybrid in the market place. It is a complex score including such factors as hybrid uniformity, appearance of yield, grain texture, grain color and general plant health. A high score indicates the hybrid would be readily accepted based on appearance only. A low score indicates hybrid acceptability to be marginal based on appearance only.
Salt Tolerance. This represents a rating of the plants ability to grow normally in soils having high sodium salt content. This is a relative rating of a hybrid to other hybrids for normal growth.
Selection Index. The selection index gives a single measure of the hybrid's worth based on information for up to five traits. A sorghum breeder may utilize his or her own set of traits for the selection index. Two of the traits that are almost always included are yield and days to flower (maturity). The selection index data presented in the tables in the specification represent the mean values averaged across testing stations.
Sooty Stripe. Sooty Stripe is a disease characterized by elongate, elliptical lesions on the leaves. Sooty Stripe Resistance is rated on a scale of 1 to 9, with 1 being susceptible and 9 being resistant. Stalk Lodging. This represents a rating of the percentage of plants that do not stalk lodge, i.e. stalk breakage above the ground caused by natural causes. This is a relative rating of a hybrid to other hybrids for standability. Stalk lodging is rated on a scale of 1 to 9, with 1 indicating greater than 50% lodged plants and 9 indicating no lodged plants.
Stay Green. Stay green is the measure of plant health near the time of harvest. A high score indicates better late-season plant health.
Test Weight. This is the measure of the weight of the grain in pounds for a given volume (bushel) adjusted for percent moisture.
Weathering. This represents a rating of how well the exposed grains are able to retain normal seed quality when exposed to normal weather hazards and surface grain molds. Yield (cwt/acre). The yield in cwt/acre is the actual yield of the grain at harvest adjusted to 13% moisture.
Yield/RM. This represents a rating of a hybrid yield compared to other hybrids of similar maturity or RM. A high score would indicate a hybrid with higher yield than other hybrids of the same maturity.
Yield Under Stress. This is a rating of the plants ability to produce grain under heat and drought stress conditions. A score of 9 would indicate near normal growth and grain yield and a score of 1 would indicate substantial yield reduction due to stress.
Zonate Leaf Spot Resistance. This is a visual rating based on the number of zonate leaf spot lesions present on the leaves and stem of the plant. A score of 9 would indicate the presence of few lesions.
Field crops are bred through techniques that take advantage of the plant's method of pollination. A plant is self-pollinating if pollen from one flower is transferred to the same or another flower of the same plant. A plant is cross-pollinated if the pollen comes from a flower on a different plant.
Plants that have been self-pollinated and selected for type for many generations become homozygous at almost all gene loci and produce a uniform population of true breeding progeny. A cross between two homozygous plants from differing backgrounds or two homozygous lines produce a uniform population of hybrid plants that may be heterozygous for many gene loci. A cross of two plants that are each heterozygous at a number of gene loci will produce a population of hybrid plants that differ genetically and will not be uniform.
Sorghum plants (Sorghum bicolor L. Moench) are bred in most cases by self-pollination techniques. With the incorporation of male sterility (either genetic or cytoplasmic) cross pollination breeding techniques can also be utilized. Sorghum has both male and female parts in the same flower located in the panicle. The flowers are usually in pairs on the panicle branches. Natural pollination occurs in sorghum when anthers (male flowers) open and pollen falls onto receptive stigma (female flowers). Because of the close proximity of male (anthers) and female (stigma) in the panicle, self-pollination is very high (average 94%). Cross pollination may occur when wind or convection currents move pollen from the anthers of one plant to receptive stigma on another plant. Cross pollination is greatly enhanced with incorporation of male sterility which renders male flowers nonviable without affecting the female flowers. Successful pollination in the case of male sterile flowers requires cross pollination.
Sorghum is in the same family as maize and has a similar growth habit, but with more tillers and a more extensively branched root system. Sorghum is more drought resistant and heat-tolerant than maize. It requires an average temperature of at least 25° C. to produce maximum yields. Sorghum's ability to thrive with less water than maize may be due to its ability to hold water in its foliage better than maize. Sorghum has a waxy coating on its leaves and stems which helps to keep water in the plant even in intense heat. Wild species of sorghum tend to grow to a height of 1.5 to 2 meters; to improve harvestability, dwarfing genes have been selected in cultivated varieties and hybrids such that most cultivated varieties and hybrids grow to 60 and 120 cm tall.
Inbred Development
The development of sorghum hybrids requires the development of homozygous inbred lines, the crossing of these lines, and the evaluation of the crosses. Pedigree breeding methods, and to a lesser extent population breeding methods, are used to develop inbred lines from breeding populations. Breeding programs combine desirable traits from two or more inbred lines into breeding pools from which new inbred lines are developed by selfing and selection of desired phenotypes. The new inbreds are crossed with other inbred lines and the hybrids from these crosses are evaluated to determine which have commercial potential.
Pedigree breeding starts with the crossing of two genotypes, each of which may have one or more desirable characteristics that is lacking in the other or which complement the other. If the two original parents do not provide all of the desired characteristics, other sources can be included in the breeding population. In the pedigree method, superior plants are selfed and selected in successive generations. In the succeeding generations the heterozygous condition gives way to homogeneous lines as a result of self-pollination and selection. Typically, in the pedigree method of breeding five or more generations of selfing and selection is practiced. F1 to F2; F2 to F3; F3 to F4, F4 to F5, etc.
Backcrossing can be used to improve an inbred line. Backcrossing transfers a specific desirable trait from one inbred or source to an inbred that lacks that trait. This can be accomplished for example by first crossing a superior inbred (A) (recurrent parent) to a donor inbred (non-recurrent parent), which carries the appropriate genes(s) for the trait in question. The progeny of this cross is then mated back to the superior recurrent parent (A) followed by selection in the resultant progeny for the desired trait to be transferred from the non-recurrent parent. After five or more backcross generations with selection for the desired trait, the progeny will be heterozygous for loci controlling the characteristic being transferred, but will be like the superior parent for most or almost all other genes. The last backcross generation would be selfed to give pure breeding progeny for the gene(s) being transferred.
Controlling Self-Pollination
Sorghum varieties are mainly self-pollinated; therefore, self-pollination of the parental varieties must be controlled to make hybrid development feasible. A pollination control system and effective transfer of pollen from one parent to the other offers improved plant breeding and an effective method for producing hybrid seed and plants. For example, the milo or A1 cytoplasmic male sterility (CMS) system, developed via a cross between milo and kafir cultivars, is one of the most frequently used CMS systems in hybrid sorghum production (Stephens JC & Holland PF, Cytoplasmic Male Sterility for Hybrid Sorghum Seed Production, Agron. J. 46:20-23 (1954)). Other CMS systems for sorghum include, but are not limited to, A2, isolated from IS 12662c (Schertz KF, Registration of A2Tx 2753 and BTX 2753 Sorghum Germplasm, Crop Sci. 17: 983 (1977)), A3, isolated from IS 1112c or converted Nilwa (Quinby JR, Interactions of Genes and Cytoplasms in Male-Sterility in Sorghums, Proc. 35th Corn Sorghum Res. Conf. Am. Seed Trade Assoc. Chicago, III., pp. 5-8 (1980)), A4, isolated from IS 7920c (Worstell et al, Relationship among Male-Sterility Inducing Cytoplasms of Sorghum, Crop Sci. 24:186-189 (1984)).
In developing improved new sorghum hybrid varieties, breeders may use a CMS plant as the female parent. In using these plants, breeders attempt to improve the efficiency of seed production and the quality of the F1 hybrids and to reduce the breeding costs. When hybridization is conducted without using CMS plants, it is more difficult to obtain and isolate the desired traits in the progeny (F1 generation) because the parents are capable of undergoing both cross-pollination and self-pollination. If one of the parents is a CMS plant that is incapable of producing pollen, only cross pollination will occur. By eliminating the pollen of one parental variety in a cross, a plant breeder is assured of obtaining hybrid seed of uniform quality, provided that the parents are of uniform quality and the breeder conducts a single cross.
In one instance, production of F1 hybrids includes crossing a CMS female parent with a pollen-producing male parent. To reproduce effectively, however, the male parent of the F1 hybrid must have a fertility restorer gene (Rf gene). The presence of an Rf gene means that the F1 generation will not be completely or partially sterile, so that either self-pollination or cross pollination may occur. Self-pollination of the F1 generation to produce several subsequent generations is important to ensure that a desired trait is heritable and stable and that a new variety has been isolated.
Promising advanced breeding lines commonly are tested and compared to appropriate standards in environments representative of the commercial target area(s). The best lines are candidates for new commercial lines; and those still deficient in a few traits may be used as parents to produce new populations for further selection.
Hybrid Development
A hybrid sorghum variety is the cross of two inbred lines, each of which may have one or more desirable characteristics lacked by the other or which complement the other. The hybrid progeny of the first generation is designated F1. In the development of hybrids only the F1 hybrid plants are sought. The F1 hybrid is more vigorous than its inbred parents. This hybrid vigor, or heterosis, can be manifested in many ways, including increased vegetative growth and increased yield.
The development of a hybrid sorghum variety involves five steps: (1) the formation of “restorer” and “non-restorer” germplasm pools; (2) the selection of superior plants from various “restorer” and “non-restorer” germplasm pools; (3) the selfing of the superior plants for several generations to produce a series of inbred lines, which although different from each other, each breed true and are highly uniform; (4) the conversion of inbred lines classified as non-restorers to cytoplasmic male sterile (CMS) forms, and (5) crossing the selected cytoplasmic male sterile (CMS) inbred lines with selected fertile inbred lines (restorer lines) to produce the hybrid progeny (F1).
Because sorghum is normally a self-pollinated plant and because both male and female flowers are in the same panicle, large numbers of hybrid seed can only be produced by using cytoplasmic male sterile (CMS) inbreds. Flowers of the CMS inbred are fertilized with pollen from a male fertile inbred carrying genes which restore male fertility in the hybrid (F1) plants. An important consequence of the homozygosity and homogeneity of the inbred lines is that the hybrid between any two inbreds will always be the same. Once the inbreds that produce the best hybrid have been identified, the hybrid seed can be reproduced indefinitely as long as the homogeneity of the inbred parent is maintained.
A single cross hybrid is produced when two inbred lines are crossed to produce the F1 progeny. Much of the hybrid vigor exhibited by F1 hybrids is lost in the next generation (F2). Consequently, seed from hybrid varieties is not used for planting stock.
Hybrid grain sorghum can be produced using wind to move the pollen. Alternating strips of the cytoplasmic male sterile inbred (female) and the male fertile inbred (male) are planted in the same field. Wind moves the pollen shed by the male inbred to receptive stigma on the female. Providing that there is sufficient isolation from sources of foreign sorghum pollen, the stigma of the male sterile inbred (female) will be fertilized only with pollen from the male fertile inbred (male). The resulting seed, born on the male sterile (female) plants is therefore hybrid and will form hybrid plants that have full fertility restored.
Genotypic Characteristics of Variety PH2307GR
In addition to phenotypic observations, a plant can also be described or identified by its genotype. The genotype of a plant can be characterized through a genetic marker profile. Genetic marker profiles can be obtained by techniques such as Restriction Fragment Length Polymorphisms (RFLPs), Randomly Amplified Polymorphic DNAs (RAPDs), Arbitrarily Primed Polymerase Chain Reaction (AP-PCR), DNA Amplification Fingerprinting (DAF), Sequence Characterized Amplified Regions (SCARs), Amplified Fragment Length Polymorphisms (AFLPs), Simple Sequence Repeats (SSRs) which are also referred to as Microsatellites, and Single Nucleotide Polymorphisms (SNPs).
Particular markers used for these purposes may include any type of marker and marker profile which provides a means of distinguishing varieties. A genetic marker profile can be used, for example, to identify plants of the same variety or related varieties or to determine or validate a pedigree. In addition to being used for identification of sorghum variety PH2307GR and its plant parts, the genetic marker profile is also useful in developing a locus conversion of PH2307GR.
Methods of isolating nucleic acids from sorghum plants and methods for performing genetic marker profiles using SNP and SSR polymorphisms are well known in the art. SNPs are genetic markers based on a polymorphism in a single nucleotide. A marker system based on SNPs can be highly informative in linkage analysis relative to other marker systems in that multiple alleles may be present.
A method comprising isolating nucleic acids, such as DNA, from a plant, a plant part, plant cell or a seed of the sorghum plants disclosed herein is provided. The method can include mechanical, electrical and/or chemical disruption of the plant, plant part, plant cell or seed, contacting the disrupted plant, plant part, plant cell or seed with a buffer or solvent, to produce a solution or suspension comprising nucleic acids, optionally contacting the nucleic acids with a precipitating agent to precipitate the nucleic acids, optionally extracting the nucleic acids, and optionally separating the nucleic acids such as by centrifugation or by binding to beads or a column, with subsequent elution, or a combination thereof. If DNA is being isolated, an RNase can be included in one or more of the method steps. The nucleic acids isolated can comprise all or substantially all of the genomic DNA sequence, all or substantially all of the chromosomal DNA sequence or all or substantially all of the coding sequences (cDNA) of the plant, plant part, or plant cell from which they were isolated. The amount and type of nucleic acids isolated may be sufficient to permit whole genome sequencing of the plant from which they were isolated or chromosomal marker analysis of the plant from which they were isolated.
The methods can be used to produce nucleic acids from the plant, plant part, seed or cell, which nucleic acids can be, for example, analyzed to produce data. The data can be recorded. The nucleic acids from the disrupted cell, the disrupted plant, plant part, plant cell or seed or the nucleic acids following isolation or separation can be contacted with primers and nucleotide bases, and/or a polymerase to facilitate PCR sequencing or marker analysis of the nucleic acids. In some examples, the nucleic acids produced can be sequenced or contacted with markers to produce a genetic profile, a molecular profile, a marker profile, a haplotype, or any combination thereof. In some examples, the genetic profile or nucleotide sequence is recorded on a computer readable medium. In other examples, the methods may further comprise using the nucleic acids produced from plants, plant parts, plant cells or seeds in a plant breeding program, for example in making crosses, selection and/or advancement decisions in a breeding program. Crossing includes any type of plant breeding crossing method, including but not limited to crosses to produce hybrids, outcrossing, selfing, backcrossing, locus conversion, introgression and the like. Favorable genotypes and or marker profiles, optionally associated with a trait of interest, may be identified by one or more methodologies. In some examples one or more markers are used, including but not limited to AFLPs, RFLPs, ASH, SSRs, SNPs, indels, padlock probes, molecular inversion probes, microarrays, sequencing, and the like. In some methods, a target nucleic acid is amplified prior to hybridization with a probe. In other cases, the target nucleic acid is not amplified prior to hybridization, such as methods using molecular inversion probes. In some examples, the genotype related to a specific trait is monitored, while in other examples, a genome-wide evaluation including but not limited to one or more of marker panels, library screens, association studies, microarrays, gene chips, expression studies, or sequencing such as whole-genome resequencing and genotyping-by-sequencing (GBS) may be used. In some examples, no target-specific probe is needed, for example by using sequencing technologies, including but not limited to next-generation sequencing methods (see, for example, Metzker (2010) Nat Rev Genet 11:31-46; and, Egan et al. (2012) Am J Bot 99:175-185) such as sequencing by synthesis (e.g., Roche 454 pyrosequencing, Illumina Genome Analyzer, and Ion Torrent PGM or Proton systems), sequencing by ligation (e.g., SOLiD from Applied Biosystems, and Polnator system from Azco Biotech), and single molecule sequencing (SMS or third-generation sequencing) which eliminate template amplification (e.g., Helicos system, and PacBio RS system from Pacific BioSciences). Further technologies include optical sequencing systems (e.g., Starlight from Life Technologies), and nanopore sequencing (e.g., GridION from Oxford Nanopore Technologies). Each of these may be coupled with one or more enrichment strategies for organellar or nuclear genomes in order to reduce the complexity of the genome under investigation via PCR, hybridization, restriction enzyme, and expression methods. In some examples, no reference genome sequence is needed in order to complete the analysis. Variety PH2307GR and its plant parts can be identified through a molecular marker profile. Such plant parts may be either diploid or haploid. The plant part includes at least one cell of the plant from which it was obtained, such as a diploid cell, a haploid cell or a somatic cell. Also provided are plants and plant parts substantially benefiting from the use of variety PH2307GR in their development, such as variety PH2307GR comprising a locus conversion.
Locus Conversions of Sorghum Line PH2307GR
PH2307GR represents a new base genetic line into which a new locus or trait may be introduced. Direct transformation and backcrossing represent two important methods that can be used to accomplish such an introgression. The term locus conversion is used to designate the product of such an introgression.
To select and develop a superior hybrid, it is necessary to identify and select genetically unique individuals that occur in a segregating population. The segregating population is the result of a combination of crossover events plus the independent assortment of specific combinations of alleles at many gene loci that results in specific and unique genotypes. Once such a variety is developed its value to society is substantial since it is important to advance the germplasm base as a whole in order to maintain or improve traits such as yield, disease resistance, pest resistance and plant performance in extreme weather conditions. Locus conversions are routinely used to add or modify one or a few traits of such a line and this further enhances its value and usefulness to society.
Backcrossing can be used to improve inbred varieties and a hybrid variety which is made using those inbreds. Backcrossing can be used to transfer a specific desirable trait from one variety, the donor parent, to an inbred called the recurrent parent which has overall good agronomic characteristics yet that lacks the desirable trait. This transfer of the desirable trait into an inbred with overall good agronomic characteristics can be accomplished by first crossing a recurrent parent to a donor parent (non-recurrent parent). The progeny of this cross is then mated back to the recurrent parent followed by selection in the resultant progeny for the desired trait to be transferred from the non-recurrent parent.
Traits may be used by those of ordinary skill in the art to characterize progeny. Traits are commonly evaluated at a significance level, such as a 1%, 5% or 10% significance level, when measured in plants grown in the same environmental conditions. For example, a locus conversion of PH2307GR may be characterized as having essentially the same phenotypic traits as PH2307GR. The traits used for comparison may be those traits shown in Table 1. Molecular markers can also be used during the breeding process for the selection of qualitative traits. For example, markers can be used to select plants that contain the alleles of interest during a backcrossing breeding program. The markers can also be used to select for the genome of the recurrent parent and against the genome of the donor parent. Using this procedure can minimize the amount of genome from the donor parent that remains in the selected plants.
A locus conversion of PH2307GR will retain the genetic integrity of PH2307GR. A locus conversion of PH2307GR will comprise at least 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% of the base genetics of PH2307GR. For example, a locus conversion of PH2307GR can be developed when DNA sequences are introduced through backcrossing (Hallauer et al., 1988), with a parent of PH2307GR utilized as the recurrent parent. Both naturally occurring and transgenic DNA sequences may be introduced through backcrossing techniques. A backcross conversion may produce a plant with a locus conversion in at least one or more backcrosses, including at least 2 crosses, at least 3 crosses, at least 4 crosses, at least 5 crosses and the like. Molecular marker assisted breeding or selection may be utilized to reduce the number of backcrosses necessary to achieve the backcross conversion. For example, see Openshaw, S.J. et al., Marker-assisted Selection in Backcross Breeding. In: Proceedings Symposium of the Analysis of Molecular Data, August 1994, Crop Science Society of America, Corvallis, Oreg., where it is demonstrated that a backcross conversion can be made in as few as two backcrosses. A locus conversion of PH2307GR can be determined through the use of a molecular profile. A locus conversion of PH2307GR would have 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% of the molecular markers, or molecular profile, of PH2307GR. Examples of molecular markers that could be used to determine the molecular profile include Restriction Fragment Length Polymorphisms (RFLP), Polymerase Chain Reaction (PCR) analysis, and Simple Sequence Repeats (SSR), and Single Nucleotide Polymorphisms (SNPs).
Genetic Modification and Transformation of Sorghum Line PH2307GR
Transgenes, genetic editing or modification and transformation methods facilitate engineering of the genome of plants to contain and express heterologous genetic elements, such as foreign genetic elements, or additional copies of endogenous elements, or modified versions of native or endogenous genetic elements in order to alter at least one trait of a plant in a specific manner. Any sequences, such as DNA, whether from a different species or from the same species, which have been stably inserted into a genome using transformation are referred to herein collectively as “transgenes” and/or “transgenic events”. Transgenes can be moved from one genome to another using breeding techniques which may include crossing, backcrossing or double haploid production. In some embodiments, a transformed variant of PH2307GR may comprise at least one transgene or genetic modification but could contain at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 transgenes or genetic modifications and no more than 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, or 2 transgenes or genetic modifications. Transformed versions of the claimed variety PH2307GR as well as hybrid combinations containing and inheriting the transgene thereof are provided. F1 hybrid seed are provided which are produced by crossing a different plant with variety PH2307GR comprising a transgene introduced into variety PH2307GR by backcrossing or genetic transformation and is inherited by the F1 hybrid seed.
Numerous methods for plant transformation have been developed, including biological and physical plant transformation protocols. See, for example, Miki et al., “Procedures for Introducing Foreign DNA into Plants” in Methods in Plant Molecular Biology and Biotechnology, Glick, B.R. and Thompson, J.E. Eds. (CRC Press, Inc., Boca Raton, 1993) pages 67-88 and Armstrong, “The First Decade of Maize Transformation: A Review and Future Perspective” (Maydica 44:101-109, 1999) . In addition, expression vectors and in vitro culture methods for plant cell or tissue transformation and regeneration of plants are available. See, for example, Gruber et al., “Vectors for Plant Transformation” in Methods in Plant Molecular Biology and Biotechnology, Glick, B.R. and Thompson, J.E. Eds. (CRC Press, Inc., Boca Raton, 1993) pages 89-119.
In general, methods to transform, modify, edit or alter plant endogenous genomic DNA include altering the plant native DNA sequence or a pre-existing transgenic sequence including regulatory elements, coding and non-coding sequences. These methods can be used, for example, to target nucleic acids to pre-engineered target recognition sequences in the genome. Such pre-engineered target sequences may be introduced by genome editing or modification. As an example, a genetically modified plant variety is generated using “custom” or engineered endonucleases such as meganucleases produced to modify plant genomes (see e.g., WO 2009/114321; Gao et al. (2010) Plant Journal 1:176-187). Another site-directed engineering method is through the use of zinc finger domain recognition coupled with the restriction properties of restriction enzyme. See e.g., Urnov, et al., (2010) Nat Rev Genet. 11(9):636-46; Shukla, et al., (2009) Nature 459 (7245):437-41. A transcription activator-like (TAL) effector-DNA modifying enzyme (TALE or TALEN) is also used to engineer changes in plant genome. See e.g., US20110145940, Cermak et al., (2011) Nucleic Acids Res. 39(12) and Boch et al., (2009), Science 326(5959): 1509-12. Site-specific modification of plant genomes can also be performed using the bacterial type II CRISPR (clustered regularly interspaced short palindromic repeats)/Cas (CRISPR-associated) system. See e.g., Belhaj et al., (2013), Plant Methods 9: 39; The Cas9/guide RNA-based system allows targeted cleavage of genomic DNA guided by a customizable small noncoding RNA in plants (see e.g., WO 2015026883A1).
Plant transformation methods may involve the construction of an expression vector. Such a vector comprises a DNA sequence that contains a gene under the control of or operatively linked to a regulatory element, for example a promoter. The vector may contain one or more genes and one or more regulatory elements.
A transgenic event which has been engineered into a particular sorghum plant using transformation techniques, could be moved into another line using traditional breeding techniques that are well known in the plant breeding arts. For example, a backcrossing approach could be used to move a transgene from a transformed sorghum plant to an elite inbred line and the resulting progeny would comprise a transgene. Also, if an inbred line was used for the transformation then the transgenic plants could be crossed to a different line in order to produce a transgenic hybrid sorghum plant. As used herein, “crossing” can refer to a simple X by Y cross, or the process of backcrossing, depending on the context. Various genetic elements can be introduced into the plant genome using transformation. These elements include but are not limited to genes; coding sequences; inducible, constitutive, and tissue specific promoters; enhancing sequences; and signal and targeting sequences. For example, see, U.S. Pat. No. 6,118,055.
With transgenic plants according to the present discovery, a foreign protein can be produced in commercial quantities. Thus, techniques for the selection and propagation of transformed plants, which are well understood in the art, yield a plurality of transgenic plants which are harvested in a conventional manner, and a foreign protein then can be extracted from a tissue of interest or from total biomass. Protein extraction from plant biomass can be accomplished by known methods which are discussed, for example, by Heney and Orr, (1981) Anal. Biochem. 114:92-96.
A genetic map can be generated, primarily via conventional Restriction Fragment Length Polymorphisms (RFLP), Polymerase Chain Reaction (PCR) analysis, and Simple Sequence Repeats (SSR), and Single Nucleotide Polymorphisms (SNPs), which identifies the approximate chromosomal location of the integrated DNA molecule coding for the foreign protein. For exemplary methodologies in this regard, see, Glick and Thompson, METHODS IN PLANT MOLECULAR BIOLOGY AND BIOTECHNOLOGY 269-284 (CRC Press, Boca Raton, 1993). Map information concerning chromosomal location is useful for proprietary protection of a subject transgenic plant. If unauthorized propagation is undertaken and crosses made with other germplasm, the map of the integration region can be compared to similar maps for suspect plants, to determine if the latter have a common parentage with the subject plant. Map comparisons would involve hybridizations, RFLP, PCR, SSR, SNP, and sequencing, all of which are conventional techniques.
Likewise, by means of the present discovery, plants can be genetically engineered to express various phenotypes of agronomic interest. Exemplary transgenes implicated in this regard include, but are not limited to, those categorized below.
1. Genes that create a site for site specific DNA integration.
This includes the introduction of FRT sites that may be used in the FLP/FRT system and/or Lox sites that may be used in the Cre/Loxp system. For example, see, Lyznik, et al., (2003) “Site-Specific Recombination for Genetic Engineering in Plants”, Plant Cell Rep 21:925-932 and WO 99/25821, which are hereby incorporated by reference. Other systems that may be used include the Gin recombinase of phage Mu (Maeser, et aL, 1991), the Pin recombinase of E. coli (Enomoto, et aL, 1983), and the R/RS system of the pSR1 plasmid (Araki, et aL, 1992).
2. Genes that affect abiotic stress resistance (including but not limited to flowering, panicle/glume and seed development, enhancement of nitrogen utilization efficiency, altered nitrogen responsiveness, drought resistance or tolerance, cold resistance or tolerance, and salt resistance or tolerance) and increased yield under stress.
For example, see, WO 00/73475 where water use efficiency is altered through alteration of malate; U.S. Pat. Nos 5,892,009, 5,965,705, 5,929,305, 5,891,859, 6,417,428, 6,664,446, 6,706,866, 6,717,034, 6,801,104, WO2000060089, WO2001026459, WO2001035725, WO2001034726, WO2001035727, WO2001036444, WO2001036597, WO2001036598, WO2002015675, WO2002017430, WO2002077185, WO2002079403, WO2003013227, WO2003013228, WO2003014327, WO2004031349, WO2004076638, WO9809521 and WO9938977 describing genes, including CBF genes and transcription factors effective in mitigating the negative effects of freezing, high salinity, and drought on plants, as well as conferring other positive effects on plant phenotype; U.S. Patent Application Publication Number 2004/0148654 and WO01/36596 where abscisic acid is altered in plants resulting in improved plant phenotype such as increased yield and/or increased tolerance to abiotic stress; WO2000/006341, WO04/090143, U.S. patent application Ser. Nos 10/817,483 and 09/545,334 where cytokinin expression is modified resulting in plants with increased stress tolerance, such as drought tolerance, and/or increased yield. Also see WO0202776, WO03052063, JP2002281975, U.S. Pat. No. 6,084,153, WO0164898, U.S. Pat. No. 6,177,275 and U.S. Pat. No. 6,107,547 (enhancement of nitrogen utilization and altered nitrogen responsiveness). For ethylene alteration, see, U.S. Patent Application Publication Numbers 2004/0128719, 2003/0166197 and WO200032761. For plant transcription factors or transcriptional regulators of abiotic stress, see e.g., U.S. Patent Application Publication Number 2004/0098764 or U.S. Patent Application Publication Number 2004/0078852.
Other genes and transcription factors that affect plant growth and agronomic traits such as yield, flowering, plant growth and/or plant structure, can be introduced or introgressed into plants, see, e.g., WO97/49811 (LHY), WO98/56918 (ESD4), WO97/10339 and U.S. Pat. No. 6,573,430 (TFL), U.S. Pat. No. 6,713,663 (FT), WO96/14414 (CON), WO96/38560, WO01/21822 (VRN1), WO00/44918 (VRN2), WO99/49064 (GI), WO00/46358 (FRI), WO97/29123, U.S. Pat. Nos 6,794,560, 6,307,126 (GAI), WO99/09174 (D8 and Rht), and WO2004076638 and WO2004031349 (transcription factors).
3. Transgenes that confer or contribute to an altered grain characteristic, such as:
4. Genes that confer male sterility
There are several methods of conferring genetic male sterility available, such as multiple mutant genes at separate locations within the genome that confer male sterility, as disclosed in U.S. Pat. Nos. 4,654,465 and 4,727,219 to Brar, et al., and chromosomal translocations as described by Patterson in U.S. Pat. Nos. 3,861,709 and 3,710,511. In addition to these methods, Albertsen, et al., U.S. Pat. No. 5,432,068, describes a system of nuclear male sterility which includes: identifying a gene which is critical to male fertility; silencing this native gene which is critical to male fertility; removing the native promoter from the essential male fertility gene and replacing it with an inducible promoter; inserting this genetically engineered gene back into the plant; and thus creating a plant that is male sterile because the inducible promoter is not “on” resulting in the male fertility gene not being transcribed. Fertility is restored by inducing, or turning “on,” the promoter, which in turn allows the gene that confers male fertility to be transcribed.
For additional examples of nuclear male and female sterility systems and genes, see also, U.S. Pat. Nos. 5,859,341, 6,297,426, 5,478,369, 5,824,524, 5,850,014, and 6,265,640. See also, Hanson, Maureen R., et al., “Interactions of Mitochondrial and Nuclear Genes That Affect Male Gametophyte Development,” Plant Cell., 16:S154-S169 (2004), all of which are hereby incorporated by reference.
5. Transgenes That Confer Tolerance to A Herbicide, For Example:
Glyphosate tolerance is also imparted to plants that express a gene that encodes a glyphosate oxido-reductase enzyme as described more fully in U.S. Pat. Nos. 5,776,760 and 5,463,175. In addition glyphosate tolerance can be imparted to plants by the over expression of genes encoding glyphosate N-acetyltransferase. See, for example, US2004/0082770; US2005/0246798; and US2008/0234130. A DNA molecule encoding a mutant aroA gene can be obtained under ATCC accession No. 39256, and the nucleotide sequence of the mutant gene is disclosed in U.S. Pat. No. 4,769,061. European Patent Application No. 0 333 033 and U.S. Pat. No. 4,975,374 disclose nucleotide sequences of glutamine synthetase genes which confer tolerance to herbicides such as L-phosphinothricin. The nucleotide sequence of a phosphinothricin-acetyl-transferase gene is provided in European Patent Nos. 0 242 246 and 0 242 236. See also, U.S. Pat. Nos. 5,969,213; 5,489,520; 5,550,318; 5,874,265; 5,919,675; 5,561,236; 5,648,477; 5,646,024; 6,177,616 B1; and 5,879,903. Exemplary genes conferring resistance to phenoxy propionic acids, cyclohexanediones and cyclohexones, such as sethoxydim and haloxyfop, are the Acc1-S1, Acc1-S2 and Acc1-S3 genes described by Marshall et al., Theor. Appl. Genet. 83: 435 (1992).
6. Transgenes That Confer Resistance to Insects or Disease and That Encode, For Example:
Another embodiment of this invention is the method of harvesting the seed of the maize variety PH2307GR as seed for planting. Embodiments include cleaning the seed, treating the seed, and/or conditioning the seed. Cleaning the seed includes removing foreign debris such as weed seed and removing chaff, plant matter, from the seed. Conditioning the seed can include controlling the temperature and rate of dry down and storing seed in a controlled temperature environment. Seed treatment is the application of a composition to the seed such as a coating or powder. Methods for producing a treated seed include the step of applying a composition to the seed or seed surface. Some examples of compositions are insecticides, fungicides, pesticides, antimicrobials, germination inhibitors, germination promoters, cytokinins, and nutrients.
To protect and to enhance yield production and trait technologies, seed treatment options can provide additional crop plan flexibility and cost effective control against insects, weeds and diseases, thereby further enhancing the invention described herein. Seed material can be treated, typically surface treated, with a composition comprising combinations of chemical or biological herbicides, herbicide safeners, insecticides, fungicides, germination inhibitors and enhancers, nutrients, plant growth regulators and activators, bactericides, nematicides, avicides and/or molluscicides. These compounds are typically formulated together with further carriers, surfactants or application-promoting adjuvants customarily employed in the art of formulation. The coatings may be applied by impregnating propagation material with a liquid formulation or by coating with a combined wet or dry formulation.
Examples of the various types of compounds that may be used as seed treatments are provided in The Pesticide Manual: A World Compendium, C. D. S. Tomlin Ed., Published by the British Crop Production Council, which is hereby incorporated by reference. Some seed treatments that may be used on crop seed include, but are not limited to, one or more of abscisic acid, acibenzolar-S-methyl, avermectin, amitrol, azaconazole, azospirillum, azadirachtin, azoxystrobin, Bacillus spp. (including one or more of cereus, firmus, megaterium, pumilis, sphaericus, subtilis and/or thuringiensis), Bradyrhizobium spp. (including one or more of betae, canariense, elkanii, iriomotense, japonicum, liaonigense, pachyrhizi and/or yuanmingense), captan, carboxin, chitosan, clothianidin, copper, cyazypyr, difenoconazole, etidiazole, fipronil, fludioxonil, fluoxastrobin, fluquinconazole, flurazole, fluxofenim, harpin protein, imazalil, imidacloprid, ipconazole, isoflavenoids, lipo-chitooligosaccharide, mancozeb, manganese, maneb, mefenoxam, metalaxyl, metconazole, myclobutanil, PCNB, penflufen, penicillium, penthiopyrad, permethrine, picoxystrobin, prothioconazole, pyraclostrobin, rynaxypyr, S-metolachlor, saponin, sedaxane, TCMTB, tebuconazole, thiabendazole, thiamethoxam, thiocarb, thiram, tolclofos-methyl, triadimenol, trichoderma, trifloxystrobin, triticonazole and/or zinc. PCNB seed coat refers to EPA registration number 00293500419, containing quintozen and terrazole. TCMTB refers to 2-(thiocyanomethylthio) benzothiazole.
Seed varieties and seeds with specific transgenic traits may be tested to determine which seed treatment options and application rates may complement such varieties and transgenic traits in order to enhance yield. For example, a variety with good yield potential but head smut susceptibility may benefit from the use of a seed treatment that provides protection against head smut, a variety with good yield potential but cyst nematode susceptibility may benefit from the use of a seed treatment that provides protection against cyst nematode, and so on. Likewise, a variety encompassing a transgenic trait conferring insect resistance may benefit from the second mode of action conferred by the seed treatment, a variety encompassing a transgenic trait conferring herbicide resistance may benefit from a seed treatment with a safener that enhances the plants resistance to that herbicide, etc. Further, the good root establishment and early emergence that results from the proper use of a seed treatment may result in more efficient nitrogen use, a better ability to withstand drought and an overall increase in yield potential of a variety or varieties containing a certain trait when combined with a seed treatment.
Uses of Sorghum
Sorghum is used as livestock feed, as sugar or grain for human consumption, as biomass, and as raw material in industry. Sorghum grain can be used as livestock feed, such as to beef cattle, dairy cattle, hogs and poultry. In some embodiments, the plant is used as livestock feed in the form of fodder, silage, hay and pasture. In some embodiments, commodity plant products produced from hybrid seed such as food, feed, forage, and syrup are provided.
Provided are uses of sorghum in the form of bread, porridge, confectionaries and as an alcoholic beverage. Grain sorghum may be ground into flour and either used directly or blended with wheat or corn flour in the preparation of food products. In addition to direct consumption of the grain, sorghum has long been used in many areas of the world to make beer. The uses of sorghum, in addition to human consumption of kernels, include both products of dry and wet milling industries. The principal products of sorghum dry milling are grits, meal and flour. Starch and other extracts for food use can be provided by the wet milling process.
Also provided are uses of sorghum as an industrial raw material. Industrial uses include sorghum starch from the wet-milling industry and sorghum flour from the dry milling industry. Sorghum starch and flour have application in the paper and textile industries. Other industrial uses include applications in adhesives, building materials and as oil-well muds. Considerable amounts of sorghum, both grain and plant material, have been used in industrial alcohol production.
Characteristics of PH2307GR
Sorghum line PH2307GR has shown stability for traits listed in Table 1. It has been self-pollinated, bulk increased and checked for uniformity of plant type to assure genetic homozygosity and phenotypic stability. The line has been increased by hand pollination and in isolated field plantings with continued observation for uniformity. It has been observed to be uniform and stable for at least six generations.
Sorghum line PH2307GR has the characteristics shown in Table 1.
Provided are seed of sorghum line PH2307GR, plants of sorghum line PH2307GR, plant parts of sorghum line PH2307GR, and processes for making a plant that comprise crossing sorghum line PH2307GR with another plant. In some embodiments, PH2307GR may be provided with cytoplasm comprising a gene or genes that cause male sterility. Also disclosed are processes for making a plant containing in its genetic material one or more traits introgressed into PH2307GR through backcross conversion and/or transformation, and to the seed, plant and plant arts produced thereby. Hybrid sorghum seed, plant, or plant part produced by crossing the line PH2307GR or a locus conversion of PH2307GR with another plant are also provided.
The terms variants, modification and mutant refer to a hybrid or inbred seed or a plant produced by that hybrid or inbred seed which is phenotypically similar to PH2307GR.
The foregoing discovery has been described in detail by way of illustration and example for purposes of exemplification. However, it will be apparent that changes and modifications such as single gene modifications and mutations, somaclonal variants, variant individuals selected from populations of the plants of the instant variety, and the like, are considered to be within the scope of the present discovery. All references disclosed herein whether to journal, patents, published applications and the like are hereby incorporated in their entirety by reference.
Deposit
Applicant has made a deposit of at least 2500 seeds of Sorghum Variety PH2307GR with the American Type Culture Collection (ATCC), 10801 University Boulevard, Manassas, Va. 20110-2209, USA, with ATCC Deposit No. PTA-125072. The seeds deposited with the ATCC on Apr. 25, 2018 were obtained from the seed of the variety maintained by Pioneer Hi-Bred International, Inc., 7250 NW 62nd Avenue, Johnston, Iowa, 50131 since prior to the filing date of this application. Access to this seed will be available during the pendency of the application to the Commissioner of Patents and Trademarks and persons determined by the Commissioner to be entitled thereto upon request. Upon allowance of any claims in the application, the Applicant will make the deposit available to the public pursuant to 37 C.F.R. § 1.808. This deposit of the Sorghum Variety PH2307GR will be maintained in the ATCC depository, which is a public depository, for a period of 30 years, or 5 years after the most recent request, or for the enforceable life of the patent, whichever is longer, and will be replaced if it becomes nonviable during that period. Additionally, Applicant has or will satisfy all of the requirements of 37 C.F.R. § § 1.801—1.809, including providing an indication of the viability of the sample upon deposit. Applicant has no authority to waive any restrictions imposed by law on the transfer of biological material or its transportation in commerce. Applicant does not waive any infringement of rights granted under this patent or under the Plant Variety Protection Act (7 USC 2321 et seq.).
Sorghum line PH2307GR was developed from the F2 population of the single cross 2PJUYO6BGR x PHB337. Both 2PJUYO6BGR and PHB337 are proprietary lines of Pioneer Hi-Bred International Inc. Sorghum line PH2307GR can be used in breeding techniques to create hybrids and can be used as a female parent.
| Number | Name | Date | Kind |
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| 9549521 | Monk | Jan 2017 | B1 |
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| 2017, Science News EMBO. |
