Inbred corn line PHRE1

Abstract

According to the invention, there is provided an inbred corn line, designated PHRE1. This invention thus relates to the plants and seeds of inbred corn line PHRE1 and to methods for producing a corn plant produced by crossing the inbred line PHRE1 with itself or with another corn plant. This invention further relates to hybrid corn seeds and plants produced by crossing the inbred line PHRE1 with another corn line or plant.

Description

FIELD OF THE INVENTION

This invention is in the field of corn breeding, specifically relating to an inbred corn line designated PHRE1.

BACKGROUND OF THE INVENTION

Plant Breeding

Field crops are bred through techniques that take advantage of the plant's method of pollination. A plant is self-pollinated 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.

Corn plants (Zea mays L.) can be bred by both self-pollination and cross-pollination techniques. Corn has separate male and female flowers on the same plant, located on the tassel and the ear, respectively. Natural pollination occurs in corn when wind blows pollen from the tassels to the silks that protrude from the tops of the incipient ears.

The development of a hybrid corn variety involves three steps: (1) the selection of plants from various germplasm pools; (2) the selfing of the selected plants for several generation to produce a series of inbred lines, which, although different from each other, breed true and are highly uniform; and (3) crossing the selected inbred lines with unrelated inbred lines to produce the hybrid progeny (F.sub.1). During the inbreeding process in corn, the vigor of the lines decreases. Vigor is restored when two unrelated inbred lines are crossed to produce the hybrid progeny. 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 give a superior hybrid have been identified, the hybrid seed can be reproduced indefinitely as long as the homogeneity of the inbred parents is maintained.

The objective of commercial maize inbred line development programs is to develop new inbred lines that combine to produce high grain yields and superior agronomic performance in hybrid combination. The primary trait breeders seek is yield. However, other major agronomic traits are of importance in hybrid combination and have an impact on yield or otherwise provide superior performance in hybrid combinations. Such traits include percent grain moisture at harvest, relative maturity, resistance to stalk breakage, resistance to root lodging, grain quality, and disease and insect resistance. In addition the lines per se must have acceptable performance for parental traits such as seed yields, kernel sizes, pollen production, all of which affect ability to provide parental lines in sufficient quantity and quality for hybridization. Traits have been shown to be under genetic control and many if not all of the traits are affected by multiple genes. Thus, to be selected as an inbred line, the inbred must be able to combine such that the desired traits are passed to the hybrid and also be able to satisfy production requirements as a parental line.

Pedigree Breeding

The pedigree method of breeding is the mostly widely used methodology for new inbred line development.

In general terms this procedure consists of crossing two inbred lines to produce the non-segregating F.sub.1 generation, and self pollination of the F.sub.1 generation to produce the F.sub.2 generation that segregates for all factors for which the inbred parents differ. An example of this process is set forth below. Variations of this generalized pedigree method are used, but all these variations produce a segregating generation which contains a range of variation for the traits of interest.

EXAMPLE 1

Hypothetical Example of Pedigree Breeding Program

Consider a cross between two inbred lines that differ for alleles at five loci.

The parental genotypes are: ##STR1## the F.sub.1 from a cross between these two parents is: ##STR2## Selfing F.sub.1 will produce an F.sub.2 generation including the following genotypes: ##STR3##

The number of genotypes in the F.sub.2 is 3.sup.6 for six segregating loci (729) and will produce (2.sup.6)-2 possible new inbreds, (62 for six segregating loci).

Each inbred parent which is used in breeding crosses represents a unique combination of genes, and the combined effects of the genes define the performance of the inbred and its performance in hybrid combination. There is published evidence (Smith, O. S., J. S. C. Smith, S. L. Bowen, R. A. Tenborg and S. J. Wall, TAG 80: 833-840 (1990)) that each of these lines are different and can be uniquely identified on the basis of genetically-controlled molecular markers.

It has been shown (Hallauer, Arnel R. and Miranda, J. B. Fo. Quantitative Genetics in Maize Breeding, Iowa State University Press, Ames Iowa (1981)) that most traits of economic value in maize are under the genetic control of multiple genetic loci, and that there are a large number of unique combinations of these genes present in elite maize germplasm. If not, genetic progress using elite inbred lines would no longer be possible. Studies by Duvick and Russell (Duvick, D. N. Maydica 37: 69-79 (1992); Russell, W. A. Maydica XXIX:375-390 (1983)) have shown that over the last 50 years the rate of genetic progress in commercial hybrids has been between 1 and 2% per year.

The number of genes affecting the trait of primary economic importance in maize, grain yield, has been estimated to be in the range of 10-1000. Inbred lines which are used as parents for breeding crosses differ in the number and combination of these genes. These factors make the plant breeder's task more difficult. Compounding this is evidence that no one line contains the favorable allele at all loci, and that different alleles have different economic values depending on the genetic background and field environment in which the hybrid is grown. Fifty years of breeding experience shows that there are many genes affecting grain yield and each of these has a relatively small effect on this trait. The effects are small compared to breeders' ability to measure grain yield differences in evaluation trails. Therefore, the parents of the breeding cross must differ at several of these loci so that the genetic differences in the progeny will be large enough that breeders can develop a line that increases the economic worth of its hybrids over that of hybrids made with either parent.

If the number of loci segregating in a cross between two inbred lines is n, the number of unique genotypes in the F.sub.2 generation is 3.sup.n (Table 2) and the number of unique inbred lines from this cross is {(2.sup.n) -2}. Only a very limited number of these combinations are useful. Only about 1 in 10,000 of the progeny from F.sub.2 's are commercially useful

By way of example, if it is assumed that the number of segregating loci in F.sub.2 is somewhere between 20 and 50, and that each parent is fixed for half the favorable alleles, it is then possible to calculate approximate probabilities of finding an inbred that has the favorable allele at {(n/2)+m} loci, where n/2 is the number of favorable alleles in each of the parents and m is the number of additional favorable alleles in the new inbred. See Example 2 below. The number m is assumed to be greater than three because each allele has so small an effect that evaluation techniques are not sensitive enough to detect differences due to three or less favorable alleles. The probabilities in Example 2 are on the order of 10.sup.-5 or smaller and they are the probabilities that at least one genotype with (n/2)+m favorable alleles will exist.

To put this in perspective the number of plants grown on 60 million acres (approximate US corn acreage) at 25000 plants/acre is 1.5.times.10.sup.12.

EXAMPLE 2

Probability of Finding an Inbreed with m of n Favorable Alleles

Assume each parent has n/2 of the favorable alleles and only 1/2 of the combinations of loci are economically useful.

______________________________________no. of no. favorable no. additional Probabilitysegregating alleles in favorable alleles that genotypeloci (n) Parents (n/2) in new inbred occurs*______________________________________20 10 14 3 .times. 10.sup.-524 12 16 2 .times. 10.sup.-528 14 18 1 .times. 10.sup.-532 16 20 8 .times. 10.sup.-636 18 22 5 .times. 10.sup.-640 20 24 3 .times. 10.sup.-644 22 26 2 .times. 10.sup.-648 24 28 1 .times. 10.sup.-6______________________________________ *Probability that a useful combination exists, does not include the probability of identifying this combination if it does exist.

The possibility of having a usably high probability of actually being able to identify this genotype based on replicated field testing would be most likely smaller than this, and is a function of how large a population of genotypes is tested and how testing resources are allocated in the testing program.

At Pioneer Hi-Bred International, a typical corn research station has a staff of four, and 20 acres of breeding nursery. Those researchers plant those 20 acres with 25,000 nursery rows, 15,000 yield test plots in 10-15 yield test sites, and one or two disease-screening nurseries. Employing a temporary crew of 20 to 30 pollinators, the station makes about 65,000 hand pollinations per growing season. Thus, one of the largest plant breeding programs in the world does not have a sufficiently large breeding population to be able to rely upon "playing the numbers" to obtain successful research results. Nevertheless, Pioneer's breeders at each station produce from three to ten new inbreds which are proposed for commercial use each year. Over the 32 Pioneer research stations in North America, this amounts to from about 100 to 300 new inbreds proposed for use, and less than 50 and more commonly less than 30 of these inbreds that actually satisfy the performance criteria for commercial use.

This is a result of plant breeders using their skills, experience, and intuitive ability to select inbreds having the necessary qualities.

SUMMARY OF THE INVENTION

According to the invention, there is provided a novel inbred corn line, designated PHRE1. This invention thus relates to the seeds of inbred corn line PHRE1, to the plants of inbred corn line PHRE1, and to methods for producing a corn plant produced by crossing the inbred line PHRE1 with itself or another corn line. This invention further relates to hybrid corn seeds and plants produced by crossing the inbred line PHRE1 with another corn line.

DEFINITIONS

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. ABS is in absolute terms and % MN is percent of the mean for the experiments in which the inbred or hybrid was grown.

BAR PLT=BARREN PLANTS. The percent of plants per plot that were not barren (lack ears).

BRT STK=BRITTLE STALKS. This is a measure of the stalk breakage near the time of pollination, and is an indication of whether a hybrid or inbred would snap or break near the time of flowering under severe winds. Data are presented as percentage of plants that did not snap.

BU ACR=YIELD (BUSHELS/ACRE). Actual yield of the grain at harvest in bushels per acre adjusted to 15.5% moisture.

DRP EAR=DROPPED EARS. A measure of the number of dropped ears per plot and represents the percentage of plants that did not drop ears prior to harvest.

EAR HT=EAR HEIGHT. The ear height is a measure from the ground to the highest placed developed ear node attachment and is measured in inches.

EAR SZ=EAR SIZE. A 1 to 9 visual rating of ear size. The higher the rating the larger the ear size.

EST CNT=EARLY STAND COUNT. This is a measure of the stand establishment in the spring and represents the number of plants that emerge on a per plot basis for the inbred or hybrid.

GDU SHD=GDU TO SHED. The number of growing degree units (GDUs) or heat units required for an inbred line or hybrid to have approximately 50 percent of the plants shedding pollen and is measured from the time of planting. Growing degree units are calculated by the Barger Method, where the heat units for a 24-hour period are: ##EQU1##

The highest maximum temperature used is 86.degree. F. and the lowest minimum temperature used is 50.degree. F. For each inbred or hybrid it takes a certain number of GDUs to reach various stages of plant development.

GDU SLK=GDU TO SILK. The number of growing degree units required for an inbred line or hybrid to have approximately 50 percent of the plants with silk emergence from time of planting. Growing degree units are calculated by the Barger Method as given in GDU SHD definition.

GRN APP=GRAIN APPEARANCE. This is a 1 to 9 rating for the general appearance of the shelled grain as it is harvested based on such factors as the color of the harvested grain, any mold on the grain, and any cracked grain. High scores indicate good grain quality.

MST=HARVEST MOISTURE. The moisture is the actual percentage moisture of the grain at harvest.

PLT HT=PLANT HEIGHT. This is a measure of the height of the plant from the ground to the tip of the tassel in inches.

POL SC=POLLEN SCORE. A 1 to 9 visual rating indicating the amount of pollen shed. The higher the score the more pollen shed.

POL WT=POLLEN WEIGHT. This is calculated by dry weight of tassels collected as shedding commences minus dry weight from similar tassels harvested after shedding is complete.

It should be understood that the inbred can, through routine manipulation of cytoplasmic factors, be produced in a cytoplasmic male-sterile form which is otherwise phenotypically identical to the male-fertile form.

PRM=PREDICTED RM. This trait, predicted relative maturity (RM), is based on the harvest moisture of the grain. The relative maturity rating is based on a known set of checks and utilizes standard linear regression analyses and is referred to as the Comparative Relative Maturity Rating System which is similar to the Minnesota Relative Maturity Rating System.

RT LDG=ROOT LODGING. Root lodging is the percentage of plants that do not root lodge; plants that lean from the vertical axis at an approximately 30.degree. angle or greater would be counted as root lodged.

SCT GRN=SCATTER GRAIN. A 1 to 9 visual rating indicating the amount of scatter grain (lack of pollination or kernel abortion) on the ear. The higher the score the less scatter grain.

SDG VGR=SEEDLING VIGOR. This is the visual rating (1 to 9) of the amount of vegetative growth after emergence at the seedling stage (approximately five leaves). A higher score indicates better vigor.

SEL IND=SELECTION INDEX. The selection index gives a single measure of the hybrid's worth based on information for up to five traits. A corn breeder may utilize his or her own set of traits for the selection index. One of the traits that is almost always included is yield. The selection index data presented in the tables represent the mean value averaged across testing stations.

STA GRN=STAY GREEN. Stay green is the measure of plant health near the time of black layer formation (physiological maturity). A high score indicates better late-season plant health.

STK CNT=NUMBER OF PLANTS. This is the final stand or number of plants per plot.

STK LDG=STALK LODGING. This is the percentage of plants that did not stalk lodge (stalk breakage) as measured by either natural lodging or pushing the stalks and determining the percentage of plants that break below the ear.

TAS BLS=TASSEL BLAST. A 1 to 9 visual rating was used to measure the degree of blasting (necrosis due to heat stress) of the tassel at time of flowering. A 1 would indicate a very high level of blasting at time of flowering, while a 9 would have no tassel blasting.

TAS SZ=TASSEL SIZE. A 1 to 9 visual rating was used to indicate the relative size of the tassel. The higher the rating the larger the tassel.

TAS WT=TASSEL WEIGHT. This is the average weight of a tassel (grams) just prior to pollen shed.

TEX EAR=EAR TEXTURE. A 1 to 9 visual rating was used to indicate the relative hardness (smoothness of crown) of mature grain. A 1 would be very soft (extreme dent) while a 9 would be very hard (flinty or very smooth crown).

TILLER=TILLERS. A count of the number of tillers per plot that could possibly shed pollen was taken. Data is given as percentage of tillers: number of tillers per plot divided by number of plants per plot.

TST WT=TEST WEIGHT (UNADJUSTED). The measure of the weight of the grain in pounds for a given volume (bushel).

TST WTA=TEST WEIGHT ADJUSTED. The measure of the weight of the grain in pounds for a given volume (bushel) adjusted for percent moisture.

YLD=YIELD. It is the same as BU ACR ABS.

YLD SC=YIELD SCORE. A 1 to 9 visual rating was used to give a relative rating for yield based on plot ear piles. The higher the rating the greater visual yield appearance.

MDM CPX=Maize Dwarf Mosaic Complex (MDMV=Maize Dwarf Mosaic Virus & MCDV=Maize Chlorotic Dwarf Virus): Visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant.

SLF BLT=Southern Leaf Blight (Bipolaris maydis, Helminthosporium maydis): Visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant.

NLF BLT=Northern Leaf Blight (Exserohilum turcicum, H. turcicum): Visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant.

COM RST=Common Rust (Puccinia sorghi): Visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant.

GLF SPT=Gray Leaf Spot (Cercospora zeae-maydis): Visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant.

STW WLT=Stewart's Wilt (Erwinia stewartii): Visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant.

HD SMT=Head Smut (Sphacelotheca reiliana): Percentage of plants that did not have infection.

EAR MLD=General Ear Mold: Visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant. This is based on overall rating for ear mold of mature ears without determining specific mold organism, and may not be predictive for a specific ear mold.

ECB DPE=Dropped ears due to European Corn Borer (Ostrinia nubilalis): Percentage of plants that did not drop ears under second brood corn borer infestation.

ECB 2SC=European Corn Borer Second Brood (Ostrinia nubilalis): Visual rating (1-9 score) of post flowering damage due to infestation by European Corn Borer. A "1" is very susceptible and a "9" is very resistant.

ECB 1LF=European Corn Borer First Brood (Ostrinia nubilalis): Visual rating (1-9 score) of pre-flowering leaf feeding by European Corn Borer. A "1" is very susceptible and a "9" is very resistant.

DETAILED DESCRIPTION OF THE INVENTION

PHRE1 was selected and kept because of its ability to cross with other inbreds and produce single-cross hybrids which exhibited significant yield advantage. PHRE1 has the ability to cross with elite inbreds, of later maturities, to produce superior performing hybrids in later maturity zones. The ability of an early inbred (PHRE1) to cross with later inbreds to produce hybrids of later maturity, which show a yield advantage in later maturities is unique and can only be found by extensive research. This is to say, to have an early inbred which can contribute favorable alleles for single cross yield corn in later maturities is unique and valuable. This is opposed to a narrow band of maturities, as we attempt to exploit the favorable alleles found in PHRE1. It allows for more opportunity to cross and evaluate hybrids with significant yield performance over a wide range of maturity. It also allows for more opportunity in developing breeding crosses which give rise to the next generation of superior parents.

Inbred corn line PHRE1 is a yellow, dent corn inbred that provides an acceptable female parental line in crosses for producing first generation F1 corn hybrids. PHRE1 is adapted to most regions of the United States. PHRE1 hybrids exhibit high yield potential, generally good agronomic traits, and respond very well to high yield environments. PHRE1 has a wide area of adaptation. It appears to have the ability to cross with inbreds of later maturity and offers high yield potential in later maturities, something which has not previously occurred. PHRE1 is unique genetically and offers the opportunity for the plant breeder to create distinctly unique hybrids which are profitable to produce, and profitable for the farmer to grow.

The inbred has shown uniformity and stability within the limits of environmental influence for all the traits as described in the Variety Description Information (Table 1) that follows. Most of the data in the Variety Description information was collected at Johnston, Iowa. The inbred has been self-pollinated and ear-rowed a sufficient number of generations with careful attention paid to uniformity of plant type to ensure homozygosity and phenotypic stability. The line has been increased both by hand and in isolated fields with continued observation for uniformity. No variant traits have been observed or are expected in PHRE1.

Inbred corn line PHRE1, being substantially homozygous, can be reproduced by planting seeds of the line, growing the resulting corn plants under self-pollinating or sib-pollinating conditions with adequate isolation, and harvesting the resulting seed, using techniques familiar to the agricultural arts.

TABLE 1______________________________________VARIETY DESCRIPTION INFORMATIONINBRED = PHRE1Type: Dent Region Best Adapted: MOST REGIONS______________________________________A. Maturity: Average across maturity zones. Zone: 0 Heat Unit Shed: 1250 Heat Unit Silk: 1250 No. Reps: 39 ##STR4## *If maximum is greater than 86 degrees fahrenheit, then 86 is used and if minimum is less than 50, then 50 is used. Heat units accumulated daily an can not be less than 0. B. Plant Characteristics: Plant height (to tassel tip): 160 cm Length of top ear internode: 12 cm Number of ears per stalk: SINGLE Ear height 64 cm (to base of top ear): Number of tillers: NONE Cytoplasm type: NORMALC. Leaf Color: (B14) DARK GREEN Angle from Stalk: 30-60 degrees Marginal Waves: (WF9) FEW Number of Leaves 17 (mature plants): Sheath Pubescence: (W22) LIGHT Longitudinal Creases: (OH56A) FEW Length (Ear node leaf): 61 cm Width (widest point, 9 cm ear node leaf):D. Tassel: Number lateral branches: 4 Branch Angle from >45 degrees central spike: Pollen Shed: Light based on Pollen Yield Test (77% of experiment means) Peduncle Length 14 cm (top leaf to basal branches): Anther Color: YELLOW Glume Color: GREENE. Ear (Husked Ear Data Except When Stated Otherwise): Length: 14 cm Weight: 103 gm Mid-point Diameter: 38 mm Silk Color: YELLOW Husk Extension MEDIUM (Harvest stage): (Barely Covering Ear) Husk Leaf: SHORT (<8 cm) Taper of Ear: SLIGHT Position of Shank UPRIGHT (dry husks): Kernel Rows: STRAIGHT DISTINCT Number = 14 Husk Color (fresh): LIGHT GREEN Husk Color (dry): BUFF Shank Length: 8 cm Shank (No. of internodes): 7F. Kernel (Dried): Size (from ear mid-point) Length: 10 mm Width: 8 mm Thick: 5 mm Shape Grade (% rounds): 20-40 (27% medium round based on Parent Test Data) Pericarp Color: COLORLESS Aleurone Color: HOMOZYGOUS YELLOW Endosperm Color: YELLOW Endosperm Type: NORMAL STARCH Gm Wt/100 Seeds (unsized): 26 gmG. Cob: Diameter at mid-point: 23 mm Strength: WEAK Color: REDH. Diseases: N. Leaf Blight (E. turcicum): INTERMEDIATE Common Rust (P. sorghi): HIGHLY RESISTANT Goss's Wilt (C. nebraskense): RESISTANT Common Smut (U. maydis): HIGHLY RESISTANT Head Smut (S. reiliana): HIGHLY RESISTANT Fusarium Ear Mold RESISTANT (F. moniliforme):I. Insects: European Corn Borer-1 SUSCEPTIBLE Leaf Damage (Pre-flowering): European Corn Borer-2 SUSCEPTIBLE (Post-flowering): The above descriptions are based on a scale of 1-9, 1 being highly susceptible, 9 being highly resistant. S (Susceptible): Would generally represent a score of 1-3. I (Intermediate): Would generally represent a score of 4-5. R (Resistant): Would generally represent a score of 6-7. H (Highly Resistant): Would generally represent a score of 8-9. Highly resistant does not imply the inbred is immune.J. Variety Most Closely Resembling: Character Inbred Maturity PHJ40 Usage PHJ40 PHJ40 (PVP Certificate No. 8600133) is a Pioneer HiBred International, Inc. proprietary inbred. Data for Items B, C, D, E, F, and G is based primarily on a maximum of 4 reps from Johnston, Iowa grown in 1991 and 1992, plus description information from the maintaining station.

ELECTROPHORESIS RESULTS

Isozyme Genotypes for PHRE1

Isozyme data were generated for inbred corn line PHRE1 according to the procedures described in Stuber, C. W., Wendel, J. F., Goodman, M. M., and Smith, J. S. C., "Techniques and Scoring Procedures for Starch Gel Electrophoresis of Enzymes from Maize (Zea mays L.)", Technical Bulletin No. 286, North Carolina Agricultural Research Service, North Carolina State University, Raleigh, N.C. (1988).

The data in Table 2 compares PHRE1 with its parents, PHJ40 and PHR47.

TABLE 2______________________________________ELECTROPHORESIS RESULTS FOR PHRE1AND ITS PARENTS PHJ40 AND PHR47 PARENTSLOCI PHRE1 PHJ40 PHR47______________________________________ACP1 4 2 4ADH1 4 4 6CAT3 9 9 9DIA1 8 8 8GOT1 4 4 4GOT2 4 4 4GOT3 4 4 4IDH1 4 4 4IDH2 6 6 6MDH1 6 6 6MDH2 6 6 6MDH3 16 16 16MDH4 12 12 12MDH5 12 12 12MMM 4 4 8PGM1 9 9 9PGM2 4 4 4PGD1 3.8 3.8 3.8PGD2 5 5 5PHI1 4 4 4______________________________________

EXAMPLE 3

Inbred and Hybrid Performance of PHRE1

In the examples that follow, the traits and characteristics of inbred corn line PHRE1 are given as a line in comparison with other inbreds and in hybrid combination. The data collected on inbred line PHRE1 is presented for the key characteristics and traits.

The results in Table 3A compare PHRE1 to its PHJ40 parent. PHRE1 has slightly higher yield and significantly higher grain harvest moisture. PHRE1 is a shorter inbred with lower ear placement and flowers similarly to PHJ40. PHRE1 has better resistance to ear mold, northern leaf blight, and first brood European corn borer than PHJ40.

Table 3B compares PHRE1 to its PHR47 parent. PHRE1 and PHR47 have similar yield, however, PHRE1 has lower grain moisture at harvest and higher test weight. PHRE1 is a significantly shorter inbred with lower ear placement and flowers (GDU Shed and GDU Silk) significantly earlier than PHR47.

The results in Table 3C show PHRE1 has significantly higher yield and test weight than PHN37. PHRE1 is shorter with lower ear placement and flowers (GDU Shed and GDU Silk) earlier than PHN37. PHRE1 has better ear texture and fewer scatter grain than PHN37.

Table 4 compares PHRE1 to PHJ40 when both are crossed to the same inbred testers. The results show the PHRE1 hybrids have higher yield and lower grain harvest moisture than the PHJ40 hybrids. The hybrids are similar in height, but the PHRE1 hybrids have higher ear placement.

Table 5A compares PHRE1 to PHR47 when both are crossed to the same inbred. The hybrids have similar yield, but the PHRE1 hybrid has significantly lower grain harvest moisture. The PHRE1 hybrid has poorer staygreen, but better grain appearance compared to the PHR47 hybrid. The PHRE1 hybrid is shorter with lower ear placement and sheds (GDU Shed) earlier than the PHR47 hybrid.

Table 5B compares PHRE1 to PHJ40 when both are crossed to the same inbred. The PHRE1 hybrid and the PHR40 hybrid have similar yield and grain harvest moisture, but the PHRE1 hybrid has lower test weight. The hybrids have similar stalk lodging resistance, but the PHRE1 hybrid has better root lodging resistance. The PHRE1 hybrid and the PHJ40 hybrid are similar in height, but the PHRE1 hybrid has lower ear placement.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 compares the yield of PHRE1 and PHJ40. PHRE1 is a higher yielding inbred across environments than PHJ40. Both inbreds have slightly above average yield in low yielding environments, but are below average yielding in high yield environments.

TABLE 3A__________________________________________________________________________PAIRED INBRED COMPARISON DATAVARIETY #1 - PHRE1VARIETY #2 - PHJ40 BU BU YLD EAR BAR PLT EAR SDG EST VAR ACR ACR SC MST SZ PLT HT HT VGR CNTDEPT # ABS % MN ABS ABS ABS ABS ABS ABS ABS ABS__________________________________________________________________________TOTAL 1 70.4 101 6.3 18.8 5.4 92.2 63.6 26.1 5.9 40.7SUM 2 67.2 95 6.3 17.8 5.3 92.3 65.5 28.3 5.3 40.1 LOCS 30 30 14 35 8 34 41 41 38 84 REPS 96 96 15 96 8 47 77 79 60 185 DIFF 3.2 5 0.0 0.9 0.1 0.0 1.9 2.2 0.6 0.6 PROB .111 .073* .000# .001# .685 .978 .007# .000# .019+ .301__________________________________________________________________________ DRP TIL GDU GDU POL POL POL TAS TAS TEX VAR EAR LER SHD SLK WT WT SC BLS SZ EAR DEPT # ABS ABS ABS ABS ABS % MN ABS ABS ABS ABS__________________________________________________________________________ TOTAL 1 99.9 1.3 1185 1183 100.1 79 5.3 9.0 4.5 5.4 SUM 2 99.7 1.9 1181 1195 109.0 87 4.9 8.8 4.6 6.9 LOCS 18 44 61 50 9 9 27 5 19 7 REPS 42 83 92 64 17 17 40 9 20 7 DIFF 0.2 0.6 04 12 8.9 8 0.4 0.2 0.1 1.4 PROB .205 .268 2.59 .013+ .421 .353 .059* .374 .772 .008#__________________________________________________________________________ TST GRN SCT STA STK RT EAR NLF ECB ECB VAR WT APP GRN GRN LDG LDG MLD BLT 1LF 2SC DEPT # ABS ABS ABS ABS ABS ABS ABS ABS ABS ABS__________________________________________________________________________ TOTAL 1 58.9 6.2 8.1 4.1 94.3 91.1 7.8 4.9 4.0 3.3 SUM 2 58.6 6.0 7.8 4.0 96.7 97.6 7.2 4.1 3.2 4.0 LOCS 30 17 14 13 20 8 12 7 16 8 REPS 93 35 15 25 50 17 13 7 16 12 DIFF 0.3 0.2 0.3 0.1 2.4 6.4 0.7 0.7 0.8 0.8 PROB .215 .300 .302 .712 .030+ .127 .054* .094* .043+ .149__________________________________________________________________________ * = 10% SIG + = 5% SIG # = 1% SIG TABLE 3B__________________________________________________________________________PAIRED INBRED COMPARISON DATAVARIETY #1 = PHRE1VARIETY #2 = PHR47 BU BU YLD EAR BAR PLT EAR SDG EST VAR ACR ACR SC MST SZ PLT HT HT VGR CNTDEPT # ABS % MN ABS ABS ABS ABS ABS ABS ABS ABS__________________________________________________________________________TOTAL 1 77.7 111 5.0 14.6 4.8 86.7 62.1 25.1 6.0 26.5SUM 2 78.3 113 5.6 18.7 6.0 87.5 84.8 34.7 4.8 26.5 LOCS 3 3 8 4 4 15 13 13 20 36 REPS 6 6 9 7 4 18 17 17 23 82 DIFF 0.6 2 0.6 4.1 1.3 0.8 22.7 9.5 1.2 0.1 PROB .964 .921 .370 .133 .194 .847 .000# .000# .005# .910__________________________________________________________________________ TIL GDU GDU POL TAS TAS TEX TST VAR LER SHD SLK SC BLS SZ EAR WTDEPT # ABS ABS ABS ABS ABS ABS ABS ABS__________________________________________________________________________TOTAL 1 1.7 1190 1198 4.3 9.0 4.7 5.0 62.0SUM 2 1.4 1379 1412 5.7 9.0 5.7 5.5 57.5 LOCS 16 28 26 7 1 10 4 3 REPS 20 31 28 8 1 11 4 6 DIFF 0.3 189 214 1.4 0.0 1.0 0.5 4.5 PROB .771 .000# .000# .008# .032+ .604 .051*__________________________________________________________________________ GRN SCT STA STK RT EAR NLF ECB ECB VAR APP GRN GRN LDG LDG MLD BLT 1LF 2SC DEPT # ABS ABS ABS ABS ABS ABS ABS ABS ABS__________________________________________________________________________ TOTAL 1 5.0 6.6 2.2 94.7 95.2 6.8 4.2 4.1 3.0 SUM 2 5.0 5.6 6.1 96.2 89.5 7.2 5.4 4.5 6.0 LOCS 1 7 5 3 1 6 5 12 4 REPS 1 8 8 6 1 7 5 12 4 DIFF 0.0 1.0 3.9 1.5 5.8 0.3 1.2 0.4 3.0 PROB .442 .000# .789 .721 .324 .376 .000#__________________________________________________________________________ * = 10% SIG + = 5% SIG # = 1% SIG TABLE 3C__________________________________________________________________________PAIRED INBRED COMPARISON DATAVARIETY #1 - PHRE1VARIETY #2 - PHN37 BU BU YLD EAR BAR PLT EAR SDG EST VAR ACR ACR SC MST SZ PLT HT HT VGR CNTDEPT # ABS % MN ABS ABS ABS ABS ABS ABS ABS ABS__________________________________________________________________________TOTAL 1 77.7 111 5.7 15.7 5.0 97.7 63.0 24.5 6.4 36.3SUM 2 44.1 63 4.1 14.4 4.6 94.3 73.6 22.6 5.6 35.7 LOCS 3 3 7 3 5 6 14 14 16 25 REPS 6 6 7 6 5 9 17 17 19 32 DIFF 33.6 49 1.6 1.3 0.4 3.3 10.6 1.8 0.8 0.6 PROB .015+ .019+ .081* .123 .477 .418 .000# .077* .098* .595__________________________________________________________________________ TIL GDU GDU POL POL POL TAS TAS TEX VAR LER SHD SLK WT WT SC BLS SZ EAR DEPT # ABS ABS ABS ABS % MN ABS ABS ABS ABS__________________________________________________________________________ TOTAL 1 1.0 1202 1202 113.7 84 5.7 9.0 5.1 5.0 SUM 2 0.6 1227 1267 107.9 80 5.8 9.0 4.9 3.3 LOCS 16 25 23 2 2 9 1 7 6 REPS 22 31 28 4 4 13 2 7 6 DIFF 0.5 25 65 5.8 4 0.2 0.0 0.3 1.7 PROB .315 .051* .000# .690 .722 .710 .522 .020+__________________________________________________________________________ TST GRN SCT STA STK RT EAR NLF ECB ECB VAR WT APP GRN GRN LDG LDG MLD BLT 1LF 2SC DEPT # ABS ABS ABS ABS ABS ABS ABS ABS ABS ABS__________________________________________________________________________ TOTAL 1 62.0 5.0 8.2 1.7 94.7 95.2 7.8 1.0 3.2 2.0 SUM 2 55.7 5.0 5.8 1.3 96.8 95.4 6.2 1.0 2.5 4.0 LOCS 3 1 6 3 3 1 5 1 6 1 REPS 6 1 6 6 6 1 5 1 6 1 DIFF 6.3 0.0 2.3 0.3 2.1 0.2 1.6 0.0 0.7 2.0 PROB .010+ .017+ .184 .689 .294 .394__________________________________________________________________________ * = 10% SIG + = 5% SIG # = 1% SIG TABLE 4__________________________________________________________________________AVERAGE INBRED BY TESTER PERFORMANCE COMPARING PHRE1 TO PHJ40CROSSED TO THE SAME INBRED TESTERS AND GROWN IN THE SAME EXPERIMENTS.ALL VALUES ARE EXPRESSED AS PERCENT OF THE EXPERIMENT MEAN EXCEPTPREDICTED RM, SELECTION INDEX, AND YIELD (BU/ACR). BU GDU PRM STK TST EST STK PLT EAR DRP PRM ACR YLD MST SHD SHD LDG WTA CNT CNT HT HT EAR__________________________________________________________________________TOTAL REPLIC. 3 3 3 3 1 2 2 3 1 4 2 2 1MEAN WTS PHRE1 89 127 115 89 101 91 106 98 99 101 103 113 100MEAN WTS PHJ40 92 119 108 96 102 93 114 99 101 97 104 108 100 DIFF. 3 8 7 7 1 1 7 1 1 3 0 5__________________________________________________________________________ TABLE 5A__________________________________________________________________________VARIETY #1 = PHRE1 HYBRIDVARIETY #2 = PHR47 HYBRID BU BU STK RT STA TST GRN SDG VAR PRM ACR ACR MST LDG LDG GRN WTA APP VGRDEPT # PRM SHD ABS % MN % MN % MN % MN % MN % MN % MN %__________________________________________________________________________ MNTOTAL 1 98 97 161.7 104 94 101 102 79 99 99 104SUM 2 105 102 164.4 106 111 102 106 121 98 86 100 LOCS 12 6 37 37 38 37 17 12 36 18 15 REPS 12 7 44 44 45 44 23 12 43 21 16 DIFF 7 5 2.6 1 18 1 4 43 0 13 4 PROB .000# .000# .432 .514 .000# .206 .461 .011+ .329 .011+ .541__________________________________________________________________________ EST STK PLT EAR DRP BRT GDU VAR CNT CNT HT HT EAR STK SHD DEPT # % MN % MN % MN % MN % MN % MN %__________________________________________________________________________ MN TOTAL 1 102 101 95 99 100 99 97 SUM 2 98 99 106 105 100 101 102 LOCS 20 45 16 16 18 2 12 REPS 22 57 17 17 22 2 12 DIFF 4 3 11 6 0 2 4 PROB .010+ .008# .000# .022+ .459 .500 .000#__________________________________________________________________________ * = 10% SIG + = 5% # = 1% SIG TABLE 5B__________________________________________________________________________VARIETY #1 = PHRE1 HYBRIDVARIETY #2 = PHJ40 HYBRID BU BU STK RT STA TST VAR PRM ACR ACR MST LDG LDG GRN WTADEPT # PRM SHD ABS % MN % MN % MN % MN % MN % MN__________________________________________________________________________TOTAL 1 86 86 121.6 104 94 105 91 89 98SUM 2 87 86 120.2 103 95 104 84 88 100 LOCS 25 19 76 76 79 72 6 13 79 REPS 25 19 142 142 148 139 14 23 148 DIFF 0 0 1.5 1 2 1 8 1 2 PROB .245 .378 .290 .269 .103 .117 .097* .902 .000#__________________________________________________________________________ GRN SDG EST STK PLT EAR DRP BRT GDU VAR APP VGR CNT CNT HT HT EAR STK SHDDEPT # % MN % MN % MN % MN % MN % MN % MN % MN % MN__________________________________________________________________________TOTAL 1 91 94 97 100 97 98 100 100 99SUM 2 89 93 97 100 98 100 100 100 99 LOCS 61 61 65 81 53 53 50 3 35 REPS 119 113 132 153 99 99 96 6 69 DIFF 2 1 0 0 1 2 0 0 0 PROB .416 .687 .701 .811 .136 .067* .363 .700 .125__________________________________________________________________________ * = 10% SIG + = 5% SIG # = 1% SIG

INDUSTRIAL APPLICABILITY

The foregoing is set forth by way of example and is not intended to limit the scope of the invention.

This invention also is directed to methods for producing a corn plant by crossing a first parent corn plant with a second parent corn plant wherein the first or second parent corn plant is an inbred corn plant from the line PHRE1. Further, both first and second parent corn plants can come from the inbred corn line PHRE1. Thus, any such methods using the inbred corn line PHRE1 are part of this invention: selfing, backcrosses, hybrid production, crosses to populations, and the like. It also would include more unconventional methods of combining the inbred with another such as using various culturing techniques known to those skilled in the art. All plants produced using inbred corn line PHRE1 as a parent are within the scope of this invention. Advantageously, the inbred corn line is used in crosses with other, different, corn inbreds to produce first generation (F.sub.1) corn hybrid seeds and plants with superior characteristics.

As used herein, the term plant includes plant cells, plant protoplasts, plant cell tissue cultures from which corn plants can be regenerated, plant calli, plant clumps, and plant cells that are intact in plants or parts of plants, such as embryos, pollen, flowers, kernels, ears, cobs, leaves, husks, stalks, roots, root tips, anthers, silk and the like.

Duncan, Williams, Zehr, and Widholm, Planta, (1985) 165: 322-332 reflects that 97% of the plants cultured which produced callus were capable of plant regeneration. Subsequent experiments with both inbreds and hybrids produced 91% regenerable callus which produced plants. In a further study in 1988, Songstad, Duncan & Widholm in Plant Cell Reports (1988), 7: 262-265 reports several media additions which enhance regenerability of callus of two inbred lines. Other published reports also indicated that "nontraditional" tissues are capable of producing somatic embryogenesis and plant regeneration. K. P. Rao, et al., Maize Genetics Cooperation Newsletter, 60: 64-65 (1986), refers to somatic embryogenesis from glume callus cultures and B. V. Conger, et al., Plant Cell Reports, 6: 345-347 (1987) indicates somatic embryogenesis from the tissue cultures of maize leaf segments. Thus, it is clear from the literature that the state of the art is such that these methods of obtaining plants are, and were, "conventional" in the sense that they are routinely used and have a very high rate of success.

Tissue culture of corn is described in European Patent Application, publication 160,390, incorporated herein by reference. Corn tissue culture procedures are also described in Green and Rhodes, "Plant Regeneration in Tissue Culture of Maize," Maize for Biological Research (Plant Molecular Biology Association, Charlottesville, Va. 1982, at 367-372) and in Duncan, et al., "The Production of Callus Capable of Plant Regeneration from Immature Embryos of Numerous Zea Mays Genotypes," 165 Planta 322-332 (1985). Thus, another aspect of this invention is to provide cells which upon growth and differentiation produce corn plants having the physiological and morphological characteristics of the inbred line PHRE1.

Corn is used as human food, livestock feed, and as raw material in industry. The food uses of corn, in addition to human consumption of corn kernels, include both products of dry- and wet-milling industries. The principal products of corn dry milling are grits, meal and flour. The corn wet-milling industry can provide corn starch, corn syrups, and dextrose for food use. Corn oil is recovered from corn germ, which is a by-product of both dry- and wet-milling industries.

Corn, including both grain and non-grain portions of the plant, is also used extensively as livestock feed, primarily for beef cattle, dairy cattle, hogs, and poultry.

Industrial uses of corn are mainly from corn starch in the wet-milling industry and corn flour in the dry-milling industry. The industrial applications of corn starch and flour are based on functional properties, such as viscosity, film formation, adhesive properties, and ability to suspend particles. The corn starch and flour have application in the paper and textile industries. Other industrial uses include applications in adhesives, building materials, foundry binders, laundry starches, explosives, oil-well muds, and other mining applications.

Plant parts other than the grain of corn are also used in industry. Stalks and husks are made into paper and wallboard and cobs are used for fuel and to make charcoal.

The seed of inbred corn line PHRE1, the plant produced from the inbred seed, the hybrid corn plant produced from the crossing of the inbred, hybrid seed, and various parts of the hybrid corn plant can be utilized for human food, livestock feed, and as a raw material in industry.

Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity and understanding, it will be obvious that certain changes and modifications may be practiced within the scope of the invention, as limited only by the scope of the appended claims.

Applicants have made available to the public without restriction a deposit of at least 2500 seeds of Inbred Corn Line PHRE1 with the American Type Culture Collection (ATCC), Rockville, Md. 20852 USA, ATCC Deposit No. 75694. The seeds deposited with the ATCC are taken from the same deposit maintained by Pioneer Hi-Bred International, Inc., 700 Capital Square, 400 Locust Street, Des Moines, Iowa 50309 since prior to the filing date of this application. This deposit of the Inbred Corn Line PHRE 1 will be maintained without restriction 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 effective life of the patent, whichever is longer, and will be replaced if it becomes nonviable during that period.

Claims

1. Inbred corn seed designed PHRE 1 and having ATCC Accession No. 75694.

2. A corn plant produced by the seed of claim 1.

3. Tissue culture of regenerable cells of PHRE1 wherein the tissue regenerates plants having the genotype if PHRE1.

4. A tissue culture according to claim 3, the tissue culture selected from the group consisting of leaves, pollen, embryos, roots, root tips, anthers, silk, flowers, kernels, ears, cobs, husks and stalks, and cells and protoplasts thereof.

5. A corn plant having the genotype of PHRE1 regenerated from the tissue culture of claim 3.

6. Hybrid seed produced by:

(a) planting, in pollinating proximity, seeds of corn inbred lines PHRE1 and another inbred line;

(b) cultivating corn plants resulting from said planting;

(c) preventing pollen production by the plants of one of the inbred lines;

(d) allowing natural cross pollinating to occur between said inbred lines; and

(e) harvesting seeds produced on plants of the inbred line of step (c).

7. Hybrid seed produced by hybrid combination of plants of inbred corn seed designated PHRE 1 and having ATCC Accession No. 75694 and plants of another inbred line.

8. Hybrid plants grown from seed of claim 7.

9. A first generation (F.sub.1) hybrid corn plant produced by the process of:

(a) planting, in pollinating proximity, seeds of corn inbred lines PHRE1 and another inbred line;

(b) cultivating corn plants resulting from said planting;

(c) preventing pollen production by the plants of one of the inbred lines;

(d) allowing natural cross pollinating to occur between said inbred lines;

(e) harvesting seeds produced on plants of the inbred line of step (c); and

(f) growing a harvested seed of step (e).

10. A tissue culture of the regenerable cells of corn plant of claim 8.

11. A tissue culture of the regenerable cells of the corn plant of claim 9.