Bunashimeji mushroom named ‘Marmo22go’

Abstract

The present variety of mushroom named ‘Marmo22go’ was cultivated by the gathering and repeated breeding of Bunashimeji mushrooms having dominant traits, which has good qualitative character and appearance, a thick white stem, a large mushroom size, and a resistance to high temperatures. This edible mushroom is exquisite in stability, reproducibility and uniformity when being produced.

Description

BACKGROUND OF THE INVENTION

This invention relates to a new and distinct variety of mushroom of Bunashimeji mushroom, Hypsizygus marmoreus (Peck) Bigelow. This new variety named ‘Marmo22go’ cultivated by repeated breeding of Bunashimeji mushrooms having dominant traits, which has a thick white stem, a large mushroom size, a resistance to high temperatures and ensures presentable stability, reproducibility and uniformity.

Bunashimeji (Hypsizygus marmoreus) now boasts of being the second most consumed edible mushroom after enokitake mushroom in Japan. After bunashimeji was cultivated and became available in the market in large quantities, ‘Hokuto 8gokin’ was developed which reduced the characteristic bitterness of the original bunashimeji. Investigation on tasty bunashimeji was continued even after the development of Hokuto 8gokin, and a variety with improved taste, quality and keeping quality named ‘Hokuto 18gokin’ was developed, which contributed to an increase in consumption.

In order to further improve cultivation stability and the quality of mushrooms, selective breeding was repeatedly carried out by cross-breeding. As a result, a ‘Marmo22go’ mushroom was developed with a thick white stem and larger mushroom size, and a greater resistance to high temperatures, as compared to the ‘Hokuto 18gokin’ mushroom. Subsequently, the stability, reproducibility and uniformity of the variety were verified, and cultivation was completed.

SUMMARY OF THE INVENTION

The present invention is a new and distinct variety of mushroom characterized particularly by its good qualitative character and appearance, a thick white stem, large mushroom size, and a resistance to high temperatures, which can be cultivated by gathering and repeated breeding of fungal strains having dominant traits and is exquisite in stability, reproducibility and uniformity when being produced. This novel and distinct variety of mushroom is identified as ‘Marmo22go’.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a phylogenetic tree illustrating the antecedents of ‘Marmo22go’.

FIGS. 2A and 2B respectively show front and back images of a dual-culture of ‘Marmo22go’ colony.

FIGS. 3A and 3B respectively show front and back images of a dual-culture of ‘Marmo22go’ and ‘Marmo23go’.

FIGS. 4A and 4B respectively show front and back images of a dual-culture of ‘Marmo22go’ and ‘Hokuto 18gokin’.

FIGS. 5A and 5B respectively show front and back images of fungal flora of ‘Marmo22go’.

FIGS. 6A and 6B respectively show front and back images of fungal flora of ‘Marmo23go’.

FIGS. 7A and 7B respectively show front and back images of fungal flora of ‘Hokuto 18gokin’.

FIG. 8 shows an image of a fruit body of ‘Marmo22go’.

FIG. 9 shows an image of a fruit body of ‘Marmo23go’.

FIG. 10 shows an image of a fruit body of ‘Hokuto 18gokin’.

FIG. 11 shows an image of size of mottle of ‘Marmo22go’.

FIG. 12 shows an image of size of mottle of ‘Marmo23go’.

FIG. 13 shows an image of size of mottle of ‘Hokuto 18gokin’.

FIG. 14 shows an image of shape, length and size of stipe of ‘Marmo22go’.

FIG. 15 shows an image of shape, length and size of stipe of ‘Marmo23go’.

FIG. 16 shows an image of shape, length and size of stipe of ‘Hokuto 18gokin’.

FIGS. 17A and 17B respectively show front and back images of a dual-culture of ‘Marmo22go’ and ‘MH025615’.

FIGS. 18A and 18B respectively show front and back images of a dual-culture of ‘Marmo22go’ and ‘MH025616’.

DETAILED DESCRIPTION OF THE INVENTION

The history of the ‘Marmo22go’ mushroom in terms of improvement period and the like are set forth in the following chronological list of each stage of variety improvement:

May 2005: Cultivation of ‘MH025616’ strain.

December 2014: Cultivation of ‘MH025615’ strain.

January 2017: ‘MH025616’ and ‘MH025615’ strains were crossed, and of the obtained strains, a strain of high quality, of the targeted white stem was selected and designated ‘MH025617’. Growing test was repeatedly conducted on ‘MH025617’ and since distinguishability, stability and uniformity were confirmed, the strain was named ‘Marmo22go’ and cultivation was completed. Dual culture performed for ‘Marmo22go’ and ‘MH025615’ and dual culture performed for ‘Marmo22go’ and ‘MH025616’ showed formation of a zone line (FIGS. 17A, 17B, 18A, and 18B).

March 2018: Applied for registration of a new variety to the Ministry of Agriculture, Forestry and Fisheries of Japan.

The above crossing is summarized in the phylogenetic tree illustrated in FIG. 1.

The ‘Marmo22go’ mushroom has the following characteristics: a thick white stem, a large mushroom size, and a resistance to high temperatures.

(1) Comparison with existing variety by dual culture

Dual culture was performed for the ‘Marmo22go’ mushroom and similar varieties so as to examine whether or not a zone line is formed.

• Study method: As an examination method, a potato dextrose agar medium was used, and the ‘Marmo22go’ mushroom and similar varieties were inoculated thereon face to face at an interval of 3 cm, and then culture was performed at 25° C. for 28 days to examine whether or not a zone line was formed.
• Strain used:
  • • ‘Marmo22go’.—Present variety.
    • ‘Marmo23go’.—Variety similar to the present variety.
    • ‘Hokuto18gokin’.—Variety similar to the present variety.
• Results: Zone lines were formed between ‘Marmo22go’ and all other co-cultured varieties (Table 1, FIGS. 2 to 4). This clearly shows that the present mushroom is a new variety.

TABLE 1
Results of dual culture
		Similar varieties
		Marmo23go strain	Hokuto 18gokin
	Marmo22go	+	+
	+ is present and − is absent.
	*Zone line formation was not observed in the dual culture between ‘Marmo22go’ strains.

(2) Culture characteristics of ‘Marmo22go’

• Study method: After inoculating an agar piece of the ‘Marmo22go’ having a diameter of 5 mm in potato dextrose agar, preculture was performed at 25° C. for 4 days and hyphae were regenerated (about 10 mm in diameter), and then culture was performed for 7 days at intervals of 5° C. between 5° C. and 30° C. When the average daily hyphae growth rate was calculated based on a hyphae growth rate for seven days of the culture, it was found that the average hyphae growth rate of ‘Marmo22go’ was the fastest at 25° C. (See Table 2). Further, it was found that the hyphae growth rate of ‘Marmo22go’ was faster than that of ‘Marmo23go’ and ‘Hokuto 18gokin’ at 30° C. (See Table 2). ‘Marmo22go’ was asexually reproduced by inoculating on a potato dextrose agar at Mushroom Research Laboratory of the Hokuto Corporation in Nagano-shi, Nagano, Japan.(3) Morphological characteristics of the ‘Marmo22go’ mushroom in a cultivation example
• Cultivation method:
  • • Container.—An 850 polypropylene bottle (Capacity: 850 ml, diameter 58 mm) was used.
    • Culture medium.—Conifer sawdust, corn cob, rice bran and wheat bran were mixed at the dry weight ratio of 7:3:8:2, and the water content was adjusted to 65%. The culture medium was filled up to the brim of the bottle at the rate of 540±20 g per bottle, and was sterilized at high pressure.
    • Starter culture.—About 20 mL of sawdust starter cultures per bottle was inoculated.
    • Culture.—Culture was performed at 22° C. for 50 to 90 days at 70% moisture.
    • Growth.—After completing the culture, the inoculum is removed, and shifted to a growing room. Development was conducted under a temperature of 15±1° C., at humidity of 95% or more, without exposure to light particularly in the first 14 days, then after the 14th day, 500-1,000 Lx is taken and development is conducted at about 2,000 ppm CO₂ density. The mushroom is harvested when the cap in the center of the stump has sufficiently opened.
• Cultivation results: Table 2 shows the characteristics of the ‘Marmo22go’ and specific difference in characteristics as compared with the similar varieties when culture was performed under the abovementioned conditions. Also, the whole images of the respective fruit bodies, the images of the respective mottles, and the images of the respective stipes have also been attached. (Refer to FIGS. 8 to 16).

TABLE 2
Fungus characteristics Table of Hypsizygus marmoreus
(Peck) Bigelow of Recording and Registration
	Present	Similar variety
	variety		Hokuto
	Marmo22go	Marmo23go	18gokin
Physiological property
Dual culture
Zone line formation	observed	observed	observed
Dislike-touch reaction	—	—	—
Density of hyphae	dense	dense	medium
Mycelial growth	dense	dense	medium
Color of surface of colony	white	white	white
Color of back of colony	pale yellow	pale yellow	pale yellow
Accommodativeness
for temperature
Optimal temperature for	24° C.	24° C.	24° C.
hyphal growth (° C.)
Hyphal growth rate
5° C./mm	0.72 mm	0.58 mm	0.78 mm
10° C./mm	1.37 mm	1.38 mm	1.42 mm
15° C./mm	2.28 mm	1.99 mm	2.33 mm
20° C./mm	3.49 mm	3.00 mm	3.44 mm
25° C./mm	3.96 mm	3.20 mm	3.65 mm
30° C./mm	3.02 mm	2.34 mm	1.61 mm
Morphological property
Cap
Cross sectional shape	rounding	rounding	rounding
	mound	mound	mound
Mottle of the surface	medium	medium	medium
Size of mottle	small	small	medium
Distribution of mottle	whole	whole	whole
Clarity of mottle	very clear	very clear	very clear
Size (diameter)	19.8 mm	19.7 mm	18.8 mm
Color of central area	grey-	grey-	grey-
	brown	brown	brown
	199C	199A	199B
Color of peripheral area	grey-	grey-	grey-
	brown	brown	brown
	199D	199B	199C
Thickness (mm)	8.9 mm	8.7 mm	8.2 mm
Fleshy	medium	medium	medium
Gill
Color	yellow-	yellow-	yellow-
	white	white	white
	158C	158C	158C
Alignment	crinkle	crinkle	crinkle
Width	medium	medium	medium
Density	medium	medium	medium
Stipe
Shape	medium	long and	medium
	thick	thin	thick
Length	49.3 mm	55.7 mm	46.2 mm
Size (diameter)	12.6 mm	10.2 mm	9.5 mm
Color	white	white	white
	155B	155B	155B
Hair	absent	absent	absent
Fleshy	medium	medium	medium
Ratio of maximum diameter of	1.61 mm	1.68 mm	1.55 mm
stem to diameter just below cap
Cultural property
Development of fruit body
Development	strain	strain	strain
Optimal culture period	70 days	90 days	90 days
Length of time from fruit	21.4 days	21.1 days	21.8 days
body-formation promotion to
fruit body harvesting at optimal
temperature
Optimal temperature for	15° C.	15° C.	15° C.
primordial development
Optimal temperature for fruit	15° C.	15° C.	15° C.
body growth
Yield
Yield of fruit body	133.8 g	123.1 g	117.6 g
The number of productive stem	32.8	37.6	40.8
*The employed color chart is R.H.S. Colour Chart, 2007, Fifth edition, prescribed by Royal Horticultural Society, England.

Claims

1. A new, distinct variety of Bunashimeji mushroom as substantially illustrated and described in the specification.