Patent Publication Number: US-PP33127-P3

Title: Maitake mushroom named ‘Grifon-8go’

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a new and distinct variety of Maitake mushroom,  Grifola frondosa  (Fr.) S.F.Gray. This new variety named ‘Grifon-8go’ cultivated by repeated breeding of Maitake mushrooms having dominant traits, which has a strong curving cap, enhanced cultivation stability, and a high-yield, and ensures presentable stability, reproducibility, and uniformity. 
     Maitake ( Grifola frondosa ) has long been a popular edible mushroom in Japan, and in recent years, its health benefits have attracted attention and demand for the mushroom is expanding. In the early days of artificial cultivation becoming possible, the difficulty in artificially controlling the cultivation environment suitable for cultivation of maitake had made mass production of the mushroom difficult. Therefore, we developed a variety that is easy to grow, with improved quality, taste, and keeping quality named ‘Hokuto NT-100gokin’ (U.S. Plant Pat. No. 17,984 P3). Subsequently, with the aim of resolving a problem of easy discoloration and poor appearance of the back of the cap present in ‘Hokuto NT-100gokin’, cross-breeding was repeatedly conducted, and a variety with a white back of the cap named ‘Grifon120’ was developed (U.S. Plant Pat. No. 21,575 P3). However, due to the color of the surface of the cap being thin, the ‘Grifon120’ mushroom had a problem of declining freshness, and as a result of further product development, a variety with an enriched cap color and excellent cultivatability named ‘Grifon-7’ was developed (U.S. Plant Pat. No. 25,856 P3). 
     ‘Grifon-7’ has no curving of the edge of the cap, and there was the problem of the cap being easily broken during packaging. Therefore, continuing breed improvement was conducted by cross breeding so as to improve this problem and further enhance cultivation stability, and a new variety, ‘Grifon-8go’, with a strong cap, high quality and excellent cultivatability was developed. 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 strong curving cap of high quality, 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 ‘Grifon-8go’. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a phylogenetic tree illustrating the antecedents of ‘Grifon-8go’. 
         FIGS. 2A and 2B  respectively show front and back images of a dual-culture of ‘Grifon-8go’ colony. 
         FIGS. 3A and 3B  respectively show front and back images of a dual-culture of ‘Grifon-8go’ and ‘Grifon120’. 
         FIGS. 4A and 4B  respectively show front and back images of a dual-culture of ‘Grifon-8go’ and ‘Mori51go’. 
         FIGS. 5A and 5B  respectively show front and back images of fungal flora of ‘Grifon-8go’. 
         FIGS. 6A and 6B  respectively show front and back images of fungal flora of ‘Grifon120’. 
         FIGS. 7A and 7B  respectively show front and back images of fungal flora of ‘Mori51go’. 
         FIG. 8  shows an image of cap thickness and shape at the cross section of the cap of ‘Grifon-8go’. 
         FIG. 9  shows an image of cap thickness and shape at the cross section of the cap of ‘Grifon120’. 
         FIG. 10  shows an image of cap thickness and shape at the cross section of the cap of ‘Mori51go’. 
         FIG. 11  shows an image of the diameter of the fruit body cluster, surface color of cap, and ring shape of ‘Grifon-8go’. 
         FIG. 12  shows an image of the diameter of the fruit body cluster, surface color of cap, and ring shape of ‘Grifon120’. 
         FIG. 13  shows an image of the diameter of the fruit body cluster, surface color of cap, and ring shape of ‘Mori51go’. 
         FIG. 14  shows an image of the formation and color of the surface coating of the culturing mushroom bed of ‘Grifon-8go’. 
         FIG. 15  shows an image of the formation and color of the surface coating of the culturing mushroom bed of ‘Grifon120’. 
         FIG. 16  shows an image of the formation and color of the surface coating of the culturing mushroom bed of ‘Mori51go’. 
         FIG. 17  shows an image of fruit bodies of ‘Grifon-8go’. 
         FIG. 18  shows an image of fruit bodies of ‘Grifon120’. 
         FIG. 19  shows an image of fruit bodies of ‘Mori51go’. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     ‘Grifon-8go’ mushroom was discovered at Mushroom Research Laboratory in Nagano-shi, Nagano, Japan where the temperature, humidity and carbon dioxide gas concentration are controlled. ‘Grifon-8go’ was asexually reproduced by inoculating on a potato dextrose agar with hyphae and incubating in a culture room set at 25° C. The history of the ‘Grifon-8go’ mushroom in terms of improvement period and the like are set forth in the following chronological list of each stage of variety improvement: 
     December 2011: ‘MH182239’ and ‘MH182242’ strains were crossed, and ‘Grifon-7’ was obtained 
     September 2014: ‘Grifon120’ and ‘MH182264’ strains were crossed, and ‘MH182265’ was obtained 
     July 2017: ‘Grifon-7’ and ‘MH182265’ strains were crossed, and the excellent strain ‘MH182266’ was obtained 
     September 2018: Growing test was repeatedly conducted on ‘MH182266’ and since distinguishability, stability, reproducibility and uniformity were confirmed, the strain was named ‘Grifon-8go’ and cultivation was completed. Dual culture performed for ‘Grifon-8go’ and ‘Grifon120’ and dual culture performed for ‘Grifon-8go’ and ‘Mori51go’ showed formation of a zone line ( FIGS. 3A, 3B, 4A, and 4B ). Applied for registration of a new variety to the Ministry of Agriculture, Forestry and Fisheries of Japan. Registered the Application No. 33394 on Sep. 26, 2018. 
     In morphological characteristics, ‘Grifon-8go’ has a thicker cap (2.82 mm) than that of the parent variety, ‘Grifon-7’ (1.79 mm). And the shape of the cross section of the fungus is angled 45 degrees downward in ‘Grifon-8go’, while it is horizontal in the parent variety, ‘Grifon-7’. Also, the color of the back of the fungus is white on ‘Grifon-8go’; on the other hand, it is slightly yellow on the parent variety, ‘MH182265’. 
     The above crossing is summarized in the phylogenetic tree illustrated in  FIG. 1 . 
     The ‘Grifon-8go’ mushroom has the following characteristics: a strong curving cap, enhanced cultivation stability, and a high-yield. 
     (1) Comparison with Analogous Variety by Dual Culture 
     Dual culture was performed for the ‘Grifon-8go’ mushroom and similar varieties so as to examine the tactile reaction. 
     Study Method: 
     In an examination for tactile reaction, a potato dextrose agar medium was used, and the ‘Grifon-8go’ 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 21 days to examine the presence or absence of a tactile reaction. 
     Strain Used: 
     ‘Grifon-8go’: Present variety 
     ‘Grifon120’: Variety similar to the present variety 
     ‘Mori51go’: Variety similar to the present variety 
     Results: 
     A zone line was formed between ‘Grifon-8go’ and similar varieties ‘Grifon120’ and ‘Mori51go’, respectively (Table 1,  FIGS. 3A, 3B, 4A, and 4B ). This clearly shows that the present mushroom is a new variety. 
                     TABLE 1                  Results of dual culture                                 Similar variety   Similar variety   Present variety           ‘Grifon120’   ‘Mori51go’   ‘Grifon-8go’               ‘Grifon-8go’   +   +   −               + is present and − is absent.            
(2) Culture Characteristics of ‘Grifon-8go’
 
(2)-1. Hyphae Temperature Adaptability
 
Study Method:
 
     After inoculating an agar piece of the ‘Grifon-8go’ having a diameter of 5 mm and agar pieces of similar varieties in potato dextrose agar medium, 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 10° C. and 30° C. The average daily hyphae growth rate was calculated based on a hyphae growth rate for seven days of the culture. ‘Grifon-8go’ was asexually reproduced by inoculating on a potato dextrose agar at Mushroom Research Laboratory in Nagano-shi, Nagano, Japan. 
     Study Results: 
     ‘Grifon-8go’&#39;s hyphae growth rate was found to be faster than the similar variety ‘Grifon120’ at 10° C., 15° C., 20° C., 30° C. (See Table 2). 
     (2)-2. Comparison of Fungal Flora 
     Study Method: 
     After inoculating an agar piece of the ‘Grifon-8go’ having a diameter of 5 mm and agar pieces of similar varieties having a diameter of 5 mm on a potato dextrose agar medium, culture was performed at 25° C. for 14 days. 
     Study Results: 
     Regarding thickness of the fungal flora, the flora was thinner in the similar variety ‘Mori51go’ than in ‘Grifon-8go’ (See Table 2). 
     (3) Morphological Characteristics of the ‘Grifon-8go’ Mushroom in a Cultivation Example 
     Cultivation Method: 
     Container: A polypropylene cultivation bag (Square, capacity: 8,500-9,000 cc, caliber: 200-120 mm, height: approx. 440 mm, with aeration filter) was used. A total of 48 bags were used, and 16 bags were repeated 3 times. 
     Culture medium: hardwood sawdust mainly composed of beechwood, and corn bran were mixed at the dry weight ratio of 75:25, and the water content was adjusted to 60-62%. After filling 2.5 kg of medium per bag, high pressure sterilization was performed. 
     Starter culture: About 25 cc of sawdust starter cultures per bag was inoculated. 
     Culture: Culture was performed at 20° C.-25° C., 70-75% moisture, and illuminance of 200-500 lux, and the inoculum is then moved to a development room. 
     Growth: The inoculum and the mushroom bag are shifted to a temperature of 17° C.-18° C., 90-95% moisture, and illuminance of 500-1,500 lux, and growth is prompted. After the growth has reached the filter portion, the filter portion is removed and growth into fruiting bodies is prompted. The mushroom is harvested when the tube at the mushroom back has formed about 2-3 mm from the edge. 
     Cultivation Results: 
     Table 2 shows the characteristics of the ‘Grifon-8go’ and specific difference in characteristics as compared with the similar varieties when culture was performed under the abovementioned conditions. 
     Also, the images of the respective shape of caps, fruit body, surface colors, and ring shapes, and the images of the respective culturing mushroom beds have also been attached. (Refer to  FIGS. 8 to 19 ). 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Fungus characteristics Table of Grifola frondosa (Fr.) S.F.Gray of 
               
               
                 Recording and Registration 
               
            
           
           
               
               
               
            
               
                   
                 Present variety 
                 Similar variety 
               
            
           
           
               
               
               
               
            
               
                   
                 ‘Grifon-8go’ 
                 ‘Grifon120’ 
                 ‘Mori51go’ 
               
               
                   
               
               
                 Hyphae density 
                 slightly dense 
                 slightly dense 
                 slightly dense 
               
               
                 Developmental state of  
                 dense 
                 dense 
                 medium 
               
               
                 aerial hyphae 
                   
                   
                   
               
               
                 Shape of the periphery of  
                 heterogenous 
                 heterogenous 
                 heterogenous 
               
               
                 the fungal flora 
                   
                   
                   
               
               
                 Fungal flora thickness 
                 medium 
                 medium 
                 thin 
               
               
                 Fungal flora surface coloring 
                 none 
                 none 
                 none 
               
               
                 Fungal flora surface shape 
                 smooth 
                 smooth 
                 smooth 
               
               
                 Optimal temperature for  
                 26~28° C. 
                 24~26° C. 
                 26~28° C. 
               
               
                 hyphal growth 
                   
                   
                   
               
               
                 Hyphal growth rate 
                   
                   
                   
               
               
                 10° C./day 
                 1.72 mm 
                 1.28 mm 
                 1.45 mm 
               
               
                 15° C./day 
                 2.34 mm 
                 1.79 mm 
                 2.34 mm 
               
               
                 20° C./day 
                 3.25 mm 
                 2.76 mm 
                 3.48 mm 
               
               
                 25° C./day 
                 4.16 mm 
                 3.54 mm 
                 4.26 mm 
               
               
                 30° C./day 
                 4.03 mm 
                 2.96 mm 
                 3.95 mm 
               
               
                 Fruiting body diameter 
                 21.36 cm 
                 20.25 cm 
                 19.89 cm 
               
               
                 Size of cap (Diameter) 
                 33.78 mm 
                 31.07 mm 
                 37.85 mm 
               
               
                 Thickness of cap 
                 2.82 mm 
                 2.66 mm 
                 2.46 mm 
               
               
                 Shape of cap 
                 fan form 
                 fan form 
                 fan form 
               
               
                 Presence of lacinia on  
                 none 
                 none 
                 none 
               
               
                 edge of cap 
                   
                   
                   
               
               
                 Color on edge of cap 
                 N199B 
                 N200B 
                 200B 
               
               
                 Shape at the cross  
                 angled 45 
                 horizontal 
                 horizontal 
               
               
                 section of cap 
                 degrees 
                   
                   
               
               
                   
                 downward 
                   
                   
               
               
                 Surface color of cap 
                 199B 
                 199C 
                 N199C 
               
               
                 Fleshiness of cap 
                 medium 
                 medium 
                 medium 
               
               
                 Ring shape of the cap surface 
                 periphery 
                 periphery 
                 periphery 
               
               
                 Site of tube growth 
                 whole cap 
                 whole cap 
                 whole cap 
               
               
                 Form of strain base of 
                 thick 
                 thick 
                 thick 
               
               
                 fruit body 
                   
                   
                   
               
               
                 Formation of surface coating  
                 little 
                 slightly little 
                 medium 
               
               
                 on culturing mushroom bed 
                   
                   
                   
               
               
                 Presence of color on the  
                 none 
                 none 
                 present 
               
               
                 surface coating of culturing  
                   
                   
                   
               
               
                 mushroom bed 
                   
                   
                   
               
               
                 Period until primordial  
                 33.79 days 
                 36.08 days 
                 43.48 days 
               
               
                 formation 
                   
                   
                   
               
               
                 Period until peak growth 
                 43.63 days 
                 47.08 days 
                 56.33 days 
               
               
                 Optimal growth temperature  
                 22-24° C. 
                 22-24° C. 
                 20-22° C. 
               
               
                 for fruiting body 
                   
                   
                   
               
               
                 Yield 
                 920.38 g 
                 835.60 g 
                 663.04 g 
               
               
                   
               
               
                 * The employed color chart is R.H.S Colour Chart, 2007, Fifth edition, prescribed by Royal Horticultural Society, England.