Abstract:
A new and distinct variety of mushroom, named Hokuto NT-100, is described, which mushroom has the following characteristics: large cap, thick meat, nice consistency, nice taste, uniform growth when cultivated in a facility, and suitable for bottle cultivation. The variety of mushroom named Hokuto NT-100 was developed from mushrooms related to Hokuto MY-95 and Hokuto MY-75, which are registered varieties of a Japanese corporation and a wild variety found in Aomori Prefecture of Japan.

Description:
BRIEF SUMMARY OF THE INVENTION 
   The present invention relates to a new and distinct variety of mushroom having the following characteristics: large cap, thick meat, nice consistency, nice taste, uniform growth when cultivated in a facility, and suitable for bottle cultivation. The new variety of mushroom named Hokuto NT-100 was developed from mushrooms related to Hokuto MY-95 and Hokuto MY-75, which are registered varieties of a Japanese corporation, and a wild variety found in Aomori Prefecture of Japan. 
   Latin name of genus and species and variety denomination of the claimed plant: The Latin name of the genus and species of ‘Hokuto NT-100 mushroom’ is  Grifola frondosa  (Dicks, ex Fr.) S. F. Gray, this mushroom is generally called “Maitake” in Japan and seems to be called “hen of the woods” in English. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a top view of the Hokuto NT-100 mushroom; 
       FIG. 2  is an oblique view of the Hokuto NT-100 mushroom; 
       FIG. 3  is a partial side view of the Hokuto NT-100 mushroom; 
       FIG. 4  is an oblique view of the Hokuto NT-100 mushroom in bottle cultivation; 
       FIG. 5  is a side view of the Hokuto NT-100 mushroom in bottle cultivation; 
       FIG. 6  is a top view of the Hokuto NT-100 mushroom in outdoor cultivation; 
       FIG. 7  is a top view of the Hokuto MY-95 mushroom for the purposes of comparison; 
       FIG. 8  is a side view of the Hokuto MY-95 mushroom; 
       FIG. 9  is a top view of the Hokuto MY-95 mushroom in outdoor cultivation; 
       FIG. 10  is a top view of the MH18211 mushroom for the purposes of comparison; 
       FIG. 11  is a side view of the MH18211 mushroom; 
       FIG. 12  is a top of the MH18211 mushroom in outdoor cultivation, and 
       FIG. 13  is a chart showing the system which resulted in the Hokuto NT-100 mushroom. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The history of the Hokuto NT-100 mushroom in terms of improvement period and the like are set forth in the following chronological list of each stage of variety improvement:
     January 1993: By crossing MH18206 amd MH18215, the following three fugal strains were obtained: Hokuto MY-75, Hokuto MY-95 and GD99.   February 1995: Hyphae were obtained from Hokuto MY-75 and GD99.   March 1995: By crossing the hyphae of Hokuto MY-75 and GD99, MH182114 was obtained.   May 1996: From Hokuto MY-95, hyphae were obtained.   June 2000: From MH18284, hyphae were obtained.   August 2000: By crossing the hyphae of MH18284 and MY-95, MH182113 was obtained.   November 2000: From MH182114, hyphae were obtained.   July 2001: From MH182113, hyphae were obtained.   January 2002: By crossing the hyphae of MH182113 and MH182114, a superior variety MH182115 was obtained.   March 2002 to March 2003: Tests were repeated to identify the characteristics of MH182115, and during this time, it was found that bottle cultivation was favorable, and stability, uniformity and differentiability were confirmed. In November 2002, MH182115 was named Hokuto NT-100 and variety improvement was completed. More tests were conducted after that, and characteristics tests were completed in March 2003. The claimed cultivar is stable and reproduces true to type in successive generations of asexual reproduction.   

   The system which resulted in the Hokuto NT-100 mushroom is shown in the flow chart of FIG.  13 . 
   The Hokuto NT-100 mushroom has the following characteristics: large cap, thick meat, nice consistency, nice taste, uniform growth when cultivated in a facility, and suitable for bottle cultivation. 
   The differences between the new variety and its parents are as follows: 
   The parent varieties are MH182113 and MH182114. Both the parent varieties; and the instant new variety of this application can be defined being different genetically because they show a positive reaction in a dual culture. The new variety is different from MH182113 in cultural characteristics in that the new variety can be yielded numerously and has a different cap color. The new variety differs from MH182114 in yield, cap color and number of cilia on the cap. The differences therebetween are summarized in the following table. 
   
     
       
             
           
             
             
             
             
           
             
             
             
             
           
         
             
               TABLE 1 
             
           
           
             
                 
             
             
               Morphological Differences 
             
           
        
         
             
                 
               Instant New Variety 
               MH182113 
               MH182114 
             
             
                 
                 
             
           
        
         
             
               Yield (grams) 
               547.1 
               350.0 
               787.8 
             
             
                 
                 
                 
               Dark gray-brown 
             
             
               Cilia on the cap 
               Small 
               Small 
               Large 
             
             
                 
             
           
        
       
     
   
   When Hokuto NT-100 was cultured with commercially available varieties, inhibition zones were seen. In addition, the optimal temperature for hyphal growth was approximately 24 degree C. 
   The morphological characteristics of Hokuto NT-100 are as follows: at the time of harvest, the cap is fan-shaped or circular; the margin is rounded off; hair is minimal; pore shape is elliptical (Type 1); and pore cross section is uneven. When naturally cultivated, the mode of development is medium and development occurs in September. Experimental data have also shown that the length of time from inoculation to development is 63 days; the optimal development temperatures is 18-20 degree C.; the optimal growth temperature is 17-18 degree C.; and yield is 547.2 g. 
   With regard to other characteristics, the vitamin D 2  content of Hokuto NT-100 was high at 20.6 mg/100 g (international units: 824 IU) according to experimental data. 
   Some of these characteristics tests for Hokuto NT-100 as compared to similar mushroom varieties Hokuto MY-95 and MH18211 (Mori Sangyo #51) are summarized in the following table: 
                                                                                                                         TABLE 2                           Characteristic code of filed variety            Characteristics   01   02   03   04   05               Genetic       Dual culture       Dislike-touch reaction       Physiology       Mycelial growth       Effect of temperature       The optimum (° C.)   22   23   24   25   26       Growth rate       10° C.       15° C.       20° C.       25° C.       30° C.       35° C.       Mycelial color   white       shape of the surface of   smooth   tough       the colony       Shape of colony edge   regular       colony thickness           thin       medium       Density of hyphae           sparse       medium       Cultivation       characteristics       Capsule formation           little       medium       Capsule coloration   Absent       Length of time until   &lt;30   31˜   41˜   51˜   61˜       fruit body fromation at       40   50   60   0       optimal temperature       Development period (natural       cultivation)       Optimal development   &lt;15   15˜   20˜   &gt;25       temperature (C.)       20   29       Optimal fruit body   &lt;18   18˜   &gt;21       growth temperature       21       (C.)       Other       Budding period (natural           Early       inter-       cultivation)                   mediate       Yield (g/bottle)       Morphology       Cap       Size           small       medium       Thickness           Thin       medium       Notch   Absent       Cross sectional shape   1   2   3       Face color   W   G-W   D-G   B   D-B       Annulus   1   2   3   4       Hair           fair       medium       Tube       Shape of tube face   1   2   3   4       Unevenness of cross   Absent       sectional the tip of       tube       Tube position   1   2   3       Stipe shape   1   2   3                        Characteristic code of               filed variety   Note            Characteristics   06   07   08   09   (Data)               Genetic       Dual culture       Dislike-touch reaction               +   −       Physiology       Mycelial growth       Effect of temperature       The optimum (° C.)   27   28   29   30   24° C.       Growth rate       10° C.                   0.8       15° C.                   1.7       20° C.                   2.4       25° C.                   2.6       30° C.                   1.0       35° C.                   0.1       Mycelial color               other   white       shape of the surface of               other   smooth       the colony       Shape of colony edge               regular   irregular       colony thickness       thick           thick       Density of hyphae       dense           sparse       Cultivation       characteristics       Capsule formation       much           medium       Capsule coloration               present   absent       Length of time until   &gt;70               63 days       fruit body fromation at       optimal temperature       Development period (natural                   6 month       cultivation)       Optimal development                   18˜20° C.       temperature (C.)       Optimal fruit body                   17˜18° C.       growth temperature       (C.)       Other       Budding period (natural       Late           intermediate       cultivation)       Yield (g/bottle)                   547.2 g       Morphology       Cap       Size       large           56.4 mm       Thickness       Thick           2.6 mm       Notch               present   Absent       Cross sectional shape                   type 2       Face color               other   dark Brown       Annulus               other   type 3       Hair       many           few       Tube       Shape of tube face               other   type 1       Unevenness of cross               present   present       sectional the tip of       tube       Tube position               other   type 3       Stipe shape               other   type 2                        Code of the similar           variety                    Hokuto MY-               Characteristics   95   HM18211                       Genetic           Dual culture           Dislike-touch reaction   09   09           Physiology           Mycelial growth           Effect of temperature           The optimum (° C.)   04   05           Growth rate           10° C.   0.9   0.8           15° C.   1.4   1.8           20° C.   1.6   2.5           25° C.   2.0   2.9           30° C.   1.2   2.7           35° C.   0.1   0.2           Mycelial color   01   01           shape of the surface of   01   01           the colony           Shape of colony edge   01   09           colony thickness   05   03           Density of hyphae   03   03           Cultivation           characteristics           Capsule formation   05   05           Capsule coloration   01   09           Length of time until   05   06           fruit body fromation at           optimal temperature           Development period (natural   6 month   7 month           cultivation)           Optimal development   02   02           temperature (C.)           Optimal fruit body   01   01           growth temperature           (C.)           Other           Buding period (natural   05   05           cultivation)           Yield (g/bottle)   575.9 g   338.9 g           Morphology           Cap           Size   07   07           Thickness   05   05           Notch   01   09           Cross sectional shape   02   02           Face color   Grayish   Grayish               brown   yellow           Annulus   03   02           Hair   03   03           Tube           Shape of tube face   02   01           Unevenness of cross   09   09           sectional the tip of           tube           Tube position   03   03           Stipe shape   02   01                        
The numbers used to describe the characteristics of the cross-sectional shape, annulus, shape of tube face and the others of the instant new variety are indicative of the morphological types prescribed in the Examination Standard stipulated officially in Japan. Distinguishable characteristics of Hokuto NT-100 are set forth in the following:
 
   When cultured with Hokuto MY-95, an inhibition zone is seen. Hokuto NT-100 is different from Hokuto MY-95 in the following characteristics: optimal growth temperature is 24 and 26 degree C., respectively; meat thickness is thick and regular, respectively; yield is 547.2 and 575.9 g, respectively; cap surface color is dark red and grayish brown, respectively; and pore surface shape is type 1 and 2 prescribed in the Examination Standard officially stipulated in Japan, respectively. When cultured with MH18211, an inhibition zone is seen. Hokuto NT-100 is different from MH18211 in the following characteristics: optimal growth temperature is 24 and 28 degree C., respectively; margin shape is irregular and regular, respectively; meat thickness is thick and regular, respectively; bottom capsule is present and absent, respectively; length of time from inoculation to development is 63 and 73 days, respectively; length of time for natural development is 6 and 7 months, respectively; yield is 547.2 and 338.9 g, respectively; cap gill is present and absent, respectively; cap surface is color dark red and grayish yellow, respectively; annellation type is 3 and 2, respectively; and cross section shape of stipe is type 2 and 1, respectively. 
   The above comparative test results were based, at least in part, on the following tests where the cultivation conditions under which the above-mentioned characteristic tests were conducted were as follows:
         a. Cultivation site: Nagano, Japan.   b. Cultivation period: March 2002 to March 2003.   c. Cultivation methods (location, facility, medium, cultivation mode, scale, etc.). Mushrooms listed in the test results were cultivated using conventional methods in a culture room with 300 containers and a growth room with 300 containers. In the characteristics tests, cultivation was performed using ten bags per block and the cultivation experiment was repeated twice.       The following tests were conducted:
           (   1   )  Dual culture. —Conducted according to the examination standards for mushrooms where characteristics were observed on Difco PDA medium. The strains used were: MH18211 Commercial strain (Mori Sangyo #51). MH182113 mating strain. MH182114 mating strain. MH18284 Wild type. Hokuto MY-75. Hokuto MY-95. MH18212 Commercial strain (Fujimoto sangyou M10). MH18222 Commercial strain (Tochiokimaitake). MH148261 Commercial strain (Tokatiana). With regard to the dislike-touch reaction, the results were as follows where + is present and − is absent.       
       

   
     
       
             
             
           
             
             
             
           
         
             
                 
               TABLE 3 
             
             
                 
                 
             
             
                 
               Hokuto NT-100 
             
             
                 
                 
             
           
           
             
                 
             
           
        
         
             
                 
               Hokuto NT-100 
               − 
             
             
                 
               MH18211 
               + 
             
             
                 
               MH182113 
               + 
             
             
                 
               MH182114 
               + 
             
             
                 
               MH18284 
               + 
             
             
                 
               Hokuto MY-75 
               + 
             
             
                 
               Hokuto MY-95 
               + 
             
             
                 
               MH18212 
               + 
             
             
                 
               MH18222 
               + 
             
             
                 
               MH148261 
               + 
             
             
                 
                 
             
           
        
       
     
       
       
         
           
             
               (   2   )  Mycelial growth. —The growth of Hokuto NT-100 was compared with Hokuto MY-95 and MH18211. 
             
           
         
       
     
  
   
     
       
             
             
             
             
             
             
             
           
         
             
               TABLE 4 
             
             
                 
             
             
               temperature (° C.) 
               10 
               15 
               20 
               25 
               30 
               35 
             
             
                 
             
           
           
             
               Hokuto NT-100 (mm/day) 
               0.8 
               1.7 
               2.4 
               2.6 
               1.0 
               0.1 
             
             
               Hokuto MY-95 (mm-day) 
               0.9 
               1.4 
               1.6 
               2.0 
               1.2 
               0.1 
             
             
               MH18211 (min/day) 
               0.8 
               1.8 
               2.5 
               2.9 
               2.7 
               0.2 
             
             
                 
             
           
        
       
     
   
   
     
       
             
             
             
             
             
             
             
             
           
         
             
               TABLE 5 
             
             
                 
             
             
               temperature (° C.) 
               20 
               22 
               24 
               26 
               28 
               30 
               optimum temp. 
             
             
                 
             
           
           
             
               Hokuto NT-100 (mm/day) 
               2.3 
               2.5 
               2.6 
               2.5 
               2.1 
               1.3 
               24 
             
             
               Hokuto MY-95 (mm-day) 
               1.6 
               1.8 
               2.1 
               2.2 
               2.0 
               1.9 
               26 
             
             
               MH18211 (mm/day) 
               2.4 
               2.8 
               3.0 
               3.2 
               3.3 
               3.2 
               28 
             
             
                 
             
           
        
       
     
       
       
         
           
             
               (   3   )  Characteristics data. —Cultivation data for Hokuto NT-100 was compared with Hokuto MY-95 and MH18211. 
             
           
         
       
     
  
   
     
       
             
             
             
           
             
             
             
           
         
             
               TABLE 6 
             
             
                 
             
           
           
             
               Characteristics 
               Hokuto NT-100 
               Hokuto MV-95 
             
             
                 
             
             
               Capsule formation 
               Medium 
               Medium 
             
             
               Capsule coloration 
               Absent 
               Absent 
             
             
               Length of time until fruit body 
               60-63 days 
               60-63 days 
             
             
               formation at optimal temperature 
             
             
               Optimal development 
               18-21 C. 
               18-21 C. 
             
             
               temperature 
             
             
               Optimal fruit body growth 
               17-18 C. 
               17-18 C. 
             
             
               temperature 
             
             
               Development period (natural 
               September 
               September 
             
             
               cultivation) 
             
             
               Yield 
               574.2 ± 2.6 g 
               575.9 ± 53.8 g 
             
             
               Cap size 
               56.4 ± 16.5 mm 
               43.6 ± 15.8 mm 
             
             
               Cap thickness 
               2.6 ± 0.4 mm 
               2.6 ± 0.5 mm 
             
             
               Cap surface color 
               Dark yellowish red 
               Grayish brown 
             
             
                 
               (1910) 
               (1919) 
             
             
                 
             
           
        
         
             
                 
               Characteristics 
               MH18211 
             
             
                 
                 
             
             
                 
               Capsule formation 
               Medium 
             
             
                 
               Capsule coloration 
               Present 
             
             
                 
               Length of time until fruit body 
               71-73 days 
             
             
                 
               formation at optimal temperature 
             
             
                 
               Optimal development 
               18-20 C. 
             
             
                 
               temperarure 
             
             
                 
               Optimal fruit body growth 
               17-18 C. 
             
             
                 
               temperature 
             
             
                 
               Development period (natural 
               September 
             
             
                 
               cultivation) 
             
             
                 
               Yield 
               338.9 ± 44.7 g 
             
             
                 
               Cap size 
               45.1 ± 10.9 mm 
             
             
                 
               Cap thickness 
               2.6 ± 0.5 mm 
             
             
                 
               Cap surface color 
               Grayish yellow 
             
             
                 
                 
               (2212) 
             
             
                 
                 
             
           
        
       
     
       
       
         
           
             
               (   4   )  Temperature data. —Data for the optimum development temperature of Hokuto NT-100 was determined using conventional cultivation methods where fungal development was monitored at different temperatures, the results being as follows: 
             
           
         
       
     
  
                             TABLE 7                   Primordium formation at each development temperature            Development temperature (C.)   Hokuto NT-100               &lt;15   Primordium formation occurred 61 days           after inoculation       16-20   Primordium formation occurred 56 days           after inoculation       21-25   Low pigmentation on the culture           medium surface       &gt;25   No budding                    
As shown in Table 7, while primordium formation occurred at temperatures below 20° C., when considering cultivation style and productivity, earlier primordium formation is desirable. Therefore temperatures between 16 and 20° C. were suitable, and, in this temperature range, development was most favorable at 18-20° C.
 
   (4) Vitamin D2 Content. 
   The vitamin D2 content in the fruit body was measured with HPLC and the results were as follows: 
   
     
       
             
             
             
             
           
             
             
             
             
           
         
             
                 
               TABLE 8 
             
             
                 
                 
             
             
                 
               Hokuto 
                 
                 
             
             
                 
               NT-100 
               Hokuto MY-95 
               HM18211 
             
             
                 
                 
             
           
           
             
                 
             
           
        
         
             
               The vitamine D2(μg/100 g) 
               20.6 
               15.6 
               7.1 
             
             
               The vitamine D2(IU/100 g) 
               824.0 
               624.0 
               280.0 
             
             
                 
             
           
        
       
     
   
   With regard to asexual reproduction of the subject mushroom:
         (1) The fungal strains in question are preserved at 5° C. on agar slant culture (agar medium) and continuously cultivated once a year.   (2) The medium is a potato dextrose agar culture (PDA) made of 200 grams of potato, 20 grams of glucose, and 15 grams of agar so as to have a pH value of 5.5 in 1 liter of distilled water.   (3) The cultivation of strains is carried out by picking out mycelial fragment from the fungal strains preserved in (1) mentioned above and put on the medium of (2). Then, the strains are cultivated at about 25° C. for 14 days. After bacterial threads of the strains preserved, the strains are displanted to an incubation medium.       

   In a case of preserving the strains once again, the strains thus cultivated may be restored to the process (1) above. 
   The characteristic colors of parts of the instant new variety are recited herein based on Japan Color Standard for Horticultural Plant (JHS Color Chart).