Studies On Breeding Excellent Hybrid Strains Of Lentinula Edodes Suitable For Industrial Cultivation

Lentinula edodes,one of the main edible fungi in China,has typical medicinal and edible values,and occupies a high proportion in the international and domestic markets.Cultivation with large scale,facility and factory is the development direction of the L.edodes industry.However,along with a series of problems such as spawn degradation,long production cycle and lack of special strains suitable for factory cultivation,existing strains are difficult to meet market demands,and it is imperative to breed L.edodes strains with independent intellectual property rights and suitable for factory cultivation.In the study,with the help of the experimental platform of Shandong Qihe Biotechnology Co.,Ltd.,the wild strain YS44 and the main cultivar "Qihe No.2"(L2)were used as parents.Therefore,the major cultivar was improved by using the characteristics of wild strain with the characteristics of precocity,whose fruiting is early,large number of fruiting bodies,round shape,and thick pileus.Then,a hybrid population containing 363 L.edodes strains was successfully constructed by means of hybrid between monokaryons.Combined with production requirements,two rounds of cultivation experiments were completed using automated production workshops and intelligent production equipment.The main phenotypic traits of each strain at the mycelium stage and fruiting body stage were investigated and analyzed.Nine agronomic traits of the tested strains,including weight of single fruiting bodies(WF),number of fruiting bodies(NF)and yield per cultivation bag(Y)were comprehensively compared,and four hybrid strains of L.edodes suitable for industrial cultivation were finally selected.1.Three hundred and sixty-three hybrid strains were selected for a one-year cultivation experiment,340 of which can form fruiting body normally.Phenotypic traits of the mycelium and fruiting body stages of these 340 strains were then systematically evaluated.Results displayed that the mycelium growth rate in the sawdust(MGR-sd)was between 0.28-0.38cm/d,with coefficient of variation(CV)of5.17%.Results of statistical analysis showed that the trait with the largest CV was NF(46.03%),and the trait with the smallest CV was the time interval(in days)from incubation to harvest of the first fruiting body(FB)(1.34%).The correlation analysis indicated that NF showed a highly significant negative correlation with WF,and NF showed a highly significant positive correlation with Y,and there was no significant correlation between MGR-sd and the yield traits.The traits of mycelium growth period and yield were comprehensively investigated,and the hybrid strains with precocity,large number of fruiting bodies and high yield were selected.Finally,32 L.edodes strains with better comprehensive characteristics were selected and entered into the second screening test.2.A one-year cultivation experiment were carried out for the 32 strains obtained from the second screening test.Statistical analysis was carried out on for nine agronomic traits such as FB,pileus thickness(PT)and NF.Results showed that NF still had largest CV(47.05%),and the trait with the smallest CV was FB(0.85%),which was consistent with the preliminary screening results.The correlation analysis indicated that FB,NF and Y showed a highly significant negative correlation,and pileus weight(PW),pileus diameter(PD),PT,stipe diameter(SD),stipe length(SL)showed a highly significant positive correlation.And the correlation analysis indicated that NF showed a highly significant negative correlation with WF,and NF showed a highly significant positive correlation with Y.The results of factor analysis showed that the variables represented by the nine agronomic traits were divided into three components PW,PD and PT were one component,and SD,SL and WF were one component,FB,NF and Y were one component,which is consistent with the correlation analysis results,indicating that NF and Y are closely related.3.Nine agronomic traits of the 32 L.edodes hybrids were comprehensively evaluated by grey correlation analysis method.Six strains were selected with both highest equal weight correlation degree and weighted correlation degree(YL180,YL127,YL140,YL289,YL188 and YL157)as candidate strains.Then,the 32 strains were evaluated with the phenotypic evaluation criteria set by Qihe Company,and seven hybrid strains(YL127,YL150,YL147,YL180,YL157,YL338 and YL188)with comprehensive evaluation score ≥20 were chose out.Combining results of grey relational analysis,four elite hybrid strains suitable for industrial cultivation were finally selected,including YL127,YL157,YL180 and YL188.4.The clustering results based on phenotypic traits showed that the 32 hybrid strains were divided into two groups,and there were significant differences in NF and Y between them.The hybrid strains were genetically closer to the YS44 parent strain,and some excellent hybrid strains have a tendency to cluster preferentially.The hybrid strains YL127,YL157,YL180 and YL188 bred in this study possess the characteristics of early fruiting,large number of fruiting bodies,and high yield.They are suitable for industrial cultivation as mini shiitake strains,and enrich the special varieties for industrial cultivation of L.edodes.In addition,by exploring the breeding system of excellent strains under the condition of industrial cultivation,it can provide a reference for the selection and breeding of excellent strains of other edible mushroom in industrial cultivation.