Application Of Hybrid Technology In Cold-tolerant And High Yield Volvariella Volvacea Strain Selection

Volvariella volvacea is a kind of grass-rot fungi which grows in tropical and subtropical area.It has a broad market for its delicious taste and rich nutrition.There are two main problems in the growth of Volvariella volvacea.One is that its growth region and season are limited due to its sensitivity to temperature,the other is that its biological efficiency is only 10-40%,which is lower than other edible fungi.Breeding high yield and cold-tolerant strains of Volvariella volvacea is an important way to solve the problems mentioned above.We chose Thailand NO.1 and cold-tolerant strain VH3 as parent strains,after crossing,screening by low temperature and molecular identification,we got some potential cold-temperature hybrids.Then we cultivated those hybrids in relatively low temperature(28?),hybrid with high yield and cold-tolerant ability were selected after analyzing of agronomic characters.The study mainly include the following areas.1.The selection of parent strains in cross breeding:The 11 Volvariella volvacea strains have high genetic diversity at molecular level for the genetic distance between them was from 0.0723 to 0.4680.The genetic distance between VH3 and Thailand was 0.3180.The two strains are selected as parent strains for two reasons,one is that VH3 is cold-tolerant strain which has been confirmed,which cold-tolerance ability may pass on to hybrids,the other one was that the large genetic distance between these two strains can bring rich genetic recombination in a large extent.2.Obtaining of cold tolerant strains:We got 600 hybrids from pairwise of 10 VH3 monospore strains and 20 Thailand monospore strains.After treating at 0? for 10 h,the 600hybrids were growed at 32? for recover,hybrids with better recover ability than VH3 were regarded as cold-tolerant strains.We got 132 real hybrids by RAPD molecular identification from 269 cold tolerate strains.3.Fruiting verification:Fruiting test at 28? of 45 hybrid strains and parent strains shows that hybrid strains V6T3-1 and V7T3-1 had biological efficiency of 28.26%,18.57%respectively,which were much higher than parent strains.4.Correlation analysis of agronomic character.Correlation analysis of growth rate of mycelium,transverse diameter,lengthwise diameter,thickness of universal veil,time of primordia initiation,time of picking,biological efficiency shows that the growth rate of mycelium is positive correlated with biological efficiency,it means that the faster the mycelium grows,the higher the yield will be.So we can forecast the biological efficiency through measuring the growth rate of mycelium before breeding.Growth rate of mycelium can illustrate fruiting ability in a certain extent,so we can use this to forcast biological efficiency before fruiting.Time of primordia initiation,time of first harvest are negative correlated with biological,it means that the earlier the primordia initiate,earlier harvesting,the higher the yield strains will be.Early harvest can reduce production time and increase productivity,besides,the strains with this character usually have high biological efficiency.