The Monospore Cross Breeding For The Cold-tolerant And High-yield Volvariella Volvacea Strain

Volvariella volvacea is one of the main cultivated and high-speed development cultivated edible fungi in China which was first found in southeast areas in China. Volvariella volvacea grows in the environment of high temperature and humidity and it has significant commercial value because of its high nutritional value and taste delicious. The cultivation of Volvariella volvacea is high energy consumption and the biological efficiency of Volvariella volvacea is low(only 20%). Both of these,the industrial scale of Volvariella volvacea will get a limited development.The aim of this study is to get the cold-tolerant and high-yield Volvariella volvacea strain with monospore cross breeding. In this study, the high-yield strains were tested by cultivation experiment of 17 Volvariella volvacea strains. And the high-yield strains would be chosen as crossing parent strains with the cold-tolerant strain VH3. Using RAPD analyzed the genetic diversity of the 17 strains. The genetic diversity of strain VH3(Volvariella volvacea)and its single spore isolates(SSIs) was studied in this study. Then the molecular marker of mating-type genes in Volvariella volvacea was used to verify mating-type of Volvariella volvacea monospore strains. At last the techniques of fast screening of the cold-tolerant Volvariella volvacea strain and identification of the hybrid strains using the molecular marker of mating-type genes were used for the cross breeding and the cold-tolerant and high-yield Volvariella volvacea strain VV093 was got. The major results were as follows:1.After the cultivation experiment, mycelial growth rate, time of primordia initiation, time of first harvest, biofilm thickness, length and width of fruit body, biological efficiency were got. High-yield strains were pingyou NO.1, 0229, Vn-1 and Z-V23 with the biological efficiency 21.73%, 18.58%, 16.36% and 15.99% based on the biological efficiency. Because of the thin biofilm thickness, 0229 could not be the parent strain. So the strains pingyou NO.1, Vn-1 and Z-V23 were chose as the parent strains preliminary.2.In the RAPD analysis, 9 random primers which had the good polymorphism and repeatability were chose from 35 initial random primers. The results showed that strains had the genetic differences with the genetic similarity coefficient(about 0.68-1.00). The 17 strains were divided into four main groups when the genetic similarity coefficient was 0.784. There were three types of mating-type genes. Pingyou NO.1 was A1A2, Thailand NO.1, Vn-1and Vn-3 were A5A6, and others were A3A4. At last we chose pingyou NO.1 and Vn-1 as the the high-yield parent strains.3.The colony morphology, the mycelial extension growth rate and the genetic diversity based on RAPD were studied for research the growth and development and the genetic diversity of strain VH3( Volvariella volvacea) and its 14 single spore isolates(SSIs). The studies demonstrated that the significant differences were found the among strain VH3 and its SSIs in the colony morphology and the mycelial extension growth rate. There were two type of the colony morphology which were the aerial type and creeping type and the mycelium growth vigor was different. Also the mycelial extension growth rate among strain VH3 and its SSIs was different and the SSIs V4 and V10 had the highest growth rate. The strain VH3 and its SSIs also showed genetic diversity by the RAPD analysis. 9 random primers which had the good polymorphism and repeatability were chose from 35 initial random primers. The results showed that strain VH3 and its SSIs had the obvious genetic differences with the genetic similarity coefficient(about 0.50). The significant differences of phenotype and genotype in strain VH3 and its SSIs showed that strain VH3 produced abundant biomutations by sexual reproduction.4.In this study we used the molecular marker of mating-type genes in Volvariella volvacea to verify mating-type of Volvariella volvacea monospore strain and completed the monospore cross breeding. Obtaining the hybrid strains using techniques of fast screening of the cold-tolerant Volvariella volvacea strain and identification of the hybrid strains by the molecular marker of mating-type genes. The results showed that the cross breeding method assisted by the molecular marker of mating-type genes was an efficient method to obtain the hybrid strains. Also this method was help to fruiting with high seed setting rate. And VV093 got higher biological efficiency than Pingyou NO.1 or VH3 at 28℃ and they got better cultivation characteristics. So using monospore cross breeding method assisted by the molecular marker of mating-type genes can breed the cold-tolerant and high-yield Volvariella volvacea strains.5.The results of agronomic traits correlation analysis showed that time of primordia initiation was significant positive correlated with time of first harvest. Time of primordia initiation might be significant negative correlated with length and width of fruit body. Time of primordia initiation was significant negative correlated with biological efficiency. Length and width of fruit body might be significant negative correlated with biological efficiency.