| Lentinula edodes is a macrofungus with high edible and medicinal values,whose cultivation originated from China.Genetic improvement of commercial strains is the basis of sustainable development of L.edodes industry.For the quantitative traits of L.edodes controlled by multiple genes,molecular marker-assisted selection by molecular markers linked to quantitative traits is an effective method for genetic improvement of L.edodes strains.At present,the genetic linkage map of L.edodes is mainly based on non-specific molecular markers,which are difficult to correspond to reference genome.In this study,ten agronomic traits of 136 L.edodes strains were surveyed based on the LQ-15 testcross population.110 out of the 136 strains were sequenced by RNA-Seq,and SNP markers were developed to construct a high-density genetic linkage map of L.edodes.QTL mapping of the ten agronomic traits was carried out,and candidate genes controlling agronomic traits were identified for the improvement of L.edodes strains.1.The cultivation experiment of LQ-15 was carried out to determine ten traits,including precocity,traits related to shape of fruiting body and yield.Combined with the cultivation data of the population in 2012,the data in two years were statistically analyzed and corrected by BLUP correction.Statistic analysis showed that the coefficient of variation of pileus weight,stipe weight,weight of single fruiting body and number of fruiting bodies were higher in the two years.Correlation analysis showed that,except for pileus weight,the other nine traits were significantly positively correlated with each other during the two years.The traits related to shape of fruiting body were positively correlated with each other in the two years.In yield traits,the number of fruiting bodies was negatively and positively correlated with weight of single fruiting body and yield of single bag,respectively.The analysis of variance shows that the genotype,year,interaction between genotype and year have a very significant effect on the phenotype of the traits.2.The transcriptomes of mature fruiting bodies in the 110 strains of LQ-15 were sequenced.A high-density genetic linkage map of L.edodes was constructed using a 12083 SNP markers.The total length of the map was 1039.37 cM,including 11 linkage groups,covering 337 scaffolds(27.65 Mb shiitake genome).These SNPs were included in 671 bins.The average distance between markers are 0.11 cM,and that between bins were 1.58 cM.3.The high-density genetic map of L.edodes was used to map QTLs for the three phenotypic datasets of agronomic traits(2016,2012 and BLUP correction).A total of 63 QTLs controlling the ten traits were detected by using compound interval mapping(CIMs).The QTLs were distributed unevenly in eight linkage groups,and most of them were clustered in LG01,LG02,LG03 and LG06.The number of QTLs controlling each trait varied from four to nine.Nine QTLs were identified with high percentages of phenotypic variation explained > 15%.76% of the loci were distributed in nine QTL hotspots.QTLs controlling phenotypic related traits,is clustered in the linkage map,which indicates that these QTLs may be multi-effect or closely linked loci,and QTL collocity is the genetic basis of phenotypic correlation.4.Correlation analysis between gene expression and phenotype was performed to screen candidate genes,a total of 577 candidate genes related to ten traits were detected.Among them,153 genes that control multiple traits simultaneously.37 candidate genes were repeatedly detected by more than 2 QTLs.The candidate genes were identified as homologous to encode glycoside hydrolase,hexose transporter,transmembrane protein,protein kinase and laccase,which may regulate agronomic traits of L.edodes. |
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