Mapping Of QTL For Important Nutritive Quality Traits And Mining Of WSC Related Candidate Genes In Sorghum-Sudangrass Hybrid

Quality traits,as important indicators for assessing forage quality,play an indispensable role in forage breeding and targeted improvement.Our research group constructed an ultra-high density genetic linkage map using the F₂ population of Sorghum-sudangrass hybrid in the early stage.On this basis,In this study,QTL mapping technology was used to analyze five important nutritional quality traits,including WSC,NDF,ADF,P and K content of Sorghum-sudangrass hybrid.In addition,candidate genes related to WSC content were mined by the combined analysis of RNA-seq technology.This study can lay a foundation for further research on fine mapping,map based cloning,functional analysis and directional improvement breeding of Sorghum-sudangrass hybrid.The main research findings are as follows:（1）Based on the ultra-high density genetic linkage map of Sorghum-sudangrass hybrid,a total of 198 QTLs（LOD>3.0）were identified,including 16 stable QTLs,mainly distributed in 5 linkage groups,such as LG 3,4,6,7,and 8.The LOD values ranged from3.01 to 4.79,with a contribution rate range of 8.8%to 13.7%.An average of 3.2 QTLs were distributed on each linkage group,among which LG 3 had the most QTLs with 7QTLs,followed by LG 6,where 4 QTL loci were identified,there are three QTLs on LG 7,while LG 4 and LG 8 each have only one QTL.（2）A total of sixteen stable QTLs were identified,including seven primary QTLs,among which the one controlled WSC content was Qwsc-3-2.Three controlled ADF content,namely Qadf-4-1,Qadf-7-1 and Qadf-7-2;three controlled K content,namely Qk-6-3,Qk-6-4 and Qk-8-1,respectively.（3）A total of 9 differentially expressed genes related to WSC content were screened out,After transcriptome sequencing analysis.（4）The combined analysis of QTL mapping results related to WSC traits and transcriptome data showed that Hexokinase-3（hexokinase-3）gene（LOC8081321）was identified as a candidate gene associated with WSC-related synthesis and metabolism.By mining WSC-related genes,the synthesis mechanism of WSC can be explored to provide important data support for the subsequent variety breeding.