| Vegetable soybean,also known as edamame or ‘maodou’ in China,is a soybean harvested at the R6 growth stage(full pod)when the seeds are still immature and green but are fully developed inside the pods.It is deeply loved by people due to its rich nutrition,unique flavor,and biological activities such as regulating the intestines and lowering blood pressure.The edible quality of vegetable soybeans include sweetness,umani,texture,etc.,which is a research emphasis on vegetable soybean quality.The edible quality of vegetable soybean is affected by multiple chemical components.The research on edible quality of vegetable soybean at home and abroad mainly focused on the content change of chemical components,the accumulation trend and external influencing factors.Based on 287 natural population resources of vegetable soybean from different regions,this project measured the edible quality of vegetable soybean by electronic tongue,and conducted genome-wide association analysis combined with genomic data to find relevant loci with edible quality traits.Several germplasm were selected with high edible quality according to the results of electronic tongue.In addition,metabolomic analysis was conducted on extreme materials to clarify the differential metabolites and metabolic pathways related to sweet and umami taste.The results help us to comprehensively understand the edible quality differences and metabolic regulation mechanism of vegetable soybean,and provide data basis for quality control and theoretical basis for molecular marker assisted breeding in the future.The main results are listed as follows:(1)There were significant differences in the composition and content of amino acids,sugar components and volatile components among the six vegetable soybeans came from six cities in Jiangsu Province.1-octene-3-ol,hexanal,nonal,2-octenal and 2-heptenal were considered to be the main volatile components in vegetable soybeans.The results of electronic tongue showed that Sudou 18 had the highest umami response value(2947.47),and Tong 7-391-1 had the highest sweet response value(3472.11).According to principal component analysis and correlation analysis,the electronic tongue could distinguish different varieties of vegetable soybean and had high consistency with the results of artificial sensory evaluation in sweetness and umami.The correlation coefficient of umami reached 0.926,and the correlation coefficient of sweetness was 0.983.(2)This study analyzed electronic tongue values,coefficient of variation and correlation relationship of different tastes of 287 vegetable soybean populations.287 vegetable soybean germplasm were divided into three groups through cluster analysis,and the five lowest and highest germplasm were selected for each taste.Genome-wide association study was performed by using the phenotypic data of edible quality and genomic data.Ten SNPs associated with edible quality were identified,and 43 genes were screened as potential candidates for controlling edible quality of vegetable soybean,including Glyma.20g035400 which encoding serine/threonine kinase,soybean meal protein lectin,glucanase and glycoside hydrolases,etc.(3)Based on non-targeted metabolomics,a total of 1461 known metabolites were identified from 4 vegetable soybeans with extreme sweetness and umimi values,mainly including compounds with biological roles,lipids and phytochemical compounds.The metabolic compounds in vegetable soybean with different umami and sweetness showed certain metabolic characteristics.Differences are mainly regulated by amino acid metabolism,including sweet and umami amino acids such as alanine,serine,aspartate,glutamic acid,etc.These metabolites mainly involved in arginine metabolism and glutathione metabolism.The differential metabolites related to the biosynthesis of sweet substances were6-phosphogluconate and gluconate,which were mainly involved in starch and sucrose metabolism and in the pentose phosphate pathway.The main reason for the difference of sweetness between TX 023 and TX 540 was the arginine metabolism of amino acids as well as glutathione metabolism,and also related to starch and sucrose metabolism.The difference of umami between TX 023 and TX 373 was mainly due to arginine metabolism as well as glutathione metabolism,and the pentose phosphate pathway involving histidine and gluconic acid.Moreover,according to the analysis of metabolome and genome,among the 31 candidate genes of umami and sweetness,13 were involved in glucose metabolism and amino acid metabolism,including the candidate gene of sweetness Glyma.03g096900 encoding asparaginase,which was involved in the glycolysis pathway.The candidate gene of umami Glyma.20g035400 encodes serine/ threonine kinase,glucanase and glycoside hydrolase,which was involved in metabolic pathways such as arginine metabolism,glutathione metabolism and pentose phosphate. |
