Lignan Content And Candidate-gene Association Analysis In Sesame(Sesamum Indicum L.)

Sesame （Sesamum indicum L.） is one of important and high-quality oil crops. Sesame seed is rich of furofuran lignans, such as sesamin, sesamolin, sesamol,that usually are characterized of biological activities.This study tested13candidate genes for lignans biosynthesis in sesame. Based on gene cloning and and sequence alignment, we found that SIN₁007198gene had rich variations among the12high and low lignan sesame accessions. Association analysis was conducted between gene SIN₁007198and lignan contents in a population of86accessions from core sesame collection.1. Candidate genes screening. In comparison with other genes tested, gene SIN₁007198showed greater variation in the12sesame accessions with high or low lignan contents. There were138SNP polymorphic sites in the high lignan-content lines and72in the lows, respectively. After filtering out the same sites,172unique polymorphic sites were retained finally. The sequence polymorphism of gene SIN₁007198was also evaluated using86sesame accessions. Totally69polymorphic sites were identified in the coding region, including58SNPs and11Indels. Among the13candidate genes,12of them were free of uniform differences, so it was speculated that the12genes may not involve in the key pathways of lignan biosynthesis, and there may be genes regulating the lignan biosynthesis.2. Population construction and phenotypic analysis. The86sesame accessions that were picked out from the core sesame collection were used for lignan-content analysis, the test results of2012year and2013year showed sesamin, sesamolin and the sum of the two all had wide variation and exhibited normal distributions. The sesamin contents varied from0.77to8.12mg/g, with coefficient of variation （CV） of27.07%. The sesamolin content varied from0.51to1.72mg/g with CV of21.88%. While in2013year, The sesamin contents varied from0.43to5.69mg/g, with coefficient of variation （CV） of32.11%. The sesamolin content varied from0.65to3.26mg/g with CV of21.19%3. Association analysis. The association analysis detected12polymorphic sites were significantly associated with the sesamin, sesamolin or total lignan in all in2012year. Among these sites,4sites were associated with sesamin and5sites associated with sesamolin content, and all of them contributed more than10%. There were17sites detected in2013year. The site at709bp was significantly associated with sesamin, and the contribution was11.14%. In total,16sites were associated with sesamolin content. Especially, the site711was associated with sesamolin in the both years. These associated sites may be related to the sesame lignan biosynthesis and accumulation. Further study is still need to confirm their functions and to develop reliable functional markers for sesame lignans.