| Castor bean(Ricinus Communis L.),annual or perennial herbaceous plant,is one of the high oil content species in the world,which is originated in Africa.Castor bean seeds oil and its derivatives are widely used in industrial and chemical fields.Still now castor bean industry was depressed due to the lack of castor bean with high yields.To cultivate the castor bean varieties with high yields will facilitate the development of castor bean industry.Capsule cracking is an important yield trait of castor bean.Cracking percentage is closely correlated with endocarp thickness,i.e.the thicker the endocarp is,the more easily cracking occurs.Therefore,to investigate the genetic mechanism of endocarp thickness is helpful to cultivate high yielding castor bean variety with crack resistance.Here we performed a data analysis of a natural population of 405 castor materials for two consecutive years(including 180 local varieties,199 breeding lines,and 26 wild African castor bean),combined with Illumina Hiseq X-Ten resequencing data and whole-genome association studies to locate key genes of yield traits like endocarp thickness.Main findings are listed as follows:1.Endocarp thickness of 405 castor materials displays phenotypic variations between two years.Based on the phenotypic data and SNPs,we identified 4 loci significantly associated with endocarp thickness using EMMAx program.We further found two candidate genes LOC8272207 and LOC8272215 in three endocarp thickness GWAS loci,among which LOC827220 7 is identical to one gene(AT5G20260)encoding xylosyltransferase in Arabidopsis.2.Based on GWAS analysis results,we cloned the LOC8272207 gene and check its expression levels in different tissues of castor bean.RT-PCR results showed that it is strongly expressed in roots and flowers,weakly expressed in fruits.3.Preliminary study showed that:(1)Lignin levels in 1111 material with thick endocarp and easy cracking traits more than that of 2850 material with thin endocarp and crack resistant.Moreover,the expression levels of LOC8272207 in 1111 were significantly higher than that of 2850.(2)Knockdown of LOC8272207 by VIGS method drastically caused the lignin biosynthesis.But the effects of this gene on capsule cracking needs to be experimentally testified in the near future. |
