Genetic variation, correlation, and association mapping of seed yield and its component traits in sesame

Sesame is an important and specific oilseed crop with high quality. Here, we systematically investigated the relationships between plant seed yield (PSY) and nine related traits in 369 sesame core accessions under five environments. The PSY and related traits had general heritability ranging from 14% for PSY to 72% for height to the first capsule (FCH) and final flowering stage (FFS). Correlation analysis suggested that seven yield-related traits, including capsule number per plant (CNP, r = 0.67), capsule stem length (CSL, 0.56), thousand-seed weight (TSW, 0.26), plant height (PH, 0.24), FFS (0.17), initial flowering stage (IFS, - 0.16) and FCH (- 0.14) were the key factors associated with seed yield in sesame (P < 0.01). For the uniculm and branching groups, CNP, CSL, and TSW were the common key factors. Path analysis showed similar direct effects of these key factors on PSY. Association mapping identified 13 simple sequence repeat (SSR) markers significantly associated with the nine seed yield-related traits (P < 0.001). Among these, three SSR markers were repeatedly detected in two environments. Marker Hs635 was associated with the seed number per capsule (SNC). Hs345 was associated with the CNP. Hs618 was associated with the IFS in uniculm accessions. These results provide insights into the traits that influence PSY and their genetics in sesame.