Association analysis of yield, oil and fatty acid content, and main phenotypic traits in Paeonia rockii as an oil crop

Tree peony has been recently recognised as an oil crop in China. To identify the molecular markers associated with nine important oil-related traits, we performed association analysis among 205 P. rockii genotypes for three consecutive years using 102 polymorphic simple sequence repeats (SSRs). As a result, the phenotypic traits showed higher coefficient of variation (CV) level ranged from 7.47% to 72.76%. Based on the general linear model (GLM, Q) and mixed linear model (MLM, Q + K), the marker-trait associations were different; however, a total of 74 allelic variations were repeatedly detected in all the three consecutive seasons, with 15 SSR markers associated with five traits, such as yield per plant (Y), the number of valid fruits per plant (PFN), the produced seed ratio (YFWR), hundred seed weight (HKW), and linolenic acid content (LA). In conclusion, the SSR markers ps207, ps328 and ps356 associated with Y, and ps345 associated with LA, which would provide an efficient reference for oil tree peony breeding.