Identifying SSR markers associated with seed characteristics in Perilla (Perilla frutescens L.)

Substantial differences exist in seed dormancy between cultivated crops and their wild progenitors. The purpose of this study was to identify simple sequence repeat (SSR) markers associated with seed characteristics in cultivated and weedy types of Perilla crop. By using an association analysis of 29 SSR markers and three seed traits in 38 Perilla accessions, we detected six SSR markers associated with the seed germination rate (SGR), eight SSR markers associated with seed hardness (SH), and seven SSR markers associated with seed size (SS). Among these SSR markers, three (KNUPF3, KNUPF25, KNUPF60) were associated with the SGR, SH, and SS traits. Correlation analysis among the three seed traits of the 38 Perilla accessions showed a positive correlation coefficient for the combination of SGR and SS (0.811**) and a negative correlation coefficient for the combinations of SGR and SH (- 0.706**), and SS and SH (- 0.899**). A phylogenetic tree constructed using the unweighted pair group method with arithmetic mean (UPGMA) revealed that accessions of cultivated P. frutescens var. frutescens could be distinguished from weedy accessions of P. frutescens var. frutescens and P. frutescens var. crispa using the 29 SSR markers. Selected SSR markers related to the three seed traits distinguished accessions of cultivated and weedy types. Therefore, these results are very important for understanding the seed characteristics of cultivated and weedy types of Perilla crop. It will further help for improving the seed quality of Perilla crop through marker-assisted selection (MAS) breeding programs.