Genetic analysis of a Nonpungent EMS mutant in pepper (Capsicum annuum L.)

Abstract

Capsaicinoid is the alkaloid compounds produced in peppers (Capsicum spp.). They are responsible for pepper pungency or hotness and is one of the important traits in breeding programs. Although many studies have been performed to elucidate its biosynthesis, the biosynthetic pathway is largely based on studies on the similar pathways of other plants. To understand the biosynthesis of capsaicinoid, a nonpungent mutant 221-2-1a, developed from pungent 'Yuwol-cho' were analyzed. 221-2-1a was found to have no mutation in the coding sequence of Pun1, but the levels of capsaicinoid in their fruits were drastically decreased compared to that of Yuwol-cho. To identify the gene(s) responsible for the non-pungent trait in 221-2-1a. Gene expressions of 12 genes involved in capsaicinoid biosynthesis were compared between 221-2-1a and Yuwol-cho together with several selected cultivars. Seven out of 12 genes (pAMT, BCAT, ACL, KAS, FatA, PAL, and Pun1) showed a significant decrease in their expression levels in 221-2-1a compared to pungent cultivars. Furthermore, the inheritance of pungency was studied in a population derived from a between Yuwolcho and 221-2-1a. The inheritance study showed that the nonpungency in 221-2-1a is controlled by two recessive genes. To identify the genes responsible for non-pungency trait, samples of Yuwol-cho and bulked F3 were sequenced and analyzed by MutMap. A total of 11 SNPs were identified in the intergenic sequences and the candidates were annotated. Although candidate genes were not capsaicinoid biosynthesic genes, the candidate genes are believed to be ideal targets in studies to carryout in the future.