Inheritance of Non-pungency in ‘No.3341’ (Capsicum chinense)

Abstract

An understanding of the genetic mechanism underlying capsaicinoid biosynthesis is important for breeding both pungent and non-pungent peppers. Although Capsicum is one of the earliest domesticated plant genera, only mutations in acyltransferase (Pun1) and putative aminotransferase (p-AMT) have been reported as genetic causes of loss of pungency. ‘No.3341’ (C. chinense) from Bolivia is a non-pungent cultivar. To determine the reasons underlying the non-pungency of ‘No.3341’, its expression levels and deduced amino acid sequences of Pun1 and p-AMT were analyzed. In ‘No.3341’, the expression levels and deduced amino acid sequences of both genes were normal compared with those of the pungent cultivar ‘Habanero’. Inheritance of the non-pungency was analyzed in F₁ and F₂ populations obtained by crossing ‘No.3341’ with ‘Habanero’. The segregation ratio indicated that the non-pungency of ‘No.3341’ is controlled by a single recessive gene. Moreover, since F₁ populations obtained by crossing ‘No.3341’ with a non-pungent pepper, ‘NMCA30036’ harboring a mutation in Pun1, or with ‘No.2’ and ‘No.80’ harboring mutations in p-AMT, were all pungent, Pun1 and p-AMT could not account for the non-pungency of ‘No.3341’. It appears that a novel genetic mechanism is responsible for the loss of pungency in ‘No.3341’.