2018 ASHS Annual Conference

Chile pepper (Capsicum species) has important economic and cultural significance worldwide. One of its most distinctive attributes is the burning sensation when consumed. This heat sensation is caused by a class of alkaloid compounds known as capsaicinoids that typically accumulate in vesicles located on the placental walls of mature fruit. Several studies have been conducted on the genetics of heat inheritance in chile pepper. A single, dominant gene, Pun1, plays a role in the production of capsaicinoids in C. annuum. A second locus is suspected of controlling the production of vesicles in the placental wall. The locus, termed the “loss of vesicle” gene (lov), is the explanation for a no-heat phenotype in some Capsicum species. In this study, a segregating population constructed using two no-heat parents, C. annuum bell-type, ‘Jupiter’, and the commercial F₁ cultivar, ‘Paladin’, were hybridized. ‘Jupiter’ has vesicles and is no-heat. ‘Paladin’ displays a smooth placental wall (i.e., no vesicles) and is heterozygous at the Pun1 locus. The F₁ progeny displayed a hot phenotype, and were selfed and the subsequent F_{2 ­} generation was evaluated. Fruit in the F₂ population segregated displaying 3 phenotypes: hot with vesicles, no-heat with no vesicles, and no-heat with vesicles. The segregation did not fit the expected phenotypic ratio 9:4:3. Results suggest that vesicle production is a quantitative trait. This also proves that capsaicinoid production and vesicles production are independent genes. This study provides further insight into the various modes of heat production in Capsicum and will aid breeding programs with cultivar development.