Morphological and gene expression characterization of maf-1, a floral chili pepper mutant caused by a nonsense mutation in CaLFY

Chili peppers are important as vegetables and ornamental crops, because of the variety of fruit shapes and colors. Understanding of flower and fruit development in Capsicum is limited compared with closely related Solanaceae crops such as tomato. This study reports a novel malformed fruit mutant named malformed fruit-1 (maf-1), which was isolated from an ethyl methanesulfonate–induced mutant population of chili pepper. maf-1 exhibited homeotic changes in the floral bud, which were characterized by conversion of petals and stamens into sepal-like and carpel-like organs, respectively. In addition, the indeterminate formation of carpel-like tissue was observed. Genetic analysis demonstrated that the causative gene in maf-1 is a nonsense mutation in CaLFY. This is the first characterization of an lfy mutant in Capsicum. Unlike tomatoes, the CaLFY mutation did not affect the architecture of sympodial unit or flowering time but mainly affected the formation of flower organs. Gene expression analysis suggested that a nonsense mutation in CaLFY led to decreased expression of multiple class B genes, resulting in homeotic changes in the flower and fruit. This maf-1 mutant may provide new insights at the molecular level in understanding flower organ formation and the genetic manipulation of fruit shape in chili peppers.