Chili pepper (Capsicum annuum) is a member of the Solanaceae family. It is a widely consumed fruit crop that is used as a spice and a vegetable. Seedless fruits of chili pepper are favoured for their ease of consumption and suitability for processing. However, the absence of seeds can negatively affect fruit size. In this study, quantitative trait locus (QTL) analysis was performed in cross populations derived from a cross between a seedless mutant tane nashi-1 and a commercial large-fruited variety ‘Tongari Power’ to identify genetic loci affecting fruit size of seedless chili pepper. A major QTL on chromosome 7, designated as qFS7, was identified. It was found to be associated with the length, width, and weight of seedless fruit, explaining up to 35.5% of the phenotypic variation. Notably, a more than twofold increase in fruit weight was observed. QTL analysis using a seedy population also detected qFS7, indicating it affects the size of both seedless-fruit and seedy-fruit. Furthermore, evaluation of the QTL genotype in the progeny population confirmed its stable effect on fruit size. Histological analysis of ovary and mature fruit suggested that qFS7 enhanced ovary size by increasing the number of cell layers rather than cell size, leading to an enlarged fruit. Studying qFS7 will provide insights into the mechanisms of Capsicum fruit development and be useful for breeding seedless fruit cultivars with larger fruit size.
Maki et al. (Thu,) studied this question.