A spontaneous eggplant (Solanum melongena L.) color mutant conditions anthocyanin-free fruit pigmentation

Abstract

We identified a single plant in a grow out of the eggplant (Solanum melongena L.) variety ‘Black Beauty’ bearing green fruit. ‘Black Beauty’ normally produces violet/ black pigmented fruit attributed to anthocyanin accumulation. We selected the greenfruited true-breeding genotype E13GB42 from the S2 generation obtained from selfing of the S0 green-fruited color mutant. Characterization of 12 simple sequence repeat (SSR) markers, eight fruit morphological attributes and fruit yield support E13GB42 arising as a spontaneous mutant of ‘Black Beauty’. With the exception of fruit calyx prickliness, E13GB42 was not significantly different from ‘Black Beauty’ for fruit morphological attributes and yield. E13GB42 exhibited an SSR marker profile identical to that of ‘Black Beauty’ but polymorphic with that of eight violet/black-fruited modern eggplant hybrids, older open-pollinated varieties and landraces. Transcript levels of key anthocyanin biosynthetic genes (Chs, Dfr, and Ans) and regulatory genes (MybC, Myc, and Wd) were significantly lower in the green-fruited E13GB42 mutant in comparison with the blackfruited variety ‘Black Beauty’ at various stages of fruit development ranging from small post-anthesis fruit to full-size marketable fruit. Progeny obtained from selfing of the original mutant and reciprocal crosses with ‘Black Beauty’ produced violet, green, and green with violet striped color classes that together were not compatible with one or two gene inheritance models, suggesting that the mutation responsible for the E13GB42 phenotype influences multiple genetic factors that control fruit pigmentation.