Associations among fruit firmness, morphological traits and RAPD markers in the ‘firm’ tomato mutant

Abstract

The Santa Clara Cultivar is widely known in the tomato-producing region of Viçosa (MG). Recently,tomato plants from the same cultivar with changes in morphological traits and post-harvest fruit characteristicshave been identified. The inheritance study and the allelism test carried out by Schuelter et al. (2002) determinedthat a recessive gene with pleiotropic effects modified the expression of morphological traits, such as the colorof stigma and fruits and the early leaf senescence. This gene, present in the ‘firm’ mutant (frm), was mapped onthe tomato chromosome 10 region - the same region of the lutescent-2 (l-2) gene. However, the identificationand location of the genes that increase the firmness of ‘firm’ mutant fruits remain unknown. Therefore, theobjective of this study was to analyze the inheritance of morphological and firmness characteristics of fruitswhich were modified by the mutation using RAPD markers. Results demonstrated that the genomic regioncomprising the l-2 gene increases the fruit firmness, explaining from 6.27 to 25.09% the phenotypic variationfor this trait along the 15 day-period of storage. However, the AQ16747 and AS8622 markers, mapped at 11.67 and21.67 cM from the mutation frm, indicated that the further they were located from this region, the smallerproportion of the phenotypic variation they had. Thus, we can conclude that that the genomic region flanking thel-2 gene also increases fruit firmness in the ‘firm’ mutant, a trait that has never been associated with this gene.