Coloração e firmeza de frutos em híbridos de tomate em função dos alelos rin, nor, norA, og c e hp

Abstract

Because of its perishability, tomato fruit demands quick post harvest commercialization. Tomato fruit ripening is a result of physiological and biochemical changes that ultimately are responsible fruit organoleptic quality. Fruit ripening may be influenced by both genetic background and the presence of mutant alleles. Ripening mutant alleles (rin, nor and norA) increase post-harvest fruit shelf life, but may impair final fruit color. Deployment of these alleles along with color enhancing mutants (hp, ogc) may contribute to increase lycopene content and therefore to obtain tomatoes with improved fruit color. The purpose of this work was to identify tomato hybrid combinations with both good fruit firmness and improved color, as a function of the simultaneous deployment of ripening mutant and color enhancing alleles. Twelve genotypes with genotypic background of cultivar Floradade were deployed in the study: four inbred lines (Floradade-normal genotype, TOM-559-norA/norA, TOM-613-nor/nor and TOM-614-rin/rin ) and eight hybrids F1(TOM-559 x TOM-613)-nor/norA, F1(FloraDade x TOM-559)-nor+/norA, F1(FloraDade x TOM-613)-nor+/nor, F1(FloraDade x TOM-614)-rin+/rin, F1(TOM-559 x TOM-614)-rin+/rin nor+/norA, F1(TOM-613 x TOM-614)-rin+/rin nor+/nor, F1(TOM-591 x TOM-614)-rin+/rin nor+/norA ogc+/ogc and F1(TOM-589 x TOM-614)-rin+/rin nor+/norA ogc+/ogc hp+/hp). These genotypes were evaluated for total and early yields, fruit firmness at the breaker stage, firmness half life period, and final fruit color. No detectable differences were found among the genotypes, with Floradade with highest yields and rin/rin with the lowest. The presence of ripening mutants, whether associated or not to to color enhancing mutants, reduced early yields. No difference for firmness at the breaker stage was detected among the genotypes tested. The ripening mutant double heterozygous genotypes rin+/rin nor+/norA, rin+/rin nor+/nor, rin+/rin nor+/norA ogc+/ogc and rin+/rin nor+/norA ogc+/ogc hp+/hp increased firmness half life by 7.87 to 9.68 days when compared to the normal genotype Floradade. The deployment of ogc+/ogc hp+/hp along with rin+/rin nor+/norA tended to promote slight improvement (decrease in the hue angle) both in the external color (epidermis) and in the internal color, especially in the placentary gel. Presence of ogc+/ogc hp+/hp in combination with rin+/rin nor+/norA was also effective in improving chroma in the pericarp and placenta. Our results indicate that that deployment of the double heterozygous combination rin+/rin nor+/norA is effective towards improving fruit shelf life, not only with relation to the normal genotype, but also relatively to the single heterozygous genotypes rin+/rin and nor+/norA. Possible deleterious effects of the double combination rin+/rin nor+/norA on external and on internal fruit color are similar to those presented by the single heterozygous genotype rin+/rin (widely deployed in commercial hybrids), and may be atenuated by simultaneous deployment of alelles ogc and hp in the combination rin+/rin nor+/norA ogc+/ogc hp+/hp.