Interaction of the mutant genes B, og ^c , hp and t in the coloring of tomato fruit

Abstract

The aim of this study was to assess the effect of the mutant genes B, og ^c, hp, and t on the fruit color of tomato genotypes. Two tomato lines (TOM-498 and TOM-499) with BB genotype composition (high β-carotene homozygous) were used in hybrid combinations with 7 tomato lines with different genotype compositions in loci og ^c, hp, or t—Floradade, TOM-596, TOM-544, NC-8276, NC-2Y, Florida 7775, and Florida 7781. A randomized complete block design with 24 treatments and four replications was used. Both external and internal fruit color were assessed with a Minolta CR-400 colorimeter in the CIE L*, a* and b* mode. Hue and chroma readings were taken at four different points (epidermis, pericarp, placenta, and columella) of the fruit. For high β-carotene heterozygous hybrids B ⁺ /B, hue angle indicated an orange color (since these hybrids did not come to equal the genotypes of normal coloring, red), even when genes promoting lycopene synthesis (og ^c, hp) were deployed as heterozygous genotypes. Fruit of high β-carotene heterozygous hybrids, without t, og ^c, or hp, had chroma values similar to fruit of homozygous high β-carotene lines. The use of the og ^c allele in heterozygosity led to higher chroma values in high β-carotene heterozygous genotypes in relation to the values found in high β-carotene heterozygous genotypes not bearing the og ^c gene. The og ^c homozygous lines had hue values that did not differ from those in normal genotypes in the epidermis and pericarp, but showed a significant shift towards red in the placenta and in the columella.