Controle genético dos teores de clorofila e carotenoides em folhas de alface

Abstract

Lettuce is the most consumed hardwood species worldwide and with a great importance functional. The chlorophylls are the most abundant natural pigments present in the plants. The Carotenoids, together with vitamins, are the most investigated substances such as antioxidants. The objective of this study was to determine the genetic control of chlorophyll and carotene content in lettuce leaves (Lactuca sativa L.). It was evaluated both parents besides the F1, F2 and F2:3 generations. Genetic parameters, media components and variance were estimated to determine the type of inheritance involved in the expression of the characteristic chlorophyll and carotenoid content. Hypothesis of monogenic inheritance were tested associated or not with minor polygenic effects by maximum likelihood procedure. The differences between the mean values for total chlorophyll content ranging from 1.1224 mg.g-1 (P1) to 3.3302 mg.g-1 (P2). For carotenoids, the values range from 0.35 mg.g-1 (P1) to 1.34 mg.g-1 (P2). There is a high correlation between the chlorophyll and carotenoid contents, and so the chlorophyll content can be used as surrogate indicators of the carotenoid content. High heritability values were found for total chlorophyll (80%) and carotene (84%). Moreover, the estimate of GMD indicates an incomplete dominance. Of the 27 families evaluated, 6 were characterized as homozygous for low-chlorophyll, 8 were homozygous for high-grade and 13 were segregating. For carotene, 10 were characterized as homozygous down content, 8 as homozygous for high content and 9 segregating. According to the inheritance study, the test revealed that the chlorophyll and carotenoid content is controlled by a gene with additive and dominance effect and by polygenes with less effect.