Análises bioquímica e genética dos teores de flavonoides e atividade antioxidante em alface

Abstract

Vegetables are rich natural sources of antioxidants. Among the leafy vegetables, lettuce (Lactuca sativa L.) is an important source of some of these phytonutrients beneficial to human health, being widely consumed and showing great economic relevance. Thus, techniques can be used in genetic improvement aiming to improve the nutritional and functional quality of lettuce cultivars. This study aimed to estimate genetic parameters for the content of total flavonoids (TF) and for antioxidant activity (AA) in lettuce populations, obtained from the cross between ‘Darkland’ and ‘Red Star’, two contrasting cultivars in terms of leaf color (green and red, respectively). More than 330 plants, between parents, F1 and F2, were evaluated. TF was determined by spectrophotometry, as well as AA, using DPPH• e ABTS•+ radical scavenging methods. ‘Red Star’ plants presented higher averages than those presented by ‘Darkland’ for the analyzed characteristics, proving that contrasting parents were chosen. The TF was higher in red lettuce compared to green lettuce. The estimated value for heritability in the broad sense was relatively high for TF (82.4 %) and AA DPPH method (52.73 %) and average for AA ABTS method (33.70 %,). The average degree of dominance in both cases showed parcial dominance in order to reduce the values of the evaluated characteristics, but with values ranging from 0.35 to 0.64, indicating the occurrence of additive effects. The phenotypic correlation coefficient between TF and DPPH radical inhibiting capacity was relatively high, presenting a value of 0.64 and slightly lower, with a value of 0.59 for inhibiting the ABTS radical. Relatively high heritability in the broad sense values, associated with the presence of additive effects, indicate the possibility of success in the selection of new superior genotypes for the characteristics of total flavonoid content and antioxidant activity in future generations. The obtaining of new plants with greater antioxidant capacity can be done by indirect selection of plants with a higher content of flavonoids.