Genetic variation of leaf antioxidants and chlorophyll content in safflower.

Abstract

An efficient antioxidant defense system represented by enzymatic and non-enzymatic forms is important in the control of oxidative stress caused by free radicals and other reactive species. Leaf antioxidant activity and chlorophyll content of 20 safflower (Carthamus tinctoriuos L.) genotypes comprising eight parental and 12 F1 hybrids originated from reciprocal crosses of four parental lines were evaluated in this study. Five leaf antioxidants including ascorbate peroxidase (APX), glutathione reductase (GR), super oxide dismutase (SOD), carotenoids and lipid peroxidastioin (LP) were assessed. Chlorophyll (a, b, a+b) content was also evaluated. Analysis of variances for all traits showed the significant differences among the genotypes (P < 0.05). The highest antioxidant activity was consistently belonged to APX and GR in all genotypes. Cross 22-191× k 21 was superior for GR and APX activity among F1 hybrids. The highest activity of SOD and LP was observed in C4110 genotype. GE-62918 showed the highest content of carotenoids. The highest chl a and chl a+b was related to a F1 hybrid (22-191◊K21). In the majority of F1 hybrids the activity of antioxidant was higher and chlorophyll content was intermediate when compared to those of their parents. Significant differences were observed between reciprocal crosses for the antioxidants with the exception of the GR. This result in turn indicated that the cytoplasmic effects on the antioxidant activity in safflower. There was no significant difference between reciprocal crosses for chlorophyll content with the exception of 22-191◊K21 cross. The heterosis effect for SOD activity was significant (143, 95 and 54.4) in three genotypes related to superior parent and in three genotypes (96.2, 40 and 31) related to mean of parents. Significant heterosis (122.86 and 156.20) was only observed for two genotypes related to mean of parents for Chl a and Chl b contents, respectively.