Effect of heat stress on lipid peroxidation and antioxidant enzymes in mung bean (<i>Vigna radiata</i> L) seedlings

Abstract

The aim of this research was to estimate the effects of heat stress on lipid peroxidation and antioxidant enzymes in seedlings of four mung bean genotypes (NM 19-19, NM 20-21, NM 121-123 and NCM 89). Sterilized seeds were grown in petri dishes at optimum temperature (30°C) for 24 h, exposed to 50°C for 2 h (lethal temperature) as well as pretreated to 40°C for 1 h prior to 50°C for 2 h. Changes in malondialdehyde (MDA) content which is an indicator of lipid peroxidation and the activity of guaiacol peroxidase (POD), ascorbate peroxidase (APX), superoxide (SOD) and catalase (CAT) were measured. The results showed that the growth in lethal temperature was extremely poor which improved when pretreatment of 40°C was applied before 50°C. The content of MDA in seedlings treated with lethal temperature was highest at any harvest, which reduced when seedlings were pretreated with 40°C prior to lethal stress. Variable response of antioxidant enzymes activity amongst different genotypes was observed. POD and SOD activities increased under stress in all genotypes except in NM 20-21, APX activity also increased under heat stress in all genotypes. However, the activity of CAT showed reduction under stress for NM 19-19 and NM 121-123 but increase in NM 20-21 and NCM 89. Low MDA content and increased antioxidant enzymes under heat stress were observed in NM 19-19, indicating that it was most thermotolerant genotype. However, high MDA content with decreased activity of antioxidant enzymes were detected in NM 20-21 which could be suggested a least thermotolerant genotype

Keywords: Antioxidant enzymes, lethal temperature, mung bean, malandialdehyde, lipid peroxidation

African Journal of Biotechnology Vol. 12(21), pp. 3196-3203