Genes encoding for tocopherol pathway and antioxidant enzymes induced by γ-irradiation for improvement of seed quality in soybean (Glycine max)

Abstract

Aim: The present investigation was aimed to determine the effect of gamma radiation on genes encoding for tocopherol pathway and antioxidant enzymes in two contrasting soybean genotypes seedlings. Methodology: Seeds from two contrasting soybean genotypes (Bragg and DS-74) were exposed to two different doses of gamma irradiation (0.5 and 1.0 kGy), allowed to germinate and RNA was extracted for cDNA synthesis from 3-days-old soybean seedlings. Expression level of tocopherol pathway and antioxidant enzymes genes was carried out using real time PCR. Seed vigour and moisture contents in seeds of both the soybean genotypes were also analysed. Results: Genes encoding tocopherol biosynthesis and redox enzymes showed higher expression upon 0.5 kGy seed irradiation [3.01 and 3.5 fold for SOD and APXandγ-TMT and MPBQ-MT genes (2.87 and 4.21 fold respectively) in Bragg soybean seedlings] as compared at 1.0 kGy dose of gamma irradiation. The moisture content in control and irradiated soybean seed samples ranged from 8.1 to 15.2 % with DS-74 control seeds showing highest moisture content (15.2%) and Bragg seeds (0.5 kGyirradiated) with lowest moisture content (8.1%). 0.5 kGy irradiated Bragg seeds showed highest seed vigour in the form seed germination (72.25 %) and seedling emergence (61.12%). Interpretation: The result showed that 0.5 KGy of γ- irradiation of soybean seeds were more effective in improving the seed quality by enhancing gene expression of tocopherol pathway and antioxidant enzymes. Key words: Antioxidants, Gamma irradiation, Gene expression, Seed vigour, Soybean