Hormetic effect of gamma irradiation under salt stress condition in Phaseolus vulgaris

Kamile Ulukapi1
Common bean (Phaseolus vulgaris L.) grown around the world and sensitive to stress conditions. Accumulationand degradation of amino acids are informative indicators of plant tolerance. In this study, the vegetative growth andamino acid profiles of two common bean cultivars (Öz Ayse and F16) under salt stress (50, 100, 150, 200 mM NaCl) wereinvestigated to determine the hormetic effect of low-dose gamma rays (10, 20, 30, 40 Gy 60Co). The irradiated matureembryos of seeds were regenerated in vitro using embryo cultures. The effects of gamma rays on vegetative growth andamino acid profile under stress and non-stress conditions differed. In terms of vegetative growth, 10 Gy for 'Öz Ayse'and 20 Gy for 'F16' had hormetic effects and stimulated plant growth under non-stress conditions. Under salt stressconditions, the effect of gamma rays varied according to the severity of the stress. 30 Gy for 'Öz Ayse' and 'F16' at 100mM salt stress had hormetic effects on vegetative growth. The combined effects of salt stress and gamma rays on the amino acid profile are supported by the vegetative growth results of the plants. Amino acid accumulation occurred at 100 mM at 30 Gy for 'Öz Ayse' and 'F16'. The most accumulated amino acids were glutamic acid (127.63 mg kg-1), alanine(173.07 mg kg-1), glutamine (188.96 mg kg-1), proline (124.50 mg kg-1), tyrosine (29.23 mg kg-1) in 'Öz Ayse' and tyrosine(29.88mgkg-1) in 'F16' under stress. This study shows that low-dose gamma application under moderate stress conditions has a hormetic effect, not under severe salt stress.
Keywords: Amino acid, common bean, embryo culture, hormesis, low-dose gamma.
1Akdeniz University, Vocational High School of Technical Sciences, Department of Plant and Animal Production, 07059, Antalya, Turkey.*Corresponding author (kamileonal@akdeniz.edu.tr).