Molecular, physiological, and agronomical characterization, in greenhouse and in field conditions, of soybean plants genetically modified with AtGolS2 gene for drought tolerance

Abstract

Water deficit may occur at any stage of crop development, affecting productivity and causing economic losses. In response to drought, raffinose family oligosaccharides (RFOs) are accumulated in plant tissues stabilizing and protecting cell membranes and keeping the vital functions. The enzyme galactinol synthase (GolS, EC 2.4.1.123) catalyzes the first step in the biosynthesis of RFOs. In our study, soybean events overexpressing 35S:AtGolS2 were molecularly, physiological, and agronomical characterized, under drought simulated in greenhouse and in field conditions during the crop season 2014/2015. The conventional soybean cultivar BRS 184 was transformed and five positive events were obtained. Four events transmitted the transgene to further generations and in the events 2Ia1 and 2Ia4, two to four copies of AtGols2 gene were observed. Results in greenhouse showed that the overexpression of AtGolS2 in genetically modified (GM) plants led to increased galactinol transcripts, probably resulting in changes in carbohydrate metabolism. Accumulation of these transcripts that may have acted as osmoprotectors, lead to higher drought tolerance and survival rate of 2Ia4 plants. In addition, in field conditions, higher yield was observed for 2Ia4 plants under irrigated (IRR) and non-irrigated (NIRR) treatments. This result can be due to the increased synthesis of RFOs even under well-watered conditions. This field screening showed promising results for drought tolerance, suggesting that 2Ia4 plants may be useful in a breeding program for the development of drought-tolerant plants. However, additional studies are needed in further crop seasons and other sites to better characterize how these plants may outperform the WT plants under water deficit.