Dehydration stress tolerance in sesame plants (Sesamum indicum L.) over expressing the Arabidopsis thaliana molybdenum cofactor sulfurase LOS5laba3 gene under greenhouse conditions

In the current work, we cloned the Arabidopsis thaliana LOS5/ABA3 gene (which encodes a molybdenum cofactor sulfurase enzyme required at the final ABA synthesis stage) and transformed it into sesame (Sesamum indicum L.) via Agrobacterium. LOS5 gene insertion and integration into transgenic plants was confirmed via PCR screening of T-0 and T-1 plants. Segregation ratio in T-1 lines were consistent with single gene insertion in 5 out of 6 tested lines; RT-PCR was used to confirm expression in T-1. Under non-stressed conditions, differences in height, node and leaf numbers were observed among transgenic lines, while under severe drought conditions (25% of pot irrigation capacity), transgenic plants showed less reduction in height (26.0-35.5%) compared to azygous (AZ) non-transgenic plants (more than 50% reduction). Increase in total extractable soluble proteins, elevation in proline accumulation, and a reduction in MDA levels were recorded in transgenic lines. Further analysis of enzymes involved in scavenger of reactive oxygen species (ROS) revealed that under non-stressed conditions, ascorbate peroxidase (APX), catalase (CAT), peroxidase (PDX) and superoxide dismutase (SOD) activity levels increased by as much as 25, 23, 210 and 75% respectively, compared to AZ. This trend of result was recorded under stress condition but to less degree. Our results indicate that elevation in drought tolerance was achieved in LOS5-overexpressing sesame lines partially through accumulation of proline, and reduction in cellular membranes oxidative-damage "activation of scavenging enzymes". To our knowledge this is the first report on transformation of useful gene in sesame.