Improved salt-tolerance of transgenic soybean by stable over-expression of AhBADH gene from Atriplex hortensis

Abstract

An effective strategy for increasing the productivity of major crops under salt stress conditions is the development of transgenics that harbor genes responsible for salinity tolerance. Betaine aldehyde dehydrogenase (BADH) is a key enzyme involved in the biosynthesis of the osmoprotectant, glycine betaine (GB), and osmotic balance in plants, and several plants transformed with BADH have shown significant improvements in salt and drought tolerance. However, very few field-tested transgenic cultivars have been reported, as most of the transgenic studies are limited to laboratory or green house experiments. In this study, we demonstrated through field experiments that BADHfrom Atriplex hortensis (AhBADH) confers salt tolerance when transformed into soybean (Glycine max L.). AhBADH was successfully introduced into soybean by Agrobacterium mediated transformation. A total of 256 transgenic plants were obtained, out of which 47 lines showed significant enhancement of salt tolerance compared to non-transgenic control plants. Molecular analyses of the transgenic line TL7 with the highest salt tolerance exhibited stable inheritance and expression of AhBADH in progenies with a single copy insertion. TL7 exhibited stable enhanced salt tolerance and improved agronomic traits when subjected to 300mM NaCl treatment. Currently, the transgenic line TL7 with stable enhanced salt tolerance, which has been cleared for environmental release, is under biosafety assessment. TL7 stably expressing AhBADH could then be applied in commercial breeding experiments in order to genetically improve salt tolerance in soybean.