Growth and transpiration of soybean genotypes with AtAREB1 transcription factor for tolerance to water deficit

The objectives of this study were (i) to identify growth and physiological changes in soybean resulting from the insertion of the TF AtAREB1, both in the original 1Ea2939 event and in an improved genotype derived from the cross between 1Ea2939 and the elite cultivar BMX Desafio RR; (ii) to determine the ecophysiological traits contributing to drought tolerance in soybean with the TF AtAREB1, compared to commercial cultivars, using the fraction of transpirable soil water (FTSW) approach; and (iii) to evaluate the field performance of AtAREB1 genotypes in comparison to their parents. Greenhouse experiments were conducted to evaluate leaf transpiration rates, leaf growth, dry matter accumulation, gas exchange, and water use efficiency (WUE) in four commercial cultivars, as well as in the AtAREB1 genotypes 1Ea2939 and BRT18-0280. Additionally, a field experiment was carried out to assess grain yield and water use efficiency in AtAREB1 genotypes. The “AtAREB1” genotypes exhibited reduced daily transpiration rates in both irrigated and dry environments compared to the commercial cultivars. The higher drought tolerance can be attributed to a lower FTSW threshold for leaf transpiration rate, a higher root/shoot ratio, and prolonged survival during drought conditions.The “BRT18-0280” genotype showed a higher yield and water use efficiency under field conditions. This study indicates that soybean with TF AtAREB1 is an alternative to increase soybean tolerance to water deficit in regions where drought is a limiting factor for high yields.