Cloning and quantitative expression analysis of drought-induced genes in soybean

We determined the expression levels of DREB transcription factor (Gmdreb1) and of the genes Gmgols, Gmpip1b, Gmereb, and Gmdefensin in drought-tolerant (MG/BR46-Conquista) and drought-sensitive (BR16) genotypes of soybean, during drought. The trial was carried out in a controlled-environment chamber, set up to provide drought conditions. Sequences of Arabidopsis thaliana DREB-family proteins were used to build a phylogenetic tree through the alignment of the conserved regions near the AP2 domain. We found that Gmdreb1 is similar to Atrap2.1, which is located near the AtDREB1 and AtDREB2 families. The amplified fragment was cloned and sequenced; alignment with the sequence available at Genbank showed total similarity. Expression analysis showed that under drought: a) Gmdreb1 expression increased in leaves and roots of both genotypes and expression level changes occurred that were correlated with the length of the water-deficit period; b) there were increased expression levels of Gmdefensin in roots of MG/BR46; c) expression of Gmgols increased in leaves and roots of the two genotypes; d) Gmpip1b expression generally increased, except in roots of BR16, and e) the same was found for Gmereb, except in roots of MG/BR46.