Study of CaDreb2c and CaDreb2h Gene Sequences and Expression in Chickpea (Cicer arietinum L.) Cultivars Growing in Northern Kazakhstan under Drought

Drought poses a significant challenge to plant growth and productivity, particularly in arid regions like northern Kazakhstan. Dehydration-responsive element-binding (DREB) transcription factors play an important role in plant response to drought and other abiotic stresses. In Arabidopsis thaliana, the DREB subfamily consists of six groups, designated DREB1 to DREB6. Among these, DREB2 is primarily associated with drought and salinity tolerance. In the chickpea genome, two DREB genes, CaDREB2c and CaDREB2h, have been identified, exhibiting high sequence similarity to Arabidopsis DREB2 genes. We investigated the nucleotide sequences of CaDREB2c and CaDREB2h genes in several chickpea cultivars commonly grown in northern Kazakhstan. Interestingly, the CaDREB2h gene sequence was identical across all varieties and corresponded to the sequence deposited in the GenBank. However, the CaDREB2c gene sequence exhibited variations among the studied varieties, categorized into three groups: the first group (I), comprising 20 cultivars, contained a CaDREB2c gene sequence identical to the GenBank (Indian cultivar CDC Frontier). The second group (II), consisting of 4 cultivars, had a single synonymous substitution (T to C) compared to the deposited CaDREB2c gene sequence. The third group, encompassing 5 cultivars, displayed one synonymous substitution (C to T) and two non-synonymous substitutions (G to T and G to A). Furthermore, we assessed the gene expression patterns of CaDREB2c and CaDREB2h in different chickpea varieties under drought conditions. Chickpea cultivars 8 (III), 37 (I), 6 (III), and 43 (I) exhibited the highest drought resistance. Our analysis revealed a strong positive correlation between drought resistance and CaDREB2h gene expression under drought stress. Our findings suggest that the chickpea's adaptive responses to water deprivation are associated with changes in CaDREB2 gene expression. To further elucidate the mechanisms underlying drought tolerance, we propose future research directions that will delve into the molecular interactions and downstream targets of CaDREB2 genes.