Genome-wide identification of DGK (Diacylglycerol kinase) genes in common bean and association of gene expression levels with abiotic stress factors

Diacylglycerol kinases (DGKs) are enzymes that play an important role in abiotic and biotic stress responses in plants by converting diacylglycerol to phosphatidic acid. Although the genome sequence was determined in common bean, it was determined that there is no study in the literature about the characterization of DGK genes and their expression levels in abiotic stress factors. In this study, genome-wide analysis of DGK gene family in common bean genome, expression profiles under salt stress, phenotyping of local common bean genotypes against cold stress, and expression levels of DGK genes under cold stress in genotypes determined by phenotyping were performed. The 6 DGK genes (PvDGK1;2;3;5a;5b;6) containing conserved catalytic domains with protein lengths and molecular weights ranging from 423 to 727 amino acids (aa) and 47,31 to 81,09 kDa were identified, respectively. Phylogenetic analyses grouped PvDGK genes into three clusters; cluster I, cluster II, and cluster III which had two, one, and three genes, respectively. qRT-PCR analysis was performed in root, stem, leaf, flower and pod tissues under non-stress conditions, in root and leaf tissue (0, 6, 12 and 24 hours) under salt stress condition (150 mM), and in leaf tissue (0, 6, 12 and 24 hours) under cold stress condition (4 ºC). Fv/Fm, PIabs, SPAD, NES, L, a, b, chroma, Hue and visual evaluation criteria were used for phenotyping local common bean genotypes against cold stresses (0 ºC and 5 ºC). It was determined that there were significant variations in cold stress among the genotypes, and the 3 most sensitive and most tolerant common bean genotypes were included in the gene expression study. The characterization of the DGK gene family in common bean was performed for the first time and its importance in the abiotic stress response was revealed. The obtained findings herein will guide future studies on the understanding and functional characterization of the DGK gene family and the breeding studies to be carried out on cold stress near future.