Defining the roles of PvMDH genes in response to salt stress and detailed characterization of the gene family

Malate dehydrogenase (MDH) genes play a very important role in different metabolic pathways and have been studied in many plant species so far. However the genome-wide study of the MDH family has not yet been carried out in the common bean. For this reason, the MDH family has been characterized in depth at both gene and protein levels and several bioinformatics methods have been used. As a result, 8 MDH genes have been identified and their proteins have been categorized into three main phylogenetic groups. By investigating duplications that play a major role in the development of gene families, two segmental duplication events have been found in the MDH family in common bean. In addition, using available RNAseq data, comparative expression analysis of MDH genes was performed and expression changes in PvMDH-3, 6 and 8 genes were shown under salt stress. In leaf and root tissues of two common bean cultivars (Yakutiye ‘tolerant’ and Zulbiye ‘susceptible’ cv.) demonstrating different responses to salt stress, these genes (PvMDH-3, 6 and 8) were screened with qRT-PCR. These genes showed opposite expression pattern between two common bean cultivars under salt stress conditions and this may explain the role of them in abiotic stress response especially in root tissues. In summary, this work is the first study in which in-silico identification and characterization of PvMDH genes has been examined at gene expression level. The results could therefore provide the basis for future studies of functional characterization of PvMDH genes.