Gene expression and identification of metal ion transport proteins to assess iron (Fe) and zinc (Zn) accumulation in common bean (Phaseolus vulgaris L.)

MTP/CDF carriers, called metal ion transport proteins, act as substrates for the transmission of micronutrients such as zinc (Zn), manganese (Mn), and iron (Fe) to membrane carriers in plants. It also provides to transport of nutrients from the cytoplasm to the extracellular space or organelles. Although the common bean genome sequence has been defined, it has been determined that there is no study in the literature on the characterization of MTP genes and the expression levels of Fe-Zn applications. In this study, genome-wide analysis of the MTP gene family in the common bean genome, expression analysis of PvMTP4, PvMTP5, and PvMTP12 genes under Fe (0 µM, 15 µM, and 30 µM) and Zn (0 µM, 10 µM, and 15 µM) treatments, and the effects of Fe and Zn applications on pod length, pod weight, root weight, iron content, and zinc content were investigated. During this study used four common bean genotypes (EL-29, MŞ-46, BN-16, SV-12) assumed to have high or low Fe and Zn accumulation ability. In the study, nine different PvMTP genes (4, 5, 6, 7, 8, 9, 10, 11, 12) have been defined containing conserved catalytic domains with protein lengths and molecular weights ranging from 369 to 813 amino acids (aa) and 41.35 to 91.05 kDa, respectively. As a result of the phylogenetic analysis, three main clusters containing seven subgroups were formed. Three PvMTP genes were grouped in Zn-CDF, 2 in Zn/Fe CDF, and 4 in Mn-CDF. With this study, the first characterization of the MTP gene family in beans was performed, and the response of three different PvMTP genes in the Zn-CDF group to Fe and Zn applications was revealed. It is thought that the obtained findings will constitute pioneering resources for future research on common bean biofortification studies, plant breeding related to Fe and Zn, understanding and functional characterization of the MTP gene family.