Expression of the W36, P5CS, P5CR, MAPK3, and MAPK6 genes and proline content in bread wheat genotypes under drought stress

In the first research, we evaluated some agronomic traits in 14 bread wheat genotypes (Triticum aestivum) and then selected the most tolerant and sensitive genotypes based on the results of multivariate analysis in two levels of drought stress (moderate and severe). In the second section, the proline content and expression levels of five genes, namely vacuolar-type H+-ATPase subunit E (W36), Delta(1)-pyrroline-5-carboxylate synthase (P5CS), Delta(1)-pyrroline-5-carboxylate reductase (P5CR), mitogen-activated protein kinase 3 and 6 (MAPK3, and MAPK6), were investigated in the tolerant (Backcross and Roshan) and sensitive (Omid and Shirodi) genotypes. The quantitative real-time PCR (qRT-PCR) analysis showed that W36 gene expression increased with the intensification drought stress levels. According to our data, increasing drought stress levels led to increasing expression levels of P5CS and P5CR genes resulting in enhancement of proline content. Under severe drought stress, MAPK3 and MAPK6 genes expression elevated in comparison with the moderate and control conditions. Also, the expression of the evaluated genes in this study along with the content of proline in the most tolerant genotypes was extremely higher than that of the sensitive ones. Therefore, these reactions under drought stress could be regarded as the important reasons for tolerance of drought stress in Roshan and Backcross genotypes in this study. In addition, according to these results, these genes can be drought stress-induced genes and have the potential to be used for the betterment of drought stress tolerance in wheat.