Assessment of drought stress responsive genes expression profiiles and proline accumulation in a diverse set of grapevine rootstocks

In order to study plant responses to drought stress, it is important to have markers for such responses. This issue has been a challenge for decades and numerous traits have been used for this purpose. In the current study, the influence of drought stress on proline biosynthesis, leaf water potential, and also gene expression levels of 10 genes probably involved in drought stress response regulation pathways were investigated. Also, all experiments were performed in both root and leaf tissues of studied rootstocks to investigate the response of plant tissues which is more suitable for the assessment of possible markers. As a result of the study, the highest percentage of proline increase in leaf and root tissues was mostly observed in susceptible rootstocks. The leaf water potential (-MPa) measurements showed the most decrease in leaf water potential values in highly tolerant rootstocks, so the maximum differences between control and drought stress treated plants were determined in SO4, 140Ru, 1045, and 44-53M rootstocks, respectively. Gene expression levels of HAT5, RAP2-4, WRKY23, GRP, GDH, PRP2, GAS2, PD2, STPK, and GD1 genes were described in 18 different grapevine rootstocks and it was concluded that the root samples indicating more significant gene expression changes, could be more informative than leaf samples.