Investigation of miRNA responses against heavy metal stress in some domestic wheat varieties

In this study, it was aimed to determine the Cd accumulation potential of two different wheat cultivars (Kutluk-94 and Kunduru-1149) exposed to cadmium stress and determine the changes in the expression levels of 3 different miRNAs miR159, miR171 and miR395 which are known to be involved in heavy metal stress. Kutluk-94 and Kunduru-1149 seeds were germinated in petri dishes containing distilled water and then seedlings were treated in 100, 200 and 300 µM CdCl2 solution for one week. The amount of Cd in wheat root and leaf samples was measured in the ICP-OES device using the wet ashing method. The amount of Cd accumulated in the leaves and roots of both Kutluk-94 and Kunduru-1149 cultivars was found to be statistically significant when compared with the control group. While there was no significant difference in the amount of Cd accumulated in Kutluk-94 and Kunduru-1149 leaves, there was a significant difference in all concentrations in the roots (p<0.05). More Cd accumulation was detected in the roots of Kunduru-1149 cultivar. miRNA expression levels were determined by RT-PCR method. Expressions of heavy metal stress associated miRNAs miR159, miR171 and miR395 varied between cultivars at increasing Cd doses. In Kunduru-1149, miR159 expression was up-regulated in the root, while it was down-regulated in the leaf except the 100 µM CdCl2 concentration. In Kutluk-94, the expression of miR159 was up-regulated in both leaves and roots. It was observed that miR171 was up-regulated in Kutluk-94 leaves and roots at a concentration of 100 µM and down-regulated at a concentration of 200 and 300 µM. The expression of miR171 was down-regulated in the roots and leaves of Cd-treated Kunduru-1149 cultivar. Finally, miR395 was observed to be down-regulated at 100 µM CdCl2 concentration and up-regulated at 200 and 300 µM concentrations in Kutluk-94 leaves. In Kutluk-94 roots, miR395 was up-regulated at all concentrations. It was observed that miR395 was down-regulated at all concentrations in the leaves of Kunduru-1149, while it was down-regulated at 100 µM CdCl2 concentration in the roots, while it was up-regulated at 200 and 300 µM concentrations. Although there have been studies on miRNAs responsible for heavy metal stress in wheat, no such study has been found on domestic wheat varieties. The information obtained from the study is important in terms of guiding future studies on this subject.