Expression anaysis of WRKY transcription factors in response to drought stress in some Prunus rootstocks

The stone fruit species within the Prunus genus are produced and consumed around the world. These fruit species are perennial plants growing in the same environment for many years and exposed to various abiotic and biotic stresses decreasing the yield and quality. Therefore, different rootstocks are used against different stresses in stone fruit production. Drought stress has become increasingly important due to climate changes caused by global warming in recent years. Plants have developed different mechanisms against drought, and in these mechanisms, transcription factors (TF) regulate the expression of genes that play a role in adaptation or tolerance to drought stress. And among TF families, WRKY constitute the second largest family. In this study, first, the performances of 11 Prunus rootstocks used in production of Prunus species during 30-day drought stress were evaluated. The expression of WRKY genes in response to drought stress showed that 10 out of 15 WRKY genes are induced during drought stress indicating that they play a role in drought stress response in peach plants. Then, two of these genes, WRKY5 and WRKY9, were selected, and their expressions during drought stress were determined in 10 different Prunus rootstocks. Furthermore, sequences of WRKY5 and WRKY9 genes were obtained from different rootstocks and compared with each other to reveal sequence differences. The results show that these WRKY TFs are genetically conserved, and involved in drought stress response in different Prunus rootstocks. Therefore, they may be used for developing new Prunus rootstocks resistant to drought stress.