Detection of Drought Tolerant Genes in some Apple Rootstocks Seedlings in Syria

This investigation was conducted to detect the presence of three genes associated with drought tolerance within seedling apple rootstocks derived from five apple genotypes, including Syrian apple cultivars. Polymerase chain reaction (PCR) results showed that the amplicon for MdPepPro (a cyclophilin) was found in all studied genotypes and their progenies except for one plant in genotype B. This was followed by the amplicon for an apple heat shock protein gene (MdHSP18), while amplicons of MdDhn1 (Dehydrin1) were detected in fewer of the progenies of the studied genotypes. On the other hand, plants derived from a local apple cultivar Sukari 2 (S2) and genotype A were distinguished by a high number of plants amplifying all three genes, while the genotype B plants had the lowest number of individuals amplifying these genes, in particular MdDhn1 and MdHSP18, compared to the other genotypes. Phenotypic data showed a significant decrease in leaf number in response to deficit irrigation treatment in genotype B. Consequently, this study provides a rapid method for screening apple genotypes for potential drought tolerance and provides initial results for selecting desired genotypes for a further study. Future studies documenting expression of these genes under deficit water will provide additional information towards identifying apple rootstocks with better drought tolerance.