Identification of Stress Responsive Genes by Using Molecular Markers to Develop Tolerance in Wheat

Global climate change, which is rising steeply in the world today, has caused further increases in the influence of abiotic stress factors. Abiotic stresses such as drought, high salinity, and high temperatures are common detrimental environmental circumstances that extremely influence growth, cultivation, and productivity worldwide. Traditionally, the varietal selection is based on morphological feature; hence, polygenic characters were very difficult to analyze, and thus such constraints can be overcome by using molecular marker-assisted selection (MAS). As markers are currently available for relatively few traits, MAS must be integrated with the ongoing conventional breeding to maximize its impact. Molecular markers are useful tools to determine the variation in the DNA sequence and eventually the regions of DNA or the genes controlling the qualitative and/or quantitative traits of agronomic significance. The aim of the presented research was to detect the genes and gene loci responsible for the tolerance to salt stress, drought, and high temperatures in wheat using various molecular markers. Wheat genotypes with contrasting stress tolerance, architectonics, productivity, and other physiological traits kept in the gene fund of the Research Institute of Crop Husbandry were used as research objects. Plants were cultivated in the Absheron experimental base under natural conditions (Baku, Azerbaijan). Salt tolerance potential of wheat genotypes was examined genetically based on PCR analysis using various molecular markers associated with salt tolerance. According to the results of the molecular analysis performed with RAPD (OPZ 09) markers linked with salt tolerance, expected 590 bp DNA fragments were amplified in 39% of bread wheat and 27% of durum wheat genotypes. At the same time, salt tolerance gene Nax1 was examined with gwm312 primer in durum wheat genotypes. An expected 200 bp amplicon indicating the existence of this gene in the Barakatli 95, Garabag, Shiraslan 23, Sharg, and Gyrmyzy bugda genotypes was successfully amplified. This amplicon was also synthesized in Barakatli 95, Garabag, Shiraslan 23, and Gyrmyzy bugda genotypes using wmc170 primer linked to salt tolerance locus in durum wheat genotypes. The study of physiological senescence of the flag leaf playing the pivotal role in the uptake of solar energy and stipulating plant productivity in wheat is very important for providing high productivity under stress. Therefore, using RAPD OPH13 marker, the existence of a gene locus linked to the physiological life-span of flag leaf was examined in wheat genotypes under drought stress. Based on the analysis of electrophoretic profiles of PCR results, expected 450 bp fragments were synthesized in 30 wheat genotypes. This result confirms the existence of a gene locus providing the physiological youth of flag leaf, which is considered as the drought tolerance indicator in these genotypes. The existence of the studied locus was not confirmed in 19% of the genotypes. Tolerance to heat stress is a complex phenomenon and controlled by multiple genes imparting a number of physiological and biochemical changes. To differentiate the heat-tolerant and heat-susceptible genotypes of wheat, a heat shock protein (HSP16.9) was taken as a target gene, and domestic genotypes were examined using allele-specific PCR primers. The obtained results can be used in wheat breeding programs for developing wheat varieties tolerant to stresses.