Drought, an abiotic stress, considered as one of the factors limiting food resources. The plant responses to adaptive to such a condition are accompanied with changes in the expression pattern of some functional as well as regulatory genes. The MYB proteins include a big family of transcription factors which are highly important in regulating development process and immunizing responses of plants. This research was conducted to evaluate the expression of TaMYB73 transcription factor and catalase and polyphenol peroxidase enzymes activity in bread wheat cultivars (Hamoon, Hirmand, Kavir, Bolani, and Cross Bolani) under drought stress conditions. Factorial experiment was conducted in pot based on a completely randomized block design with three replications. Following 45 days from seed planting (four- leaf stage), drought stress was done at five levels of different irrigation and then the leaves of treated plants were sampled to measure of enzyme activity and gene expression. After RNA extraction and c DNA synthesis, the gene expression pattern was evaluated using Real-time PCR and data analysis was performed via 2^{-ΔΔ ct} method. The results showed that TaMYB73 gene expression level as well as the catalase and polyphenol peroxidase enzymes activities corresponding to the Hirmand cultivar was higher than the other cultivars.

In order to identify loci controlling seedling morpho-physiologic characteristics in 88 bread wheat cultivars, a greenhouse experiment based on simple alpha lattice was conducted under both normal and 120 mM (12 ds/m) salt stress condition of the Faculty of Agriculture, Urmia University in 2020-2021 cropping season. Chlorophyll a, b and carotenoid content, proline, plant fresh and dry weight, plant height and leaf relative water content (RWC), Na⁺, K⁺ and K⁺/Na⁺ concentrations were measured. After genotyping by sequencing with Ion Torrent technology and removal of SNPs with more than 20% of missing data and minor allele frequency less than 5%, a total of 5869 SNP markers were identified. Based on association mapping with the mixed linear model (MLM) method, a total of 25 marker-trait associations were detected under normal conditions. The A and D genomes had the highest and lowest number of significant marker-trait associations (MTAs). Among the studied traits under normal conditions, chlorophyll a had the highest number of MTAs on 1A, 3B, 3D, 5B, 7A chromosomes with eight MTAs. A total of 21 MTAs were identified under salt stress conditions which the genome B and D had the highest and lowest number of MTAs, respectively. Five MTAs were identified for plant fresh weight, which were located on chromosomes 4A and 6B. The results of this study provide valuable information about the loci associated with the studied traits, which can be used in marker assisted selection in wheat breeding programs after confirmation in biparental populations and additional experiments.