{Reference Type}: Journal Article {Title}: Biochemical and Ultrastructural Changes in Wheat Plants during Drought Stress. {Author}: Aliyeva DR;Gurbanova UA;Rzayev FH;Gasimov EK;Huseynova IM; {Journal}: Biochemistry (Mosc) {Volume}: 88 {Issue}: 11 {Year}: 2023 Nov {Factor}: 2.824 {DOI}: 10.1134/S0006297923110226 {Abstract}: Drought severely slows down plant growth, decreases crop yield, and affects various physiological processes in plants. We examined four local bread wheat cultivars with different drought tolerance (drought-tolerant Zirva 85 and Murov 2 and drought-sensitive Aran and Gyzyl bughda cultivars). Leaves from seedlings of drought-tolerant plants demonstrated higher activity of antioxidant enzymes and lower levels of malondialdehyde and hydrogen peroxide. The content of soluble proteins in drought-exposed increased, possibly due to the stress-induced activation of gene expression and protein synthesis. Drought-exposed Zirva 85 plants exhibited an elevated activity of nitrogen and carbon metabolism enzymes. Ultrastructural analysis by transmission electron microscopy showed drought-induced damage to mesophyll cells and chloroplast membranes, although it was manifested less in the drought-tolerant cultivars. Comparative analysis of the activity of metabolic and antioxidant enzymes, as well as observed ultrastructural changes in drought-exposed plants revealed that the response to drought of seedlings was more pronounced in drought-tolerant cultivars. These findings can be used in further studies of drought stress in wheat plants under natural conditions.