Effects of limited introgressions from Triticum timopheevii Tausch. into the genome of bread wheat (Triticum aestivum L.) on physiological and biochemical traits under normal watering and drought

Alien hybridization in cereals is used for the comparative investigation of the genome structure and evolution, as well as for extracting useful genes from the wild gene pool. The tetraploid species Triticum timopheevii has long been used as a source of genes for resistance to fungal diseases. Line 821 was developed on the genetic background of cultivar Saratovskaya 29 (S29), which is drought-resistant but is very susceptible to diseases and carries large introgressions in 2A and 2B chromosomes and a small introgression in the subtelomeric region of the 5A chromosome. The two genotypes were compared for the parameters associated with the direct and indirect reaction of the photosynthetic apparatus to water stress. In the flag leaves of line 821, an increased transpiration rate and stomatal conductance (1.6 times the value in optimal watering and 1.2 times the value under a water deficit) and, correspondingly, reduced efficiency of water usage were found compared to the initial cultivar. Additionally, the actual effectiveness and electron transport rate of photosystem II, the chlorophyll and carotenoid content, and the total antioxidant capacity were reduced by approximately a factor of three under water stress. Under the same conditions, the activity of lipoxygenase doubled. On the whole, tolerance to a water deficit declined in the line in comparison to the parent cultivar and was accompanied by leaf senescence. Thus, it may be supposed that 2A, 2B, and 5A chromosomes of the drought-tolerant cultivar S29 carry important genetic factors responsible for the reaction to water stress in wheat plants.