Screening Diverse Aegilops tauschii for osmotic stress tolerance through physio-biochemical and anatomical characterization

Wheat faces significant challenges due to environmental stresses, particularly to drought, which can severely hinder plant growth especially at germination stage. One of the strategies to improve crops productivity is to explore genetic resources especially wild relatives of crops for osmotic stress tolerance. Hence, an experiment was conducted to screen 31 Aegilops tauschii accessions and two wheat check cultivars under in vitro conditions in completely randomized design (CRD) under polyethylene glycol (PEG 7.5 and 15%) induced osmotic stress. The morpho-anatomical, and physio-biochemical characteristics of the experimental A. tauschii accessions and two wheat check cultivars were investigated. Overall, a decline was observed in the studied physio-biochemical traits including relative water contents (28.2, 54.5%), chlorophyll a (16.9, 31.0%), chlorophyll b (15.2, 26.6%), total chlorophyll (16.3, 29.2%), and carotenoid (13.3, 27.7%) under moderate, and severe osmotic stress, respectively. However, proline contents were positively correlated with increasing concentrations of PEG, showing a rise of 29.3% in moderate and 63.4% in severe osmotic stress. Additionally, the studied morpho-anatomical features were also negatively affected by PEG treatments, including shoot length (6.9, 34.7%), root length (16.9, 21.4%), xylem vessels diameter (9.3, 12.8%), phloem length (5.1, 8.7%) and phloem width (4.7, 7.9%) respectively, The results of the current study revealed that the A. tauschii accessions AT-01, AT-02, AT-05, AT-10, AT-14, AT-15, AT-16, AT-19, AT-23, AT-29, and AT-31were tolerant and outperformed the Pirsabak-2019, which is rainfed cultivar, and therefore these genotypes are recommended for the use in wheat breading program.