Comparative analysis of combined phosphorus and drought stress-responses in two winter wheat

Phosphorus stress and drought stress are common abiotic stresses for wheat. In this study, two winter wheat varieties "Xindong20" and "Xindong23" were cultured in a hydroponic system using Hoagland nutrient solution and treated with drought stress under conventional (CP: 1.0 mmol/L) and low (LP: 0.05 mmol/L) phosphorus levels. Under drought stress, the root growth was better under LP than under CP. Under LP, root phosphorus content was increased by 94.2% in Xindong20 and decreased by 48.9% in Xindong23 at 3 d after re-watering, compared with those at 0 d under drought stress. However, the potassium (K) content was the highest among the four elements studied and the phosphorus (P) and calcium (Ca) content were reduced in the root of the two varieties. Under CP, the zinc (Zn) content was higher than that under LP in Xindong23. The GeneChip analysis showed that a total of 4,577 and 202 differentially expressed genes (DEGs) were detected from the roots of Xindong20 and Xindong23, respectively. Among them, 89.9% of DEGs were involved in organelles and vesicles in Xindong20, and 69.8% were involved in root anatomical structure, respiratory chain, electron transport chain, ion transport, and enzyme activity in Xindong23. Overall, LP was superior to CP in mitigating drought stress on wheat, and the regulatory genes were also different in the two varieties. Xindong20 had higher drought tolerance for more up-regulated genes involved in the responses compared to Xindong23.