Ionomic and metabolic responses of wheat seedlings to PEG-6000-simulated drought stress under two phosphorus levels

Abstract

Background Wheat (Triticum aestivum L.) is a major food crop worldwide. Low soil phosphorus content and drought are the main constraints on wheat production in Xinjiang, China. Methods In this study, the ionic and metabolic responses of one wheat variety (“Xindong20”) to drought stress simulated by using polyethylene glycol 6000 (PEG-6000) were investigated under low phosphorus (LP) and conventional phosphorus (CP) conditions by analysing wheat mineral elements and metabolites. Besides, due to xanthohumol was the metabolite with the most significant difference in expression detected in “Xindong 20”, two wheat variety “Xindong20 and Xindong 23” were selected to conduct the germination test simultaneously, to further verify the function of xanthohumol in wheat growth. Xanthohumol was mixed with PEG solution (20%) to prepare PEG solutions with different concentrations (0%, 0.1%, 0.5%, and 1%) of xanthohumol. Then wheat grains were soaked in the solutions for 20 hours, followed by a germination test. After 7 days, the indicators including shoot length, max root length, and root number were determined to identify whether the metabolite was beneficial to improve the drought tolerance of wheat. Results The results showed that the root density and volume of wheat in LP treatment were higher than those in CP treatment. The roots underwent programmed cell death both in LP and CP treatments under PEG-6000-simulated drought stress, however, the DNA degradation in root cells in LP treatment was lower than that in CP treatment after rehydration for 3 d. Before drought stress, the malondialdehyde (MDA) content in shoot and the peroxidase (POD) activity in root in LP treatment were significantly higher than those in CP treatment, while the soluble sugar content and chlorophyll content in LP treatment were significantly lower than those in CP treatment. During drought stress, the POD activity maintained at a high level and the soluble sugar content gradually increased in LP treatment. After rehydration, the MDA content still maintained at a high level in LP treatment, the superoxide dismutase (SOD) activity increased, and the contents of soluble sugar and chlorophyll were significantly higher than those in CP treatment. The analysis of mineral elements and metabolites showed that the wheat in CP treatment was more sensitive to drought stress than that in LP treatment. Besides, the effect of drought stress was greater on shoot than on root in CP treatment, while it was opposite in LP treatment. The effect of drought stress on sugar metabolism gradually increased. Germination assays showed that 0.1% exogenous xanthohumol addition could significantly increase the shoot length of the two wheat varieties under drought stress. Conclusion Appropriate low phosphorus supply could increase antioxidant enzyme activity in wheat, and enhance sugar metabolism to regulate osmotic balance, as well as the accumulation of various organic acids to maintain the intracellular ion homeostasis. Therefore, compared to the conventional phosphorus supply level, appropriate low phosphorus supply can significantly improve the drought tolerance of wheat. Additionally, addition of 0.1% exogenous xanthohumol, an important differential expressed metabolite in drought-stressed wheat, could effectively promote wheat shoot growth under drought stress.

The opportunity of using durum wheat landraces to tolerate drought stress: screening morpho-physiological components

“…Under drought stress conditions, plants accumulate other osmotically active substances as sugars ( Sami et al ., 2016 ; Basu et al ., 2016 ; Hussein et al ., 2022 ; Chunyan et al ., 2022 ). Our data showed a substantial increase in this solute correlated with water stress levels as previously reported ( Sedaghat et al ., 2020 ; Adrees et al ., 2020 ).…”

Study of the genetic variability of durum wheat (Triticum durum Desf.) in the face of combined stress: water and heat

“…Under conditions of water and heat stress, plants accumulate other osmotically active substances like sugars ( Basu et al 2016 ; Sami et al 2016 ; Xie et al 2020 ; Chunyan et al 2022 ; Hussein et al 2022 ). Our data showed a substantial increase in this solute correlated with the severity of applied stress, as previously reported ( Adrees et al 2020 ; Sedaghat et al 2020 ).…”