Mechanistic Insights into Potassium-Conferred Drought Stress Tolerance in Cultivated and Tibetan Wild Barley: Differential Osmoregulation, Nutrient Retention, Secondary Metabolism and Antioxidative Defense Capacity.

Shafaque Sehar,Muhammad Zeeshan,Paul Holford,Fangbin Cao,Muhammad Faheem Adil,Yizhou Wang,Feibo Wu

doi:10.3390/ijms222313100

Abstract

Keeping the significance of potassium (K) nutrition in focus, this study explores the genotypic responses of two wild Tibetan barley genotypes (drought tolerant XZ5 and drought sensitive XZ54) and one drought tolerant barley cv. Tadmor, under the exposure of polyethylene glycol-induced drought stress. The results revealed that drought and K deprivation attenuated overall plant growth in all the tested genotypes; however, XZ5 was least affected due to its ability to retain K in its tissues which could be attributed to the smallest reductions of photosynthetic parameters, relative chlorophyll contents and the lowest Na+/K+ ratios in all treatments. Our results also indicate that higher H+/K+-ATPase activity (enhancement of 1.6 and 1.3-fold for shoot; 1.4 and 2.5-fold for root), higher shoot K+ (2 and 2.3-fold) and Ca2+ content (1.5 and 1.7-fold), better maintenance of turgor pressure by osmolyte accumulation and enhanced antioxidative performance to scavenge ROS, ultimately suppress lipid peroxidation (in shoots: 4% and 35%; in roots 4% and 20% less) and bestow higher tolerance to XZ5 against drought stress in comparison with Tadmor and XZ54, respectively. Conclusively, this study adds further evidence to support the concept that Tibetan wild barley genotypes that utilize K efficiently could serve as a valuable genetic resource for the provision of genes for improved K metabolism in addition to those for combating drought stress, thereby enabling the development of elite barley lines better tolerant of abiotic stresses.

Highlights

Due to global warming and subsequent climatic abnormalities, plants have evolved to live in environments where they are often exposed to a wide array of stresses such as drought, salinity, waterlogging and extreme temperatures [1,2]
(+K+D), the effects of Polyethylene glycol 6000 (PEG)-induced drought were alleviated to a greater extent in XZ5 (14%, 19% and 16% improvement for shoot heights (SH), root lengths (RL) and SDW, respectively), followed by Tadmor
No significant difference in shoot biomass was observed in XZ54 between +K+D and –K+D, a recovery rate of 6%, 10% and 14% was recorded for RDW, SH and RL, respectively

Summary

Introduction

Due to global warming and subsequent climatic abnormalities, plants have evolved to live in environments where they are often exposed to a wide array of stresses such as drought, salinity, waterlogging and extreme temperatures [1,2]. Drought stress, in particular, causes multidimensional deleterious effects on plant growth, development and productivity. Despite a large number of studies, our understanding of the mechanisms of drought tolerance in barley is still not comprehensive due to the complexity of interactions involved in the physio-biochemical and molecular processes [6]. One of the most cost-effective solutions for sustainable production in water-limiting areas is genetic improvement for higher drought tolerance that could be achieved by understanding the underlying mechanism and identifying the associated genes

Methods

Results

Discussion

Conclusion