Heat Priming During Early Reproductive Stages Enhances Thermo-Tolerance to Post-anthesis Heat Stress via Improving Photosynthesis and Plant Productivity in Winter Wheat (Triticum aestivum L.).

Yonghui Fan,Tingbo Dai,Chuanxi Ma,Xiao Han,Suyu Jiang,Shangyu Ma,Dongguo Jiang,Zhenglai Huang,Wenjing Zhang,Muhammad Abid

doi:10.3389/fpls.2018.00805

Yonghui Fan, Tingbo Dai + Show 8 more

Open Access

https://doi.org/10.3389/fpls.2018.00805

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Abstract

Heat stress during grain filling substantially decreases wheat productivity; thus, to ensure food security, heat tolerance in wheat needs to be developed. In this study, we evaluated the effect of heat priming applied during the stem-elongation stage, booting and anthesis, followed by 5 days of severe heat stress (a 7.86°C rise in temperature) during the grain-filling stage on physiological activities and grain yield of winter wheat in pot experiments during the 2015-2017 growing seasons using the winter wheat cultivars Yangmai 18 (a vernal type) and Yannong 19 (a facultative type). Compared with the damage observed in non-primed plants, heat priming during the stem-elongation stage and booting significantly prevented the grain-yield damage caused by heat stress during grain filling. Heat-primed plants displayed higher sucrose contents and sucrose-phosphate activity in leaves and greater above-ground dry matter than non-primed plants. Priming during stem elongation and booting led to increased photosynthetic capacity, stomatal conductance and chlorophyll contents in comparison with non-priming. Improved tolerance to heat stress due to the enhanced activities of antioxidant enzymes superoxide dismutase and peroxidase and reductions in reactive oxygen species and malondialdehyde production was observed in primed plants compared with non-primed plants of both cultivars. The positive effect of heat priming on the response to heat stress during grain filling was more pronounced in plants primed at the booting stage than in those primed at the stem-elongation or anthesis stage. Moreover, the vernal-type Yangmai 18 benefited more from heat priming than did Yannong 19, as evidenced by its higher productivity. We conclude that heat priming during early reproductive-stage growth can improve post-anthesis heat tolerance in winter wheat.

Highlights

Atmospheric temperatures have increased since the beginning of the 21st century and are predicted to continue increasing, with the global mean air temperature predicted to increase by approximately 1.0–1.7◦C by 2050 (Intergovernmental Panel on Climate Change [IPCC], 2014)
These results indicate that compared with the damage observed in non-primed plants, the grain-yield damage in PSH and PBH caused by heat stress during grain filling was alleviated via increases in the 1000-kernel weight
The present study showed that heat-primed wheat plants displayed a positive response to subsequent high temperature stress that effectively maintained growth and alleviated the damage associated with post-anthesis heat stress

Summary

Introduction

Atmospheric temperatures have increased since the beginning of the 21st century and are predicted to continue increasing, with the global mean air temperature predicted to increase by approximately 1.0–1.7◦C by 2050 (Intergovernmental Panel on Climate Change [IPCC], 2014). The response of plants to high temperature events at different growth stages may have important implications for the development of stress tolerance in crops. Heat stress severely affects plant growth and development and is classified as a major abiotic stressor for numerous crops (Moriondo et al, 2011). Wheat (Triticum aestivum L.) is a widely grown cereal crop that provides food for more than 35% of the global population. The productivity of wheat is severely affected by heat stress (Lobell et al, 2012). Average optimal temperatures for wheat growth range from 17 to 23◦C (Porter and Gawith, 2015), and when the temperature exceeds this range, the plant is considered to be under heat stress, a condition that may cause irreversible damage to crop growth and development. Heat stress can affect wheat growth and productivity at all stages of growth, and if heat stress occurs during the reproductive phase, substantial yield losses are incurred because of the direct effect of heat stress on grain number and mass (Talukder et al, 2014)

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