Coordination between non-structure carbohydrates and hydraulic function under different drought duration, intensity, and post-drought recovery

Abstract

The maintenance of non-structural carbohydrates (NSCs) and hydraulic function during drought and post-drought recovery is crucial for tree survival, but previous studies lack systematic investigation of their relationship under different drought conditions. We exposed seedlings to varying degrees of drought intensity for three years, followed by short-term, high-intensity drought and re-irrigation, to explore the coordination between NSCs and hydraulic function. We found that long-duration drought reduced native embolism in all organs, and NSCs were consumed in trunks and branches in response to drought. In contrast, total soluble sugar and starch concentrations in roots under severe drought stress increased by 33.90 % and 24.97 %, respectively, in order to survive and adapt to the drought environment. When short-term and high-intensity drought caused hydraulic dysfunction, plants accumulated soluble sugars, including glucose, sucrose, and maltose, mainly driven by starch depletion. Meanwhile, drought-adapted plants had higher embolism resistance at the cost of consuming NSCs. After re-irrigation, drought-adapted plants maintain lower carbon consumption and improve carbon reserves in their roots to cope with future drought conditions. In summary, long-term drought treatment improves plant survival under extreme drought stress. This study systematically illustrates the long-term drought legacy effects on short-term drought and re-irrigation responses.