NHC Key Laboratory of Tropical Disease Control, School of Tropical Medicine, Hainan Medical University, Haikou, 571199, China.
Ministry of Education Key Laboratory for Genetics and Germplasm Innovation of Tropical Special Forest Trees and Ornamental Plants, Hainan University, Haikou, 570228, China.
BMC Plant Biol. 2024 Nov 29;24(1):1143. doi: 10.1186/s12870-024-05859-y.
As precipitation patterns are predicted to become more erratic, it's vital to understand how abrupt climate events will affect woody seedlings that develop different hydraulic strategies. We cultivated anisohydric Robinia pseudoacacia L. and isohydric Quercus acutissima Carr. in a greenhouse, and subjected an abrupt precipitation event during a successive drought. Patterns of leaf and root gas exchange, leaf and stem hydraulics, seedlings growth, and non-structural carbohydrate (NSC) patterns were determined.
We found that as an anisohydric species, R. pseudoacacia seedlings adopted a strategy of sacrificing leaves in response to stress, resulting in the lowered photosynthesis and ultimately leading to a decrease in NSC accumulation. In contrast, isohydric Q. acutissima maintained the integrity of leaves by reducing respiratory consumption in response to drought stress, thereby ensured the stability of NSC pool.
R. pseudoacacia exhibited an extravagant strategy with efficient water transport, photosynthetic assimilation, and growth capabilities, but its resistance to embolism was relatively weak, while Q. acutissima adopted a resource-saving strategy with higher hydraulic safety. We also found that Q. acutissima seedlings were prone to allocate carbohydrates to maintain growth, while R. pseudoacacia preferred to sacrifice growth and aboveground NSC limitation only happened when precipitation was subjected after total stomatal closure. We thus believe that hydraulic strategy could define seedlings responses to drought and recovery, and further may adversely affect their re-sprouting capacity after drought stress relief.
由于预计降水模式将变得更加不稳定，了解突发气候事件将如何影响采用不同水力策略的木本幼苗至关重要。我们在温室中培育了耐旱的刺槐（Robinia pseudoacacia L.）和中生的栓皮栎（Quercus acutissima Carr.），并在连续干旱期间经历了一次突发降水事件。测定了叶片和根气体交换、叶片和茎水力、幼苗生长和非结构性碳水化合物（NSC）模式。
我们发现，作为耐旱物种，刺槐幼苗采用了牺牲叶片应对胁迫的策略，导致光合作用降低，最终导致 NSC 积累减少。相比之下，中生的栓皮栎通过减少干旱胁迫下的呼吸消耗来维持叶片的完整性，从而确保 NSC 库的稳定性。
刺槐表现出奢侈的策略，具有高效的水分运输、光合作用同化和生长能力，但对栓塞的抵抗力相对较弱，而栓皮栎则采用了节约资源的策略，具有更高的水力安全性。我们还发现，栓皮栎幼苗更容易分配碳水化合物来维持生长，而刺槐则倾向于牺牲生长，只有在总气孔关闭后再进行降水时才会出现地上 NSC 限制。因此，我们认为水力策略可以定义幼苗对干旱的响应和恢复，进一步可能对其干旱缓解后的再萌芽能力产生不利影响。
