Department of Botany and Plant Sciences, University of California, 2150 Batchelor Hall, Riverside, CA, 92521, USA.
Evolution, Ecology and Organismal Biology Graduate Program, Department of Biology, University of California, Riverside, CA, 92521, USA.
New Phytol. 2017 Dec;216(4):1119-1129. doi: 10.1111/nph.14737. Epub 2017 Aug 21.
Coordination between stem photosynthesis and hydraulics in green-stemmed desert plants is important for understanding the physiology of stem photosynthesis and possible drought responses. Plants with photosynthetic stems have extra carbon gain that can help cope with the detrimental effects of drought. We studied photosynthetic, hydraulic and functional traits of 11 plant species with photosynthetic stems from three California desert locations. We compared relationships among traits between wet and dry seasons to test the effect of seasonality on these relationships. Finally, we compared stem trait relationships with analogous relationships in the leaf economics spectrum. We found that photosynthetic and hydraulic traits are coordinated in photosynthetic stems. The slope or intercept of all trait relationships was mediated by seasonality. The relationship between mass-based stem photosynthetic CO assimilation rate (A ) and specific stem area (SSA; stem surface area to dry mass ratio) was statistically indistinguishable from the leaf economics spectrum. Our results indicate that photosynthetic stems behave like leaves in the coordination of multiple traits related to carbon gain, water movement and water loss. Because of the similarity of the stem A -SSA relationship to the leaf A -specific leaf area relationship, we suggest the existence of a photosynthetic stem economic spectrum.
茎光合作用与绿色茎沙漠植物水力之间的协调对于理解茎光合作用的生理学和可能的干旱响应非常重要。具有光合作用茎的植物具有额外的碳增益，可以帮助应对干旱的不利影响。我们研究了来自加利福尼亚三个沙漠地点的 11 种具有光合作用茎的植物的光合作用、水力和功能特性。我们比较了干湿季节之间的性状关系，以检验季节性对这些关系的影响。最后，我们比较了茎性状与叶片经济谱中的类似关系。我们发现光合作用茎中的光合作用和水力性状是协调的。所有性状关系的斜率或截距都受到季节性的影响。基于质量的茎光合作用 CO 同化率（A ）与比茎面积（SSA；茎表面积与干质量比）之间的关系在统计学上与叶片经济谱没有区别。我们的结果表明，光合作用茎在与碳增益、水分运动和水分损失相关的多种性状的协调方面表现得与叶片相似。由于茎 A-SSA 关系与叶 A-比叶面积关系的相似性，我们建议存在光合作用茎经济谱。
