Stewart Jared J, Polutchko Stephanie K, Adams William W, Cohu Christopher M, Wenzl Coleman A, Demmig-Adams Barbara
Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, 80309-0334, USA.
Physiol Plant. 2017 May;160(1):98-110. doi: 10.1111/ppl.12543. Epub 2017 Mar 2.
This study addressed whether the winter annual Arabidopsis thaliana can adjust foliar phloem and xylem anatomy both differentially and in parallel. In plants acclimated to hot vs cool temperature, foliar minor vein xylem-to-phloem ratio was greater, whereas xylem and phloem responded concomitantly to growth light intensity. Across all growth conditions, xylem anatomy correlated with transpiration rate, while phloem anatomy correlated with photosynthetic capacity for two plant lines (wild-type Col-0 and tocopherol-deficient vte1 mutant) irrespective of tocopherol status. A high foliar vein density (VD) was associated with greater numbers and cross-sectional areas of both xylem and phloem cells per vein as well as higher rates of both photosynthesis and transpiration under high vs low light intensities. Under hot vs cool temperature, high foliar VD was associated with a higher xylem-to-phloem ratio and greater relative rates of transpiration to photosynthesis. Tocopherol status affected development of foliar vasculature as dependent on growth environment. The most notable impact of tocopherol deficiency was seen under hot growth temperature, where the vte1 mutant exhibited greater numbers of tracheary elements (TEs) per vein, a greater ratio of TEs to sieve elements, with smaller individual sizes of TEs, and resulting similar total areas of TEs per vein and transpiration rates compared with Col-0 wild-type. These findings illustrate the plasticity of foliar vascular anatomy acclimation to growth environment resulting from independent adjustments of the vasculature's components.
本研究探讨了冬季一年生植物拟南芥是否能够分别且同时调节叶片韧皮部和木质部的解剖结构。在适应高温和低温的植物中，叶片小叶脉木质部与韧皮部的比例更大，而木质部和韧皮部对生长光强的反应是同步的。在所有生长条件下，两种拟南芥株系（野生型Col-0和生育酚缺陷型vte1突变体）的木质部解剖结构与蒸腾速率相关，而韧皮部解剖结构与光合能力相关，与生育酚状态无关。高叶片脉密度（VD）与每条叶脉中木质部和韧皮部细胞数量及横截面积增加有关，且在高光强与低光强条件下，光合速率和蒸腾速率均较高。在高温与低温条件下，高叶片VD与较高的木质部与韧皮部比例以及蒸腾与光合的相对速率增加有关。生育酚状态影响叶片维管系统的发育，具体取决于生长环境。生育酚缺乏的最显著影响出现在高温生长条件下，vte1突变体每条叶脉中呈现出更多的管状分子（TEs），TEs与筛管分子的比例更高，单个TEs尺寸更小，且与Col-0野生型相比，每条叶脉中TEs的总面积和蒸腾速率相似。这些发现表明，通过维管系统各组成部分的独立调节，叶片维管解剖结构对生长环境具有可塑性适应。
