Angiosperm leaf vein evolution was physiologically and environmentally transformative
Angiosperm leaf vein evolution was physiologically and environmentally transformative
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DOI：
10.1098/rspb.2008.1919
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发表时间：
2009-05-22
影响因子：
4.7
通讯作者：
Zwieniecki, Maciej A.
中科院分区：
文献类型：
--
作者：
Boyce, C. Kevin;Brodribb, Tim J.;Zwieniecki, Maciej A.
在光合作用过程中灌溉叶片的脉被证明在显花植物中比在任何其他维管植物谱系中更丰富。被子植物的叶脉密度平均为每平方毫米叶面积8毫米，可以达到25毫米，而如此高的密度在所有其他植物中是不存在的，无论是现存的还是灭绝的。非被子植物的叶子在3.8亿年的进化过程中一直平均接近2 mm mm（-2），尽管有一个复杂的历史，涉及四个或更多独立的具有许多纹理的层压叶的起源以及气候和大气成分的巨大变化。我们进一步证明，高叶脉密度独特的被子植物，使无与伦比的蒸腾速率，扩展以前的工作表明静脉密度和同化率之间的强相关性。由于矿脉密度在化石中是可以直接测量的，这些相关性为研究灭绝植物的生理学以及它们如何影响环境提供了新的途径。首先，目前仅限于活体植物中被子植物的高同化率可能在整个进化史上是独一无二的。第二，在被子植物出现之前的世界，蒸腾驱动的水循环对现代热带雨林的降水量很重要，但可能要少得多。
The veins that irrigate leaves during photosynthesis are demonstrated to be strikingly more abundant in flowering plants than in any other vascular plant lineage. Angiosperm vein densities average 8 mm of vein per mm(-2) of leaf area and can reach 25 mm mm(-2), whereas such high densities are absent from all other plants, living or extinct. Leaves of non-angiosperms have consistently averaged close to 2 mm mm(-2) throughout 380 million years of evolution despite a complex history that has involved four or more independent origins of laminate leaves with many veins and dramatic changes in climate and atmospheric composition. We further demonstrate that the high leaf vein densities unique to the angiosperms enable unparalleled transpiration rates, extending previous work indicating a strong correlation between vein density and assimilation rates. Because vein density is directly measurable in fossils, these correlations provide new access to the physiology of extinct plants and how they may have impacted their environments. First, the high assimilation rates currently confined to the angiosperms among living plants are likely to have been unique throughout evolutionary history. Second, the transpiration-driven recycling of water that is important for bolstering precipitation in modern tropical rainforests might have been significantly less in a world before the angiosperms.