Key Laboratory of Economic Plants and Biotechnology, Yunnan Key Laboratory for Wild Plant Resources, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, Yunnan, China.
School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania, 7001, Australia.
New Phytol. 2018 Sep;219(4):1224-1234. doi: 10.1111/nph.15210. Epub 2018 May 15.
Investment in leaf veins (supplying xylem water) is balanced by stomatal abundance, such that sufficient water transport is provided for stomata to remain open when soil water is abundant. This coordination is mediated by a common dependence of vein and stomatal densities on cell size. Flowers may not conform to this same developmental pattern if they depend on water supplied by the phloem or have high rates of nonstomatal transpiration. We examined the relationships between veins, stomata and epidermal cells in leaves, sepals and petals of 27 angiosperms to determine whether common spacing rules applied to all tissues. Regression analysis found no evidence for different relationships within organ types. Both vein and stomatal densities were strongly associated with epidermal cell size within organs, but, for a given epidermal cell size, petals had fewer veins and stomata than sepals, which had fewer than leaves. Although our data support the concept of common scaling between veins and stomata in leaves and flowers, the large diversity in petal vein density suggests that, in some species, petal veins may be engaged in additional functions, such as the supply of water for high cuticular transpiration or for phloem delivery of water or carbohydrates.
投资于叶脉（为木质部供水）与气孔密度相平衡，使得在土壤水分充足时，有足够的水分运输来保持气孔开放。这种协调是通过叶脉和气孔密度对细胞大小的共同依赖性来介导的。如果花依赖韧皮部供应的水，或者具有较高的非气孔蒸腾速率，则可能不符合这种相同的发育模式。我们研究了 27 种被子植物叶片、萼片和花瓣中的叶脉、气孔和表皮细胞之间的关系，以确定是否所有组织都适用共同的间距规则。回归分析没有发现器官类型内不同关系的证据。在器官内，叶脉和气孔密度与表皮细胞大小强烈相关，但对于给定的表皮细胞大小，花瓣的叶脉和气孔比萼片少，而萼片比叶片少。尽管我们的数据支持叶片和花朵中叶脉和气孔之间共同缩放的概念，但花瓣脉密度的多样性很大，表明在某些物种中，花瓣脉可能参与了其他功能，例如为高角质层蒸腾或韧皮部输送水或碳水化合物提供水分。
