Zanne Amy E, Lower Steven S, Cardon Zoe G, Orians Colin M
Department of Biology, Tufts University, Medford, MA 02155, USA.
Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT 06269, USA.
Funct Plant Biol. 2006 May;33(5):457-464. doi: 10.1071/FP05299.
Allocation of root-derived resources is influenced by tissue demand; however, vascular pathways mediate resource flow from roots to shoots. In vascularly constrained plants (i.e. sectored plants), effects of vascular connections likely limit homogenous resource delivery, especially when environmental resource distribution is patchy. Here, we quantify relative roles of vascular connections, demands by different leaves (i.e. by leaf age and size), and molecule size of transported N compounds (effective sectoriality: nitrate v. ammonium) on allocation of N in the sectored tomato (Solanum lycopersicum L.). Vascular connections were the strongest predictor of both accumulation (amount per leaf; P<0.0001) and δ (estimate of concentration; P<0.0001) N values in mature leaves, but young expanding leaves did not show such dramatically sectored uptake (accumulation: P=0.0685; δ: P=0.0455), suggesting that sectoriality is less strong in young expanding tissue, especially in the youngest leaf. In patchy environments sectoriality, then, should have large consequences for the ability of a plant to allocate resources in mature tissue; however, young leaves do not appear to experience such strong vascular constraints when building new tissue.
根系衍生资源的分配受组织需求的影响；然而，维管途径介导了资源从根到地上部分的流动。在维管受限的植物（即扇形植物）中，维管连接的影响可能会限制资源的均匀输送，尤其是当环境资源分布不均时。在这里，我们量化了维管连接、不同叶片的需求（即叶片年龄和大小）以及运输的氮化合物的分子大小（有效扇形性：硝酸盐与铵盐）对扇形番茄（Solanum lycopersicum L.）中氮分配的相对作用。维管连接是成熟叶片中氮积累量（每片叶的量；P<0.0001）和δ值（浓度估计值；P<0.0001）的最强预测因子，但正在扩展的幼叶并未表现出如此显著的扇形吸收（积累量：P=0.0685；δ值：P=0.0455），这表明扇形性在正在扩展的幼嫩组织中不那么明显，尤其是在最幼嫩的叶片中。因此，在资源分布不均的环境中，扇形性对植物在成熟组织中分配资源的能力应该有很大影响；然而，幼叶在构建新组织时似乎没有受到如此强烈的维管限制。
