Yadav Umesh P, Shaikh Mearaj A, Evers John, Regmi Kamesh C, Gaxiola Roberto A, Ayre Brian G
BioDiscovery Institute and Department of Biological Sciences, University of North Texas, Denton, TX, USA.
Methods Mol Biol. 2019;2014:223-233. doi: 10.1007/978-1-4939-9562-2_19.
Phloem loading and long-distance transport of photoassimilate from source leaves to sink organs are essential physiological processes that contribute to plant growth and yield. At a minimum, three steps are involved: phloem loading in source organs, transport along the phloem path, and phloem unloading in sink organs. Each of these can have variable rates contingent on the physiological state of the plant, and thereby influence the overall transport rate. In addition to these phloem transport steps, rates of photosynthesis and photosynthate movement in the pre-phloem path, as well as photosynthate utilization in post phloem tissues of sink organs also contribute to phloem transport. The protocol described here estimates carbon allocation along the entire path from initial carbon fixation to delivery to sink organs after a labeling pulse: [C]CO is photoassimilated in source leaves and loading and transport of the C label to heterotrophic sink organs (roots) is quantified by scintillation counting. This method is flexible and can be adapted to quantify long-distance transport in many plant species.
韧皮部装载以及光合产物从源叶到库器官的长距离运输是有助于植物生长和产量的重要生理过程。至少涉及三个步骤：源器官中的韧皮部装载、沿韧皮部路径的运输以及库器官中的韧皮部卸载。这些步骤中的每一个都可能因植物的生理状态而具有不同的速率，从而影响整体运输速率。除了这些韧皮部运输步骤外，韧皮部前路径中的光合作用速率和光合产物移动，以及库器官韧皮部后组织中的光合产物利用也对韧皮部运输有贡献。这里描述的方案估计了从标记脉冲后最初的碳固定到输送到库器官的整个路径上的碳分配：[C]CO在源叶中被光合同化，并且通过闪烁计数对C标记物向异养库器官（根）的装载和运输进行定量。该方法具有灵活性，可适用于量化许多植物物种中的长距离运输。
