植物体内光合同化物韧皮部装载和卸出研究进展

近年来研究表明，植物体内光合同化物的韧皮部装载和卸出均有其本途径和质外体途径，装载转运的糖类主要有：（２）棉子糖及其人类似物（以共质体方式装载）；（２）蔗糖（以质外体方式装载）。同化物的共质体卸出可通过扩散和集中作用实现，而质外体卸出则根据蔗糖在质外体是否水解而分为两种类型。卸出和装载的途径、机理因植物种类及库源关系而不同，也会受生长发育阶段及环境的变化而调整。深入研究韧皮部装载和帛出调控机制，对

Progress in phloem Ioading and unloading of plant photoassimiate

The research of recent years shows that phloem loading and unloading of plant photoassimilate both have symplasmic and apoplasmic pathways.Sugars transported by loading mainly are(1) raffinose and its analogue (in symplasmic pathway),(2) sucrose (in apoplasmic).Symplasmic unloading of photoassimilate occurs through bulk flow and diffusion,but apoplasmic unloading is clarified into two types according whether sucrose is hydrolysable or not.The mechanisms of loading and unloading are different with plant species and the sink-source relationship of the whole plant.They also adapted with growth stages and the change of enviroment.It has important significance for theory de-velopment and practice of high-yield agriculture to study in advance the control mechanism of phloem loading and unloading.