Azizpor Pakeeza, Sullivan Lucy, Lim Aedric, Groover Andrew
US Forest Service, Pacific Southwest Research Station, Davis, CA, United States.
Front Plant Sci. 2022 Feb 10;13:809923. doi: 10.3389/fpls.2022.809923. eCollection 2022.
Sieve elements of many angiosperms contain structural phloem proteins (P-proteins) that can interact to create large P-protein bodies. P-protein bodies can occlude sieve plates upon injury but the range of functional and physiological roles of P-proteins remains uncertain, in part because of challenges in labeling and visualization methods. Here, we show that a reciprocal oligosaccharide probe, OGA, can be used in rapid and sensitive labeling of P-protein bodies in Arabidopsis, poplar, snap bean and cucumber in histological sections. OGA labeling of knockouts of the two Arabidopsis P-protein-encoding genes, and , indicated that labeling is specific to AtSEOR2. That protein bodies were labeled and visible in knockouts indicates that heterodimerization of AtSEOR1 and AtSEOR2 may not be necessary for P-protein body formation. Double labeling with a previously characterized stain for P-proteins, sulphorhodamine 101, confirmed P-protein labeling and also higher specificity of OGA for P-proteins. OGA is thus robust and easily used to label P-proteins in histological sections of multiple angiosperm species.
许多被子植物的筛管分子含有结构性韧皮部蛋白（P蛋白），这些蛋白可以相互作用形成大型P蛋白体。P蛋白体在受伤时可堵塞筛板，但P蛋白的功能和生理作用范围仍不确定，部分原因是标记和可视化方法存在挑战。在这里，我们表明，一种相互作用的寡糖探针OGA可用于在组织切片中快速、灵敏地标记拟南芥、杨树、菜豆和黄瓜中的P蛋白体。对拟南芥两个P蛋白编码基因AtSEOR1和AtSEOR2的敲除植株进行OGA标记，结果表明标记对AtSEOR2具有特异性。在AtSEOR1敲除植株中蛋白体被标记且可见，这表明AtSEOR1和AtSEOR2的异源二聚化可能不是P蛋白体形成所必需的。用先前表征的P蛋白染色剂磺基罗丹明101进行双重标记，证实了P蛋白标记，也证实了OGA对P蛋白具有更高的特异性。因此，OGA功能强大，易于用于标记多种被子植物物种组织切片中的P蛋白。
