Institute of Plant Science and Resources, Okayama University, Chuo 2-20-1, Kurashiki 710-0046, Japan.
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China.
Plant Physiol. 2018 Feb;176(2):1739-1750. doi: 10.1104/pp.17.01641. Epub 2017 Dec 7.
Boron is especially required for the growth of meristem and reproductive organs, but the molecular mechanisms underlying the preferential distribution of B to these developing tissues are poorly understood. Here, we show evidence that a member of nodulin 26-like intrinsic protein (NIP), OsNIP3;1, is involved in this preferential distribution in rice (). ; was highly expressed in the nodes and its expression was up-regulated by B deficiency, but down-regulated by high B. OsNIP3;1 was polarly localized at the xylem parenchyma cells of enlarged vascular bundles of nodes facing toward the xylem vessels. Furthermore, this protein was rapidly degraded within a few hours in response to high B. Knockout of this gene hardly affected the uptake and root-to-shoot translocation of B, but altered B distribution in different organs in the above-ground parts, decreased distribution of B to the new leaves, and increased distribution to the old leaves. These results indicate that OsNIP3;1 located in the nodes is involved in the preferential distribution of B to the developing tissues by unloading B from the xylem in rice and that it is regulated at both transcriptional and protein level in response to external B level.
硼对茎尖分生组织和生殖器官的生长尤为重要，但硼优先分配到这些发育组织的分子机制还知之甚少。在这里，我们证明了一个 nodulin 26 样内在蛋白（NIP）成员，OsNIP3;1，参与了水稻中的这种优先分布。（）在节中高度表达，其表达受 B 缺乏诱导而上调，但受高 B 下调。OsNIP3;1 极性定位于节点中面向木质部导管的大维管束的木质部薄壁细胞。此外，这种蛋白在几小时内对高 B 迅速降解。该基因的敲除几乎不影响 B 的摄取和根到茎的转运，但改变了地上部分不同器官中 B 的分布，减少了 B 向新叶的分配，增加了向老叶的分配。这些结果表明，OsNIP3;1 位于节点中，通过从木质部中卸载 B 参与了水稻中 B 向发育组织的优先分配，并且它在转录和蛋白水平上都受到外部 B 水平的调节。
