The gene responsible for borate cross-linking of pectin Rhamnogalacturonan-II is required for plant reproductive tissue development and fertilization
The gene responsible for borate cross-linking of pectin Rhamnogalacturonan-II is required for plant reproductive tissue development and fertilization
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DOI：
10.1073/pnas.0605141103
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发表时间：
2006-10-31
影响因子：
11.1
通讯作者：
Satoh, Shinobu
中科院分区：
文献类型：
--
作者：
Iwai, Hiroaki;Hokura, Akiko;Satoh, Shinobu
硼是高等植物生长发育所必需的微量元素，硼的缺乏常常会导致生殖生长问题。细胞壁果胶中的鼠李糖半乳糖醛酸-II (RG-II)作为植物细胞中硼的唯一受体，形成硼酸盐交联的RG-II climer (dRG-II-B)，但dRG-II-B的生理功能仍不清楚。我们之前已经表明，果胶葡萄糖醛酸转移酶 1 基因 NpGUT1 参与 RG-II 糖链的生物合成，对于 RG-II-B 复合物的形成至关重要，从而导致分生组织中紧密的细胞间附着。由于发现除分生组织外，NpGUT1 在生殖器官中也大量表达，因此我们更详细地分析了 NpGUT1 在烟草生殖组织中的表达和功能。在花芽的绒毡层、花粉、花粉管尖端和花雌蕊的传递组织中检测到特异性 NpGUT1 表达。地塞米松诱导花芽中 NpGUT1 反义基因的表达导致不育花的形成，并导致花粉和传递组织发育异常。花粉管无法通过带有败育的传递组织的雌蕊，发芽花粉中 NpGUT1 反义基因的表达抑制花粉管伸长，同时花粉管尖端缺乏果胶 RG-II 和硼。这些结果表明 NpGUT1 的表达是雄性和雌性组织的发育和功能所必需的。
Deficiencies in boron, a microelement that is essential for the growth and development of higher plants, often cause problems in reproductive growth. Rhamnogalacturonan-II (RG-II) in cell wall pectin acts as the sole receptor for boron in plant cells, forming a borate cross-linked RG-II climer (dRG-II-B), but the physiological functions of dRG-II-B remain unknown. We have previously shown that the pectin glucuronyltransferase 1 gene NpGUT1, which is involved in the biosynthesis of RG-II sugar chains, is essential for the formation of the RG-II-B complex, resulting in tight intercellular attachment in meristematic tissues. Because NpGUT1 expression was found to be abundant in reproductive organs in addition to meristematic tissues, we analyzed the expression and functions of NpGUT1 in more detail in tobacco reproductive tissues. Specific NpGUT1 expression was detected in the tapetum of flower buds and in the pollen, pollen tube tips, and transmitting tissue of the pistils of flowers. Dexamethasone-induced expression of the NpGUT1 antisense gene in flower buds resulted in the formation of sterile flowers with aberrant development of pollen and transmitting tissue. Pollen tubes could not pass through pistils with aborted transmitting tissue, and expression of an NpGUT1 antisense gene in germinating pollen inhibited pollen tube elongation, accompanied by the absence of pectin RG-II and boron in the pollen tube tip. These results indicate that expression of NpGUT1 is required for the development and functions of male and female tissues.