The stylar 120 kDa glycoprotein is required for S-specific pollen rejection in Nicotiana
The stylar 120 kDa glycoprotein is required for S-specific pollen rejection in Nicotiana
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DOI：
10.1111/j.1365-313x.2005.02490.x
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发表时间：
2005-09-01
期刊：
影响因子：
7.2
通讯作者：
McClure, BA
中科院分区：
文献类型：
--
作者：
Hancock, CN;Kent, L;McClure, BA
S核糖核酸酶至少参与了三种花粉排斥机制。在烟草中，它在S特有的花粉排斥(自交不亲和)和至少两种不同的种间花粉排斥机制中起作用。S专化的花粉排斥和白花烟草花粉的排斥也需要额外的花柱蛋白。传递道特异蛋白(TTS)、120 kDa糖蛋白(120K)和雌蕊伸展素样蛋白III(PELP III)是体外结合S核糖核酸酶的花柱糖蛋白，也被认为与花粉相互作用。在这里，我们测试了这些糖蛋白是否在花粉排斥中起到了直接作用。120K在烟草种间的大小多态性最大。较大的120K样蛋白通常与S特异的花粉排斥反应有关。测序结果表明，这种多态主要反映了糖基化的差异，尽管INDELs也存在于预测的多肽中。利用RNA干扰技术，我们抑制了120K的表达，以确定它是否是S特异的花粉排斥所必需的。未检测到120K的转基因烟草S105S105或S10SC10不能产生S特异的花粉排斥反应。因此，120K在S特异的花粉排斥反应中具有直接作用。然而，抑制120K对白花丹花粉的排斥作用不明显。相反，抑制HT-B，一个先前与S特异的花粉排斥有关的因素，破坏了对白花蛇舌兰花粉的排斥。因此，S专化的花粉排斥和白花丹花粉的排斥在机理上是不同的，因为它们需要不同的非S核糖核酸酶因子。
S-RNase participates in at least three mechanisms of pollen rejection. It functions in S-specific pollen rejection (self-incompatibility) and in at least two distinct interspecific mechanisms of pollen rejection in Nicotiana. S-specific pollen rejection and rejection of pollen from Nicotiana plumbaginifolia also require additional stylar proteins. Transmitting-tract-specific (TTS) protein, 120 kDa glycoprotein (120K) and pistil extensin-like protein III (PELP III) are stylar glycoproteins that bind S-RNase in vitro and are also known to interact with pollen. Here we tested whether these glycoproteins have a direct role in pollen rejection. 120K shows the most polymorphism in size between Nicotiana species. Larger 120K-like proteins are often correlated with S-specific pollen rejection. Sequencing results suggest that the polymorphism primarily reflects differences in glycosylation, although indels also occur in the predicted polypeptides. Using RNA interference (RNAi), we suppressed expression of 120K to determine if it is required for S-specific pollen rejection. Transgenic SC N. plumbaginifolia x SI Nicotiana alata (S105S105 or SC10SC10) hybrids with no detectable 120K were unable to perform S-specific pollen rejection. Thus, 120K has a direct role in S-specific pollen rejection. However, suppression of 120K had no effect on rejection of N. plumbaginifolia pollen. In contrast, suppression of HT-B, a factor previously implicated in S-specific pollen rejection, disrupts rejection of N. plumbaginifolia pollen. Thus, S-specific pollen rejection and rejection of N. plumbaginifolia pollen are mechanistically distinct, because they require different non-S-RNase factors.