Alterations in CER6, a gene identical to CUT1, differentially affect long-chain lipid content on the surface of pollen and stems
Alterations in CER6, a gene identical to CUT1, differentially affect long-chain lipid content on the surface of pollen and stems
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DOI：
10.1105/tpc.12.10.2001
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发表时间：
2000-10-01
期刊：
影响因子：
11.6
通讯作者：
Preuss, D
中科院分区：
文献类型：
--
作者：
Fiebig, A;Mayfield, JA;Preuss, D
极长链脂质是所有陆生植物表面疏水角质层的重要组成部分，也是菊科植物花粉外被的重要组成部分。拟南芥CER基因的突变会从角质层表面消除非常长的链脂质，在某些情况下，还会从花粉外皮中消除。在拟南芥中，花粉外皮脂质的丢失会破坏与柱头的相互作用，抑制花粉水合作用并导致不育。我们已经定位克隆CER 6，并证明野生型拷贝补充cer 6 -2缺陷。此外，我们已经确定了一个肥沃的，基因内抑制，cer 6 - 2 R，部分恢复花粉外壳脂质，但不拯救茎蜡缺陷，表明一个有趣的差异，要求CER 6活性的茎和花粉外壳。重要的是，这种抑制剂的分析表明，少量的非常长链的脂质是足够的花粉水合和萌发。预测的CER 6氨基酸序列类似于脂肪酸缩合酶的氨基酸序列，这与其在产生>28个碳长的表皮和花粉衣脂质中的作用一致。DNA序列分析揭示了cer 6 -1、cer 6 -2和cer 6 - 2 R突变的性质，分离分析表明，CER 6与CUT 1相同，CUT 1是一个先前定位在不同染色体臂上的cDNA，相反，我们确定了一个新的基因，CER 60，与CER 6具有高度的核苷酸和氨基酸相似性，位于原始的CUT 1位点。
Very long chain lipids contribute to the hydrophobic cuticle on the surface of all land plants and are an essential component of the extracellular pollen coat in the Brassicaceae. Mutations in Arabidopsis CER genes eliminate very long chain lipids from the cuticle surface and, in some cases, from the pollen coat, in Arabidopsis, the loss of pollen coat lipids can disrupt interactions with the stigma, inhibiting pollen hydration and causing sterility. We have positionally cloned CER6 and demonstrate that a wild-type copy complements the cer6-2 defect. In addition, we have identified a fertile, intragenic suppressor, cer6-2R, that partially restores pollen coat lipids but does not rescue the stem wax defect, suggesting an intriguing difference in the requirements for CER6 activity on stems and the pollen coat. Importantly, analysis of this suppressor demonstrates that low amounts of very long chain lipids are sufficient for pollen hydration and germination. The predicted CER6 amino acid sequence resembles that of fatty acid-condensing enzymes, consistent with its role in the production of epicuticular and pollen coat lipids >28 carbons long. DNA sequence analysis revealed the nature of the cer6-1, cer6-2, and cer6-2R mutations, and segregation analysis showed that CER6 is identical to CUT1, a cDNA previously mapped to a different chromosome arm. Instead, we have determined that a new gene, CER60, with a high degree of nucleotide and amino acid similarity to CER6, resides at the original CUT1 locus.