GOLD HULL AND INTERNODE2 Encodes a Primarily Multifunctional Cinnamyl-Alcohol Dehydrogenase in Rice1
GOLD HULL AND INTERNODE2 Encodes a Primarily Multifunctional Cinnamyl-Alcohol Dehydrogenase in Rice1
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DOI：
10.1104/pp.105.073007
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发表时间：
2006-01
期刊：
影响因子：
7.4
通讯作者：
Kewei Zhang;Q. Qian;Zejun Huang;Yiqin Wang;Ming Li;Lilan Hong;D. Zeng;M. Gu;Chengcai Chu
中科院分区：
文献类型：
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作者：
Kewei Zhang;Q. Qian;Zejun Huang;Yiqin Wang;Ming Li;Lilan Hong;D. Zeng;M. Gu;Chengcai Chu
木质素含量和组成是影响农业废弃物利用的两个重要农艺性状。水稻金壳和节间表型是一种经典的形态标记性状，长期以来一直被应用于育种和遗传学研究。在本研究中，我们利用基于图谱的克隆方法克隆了水稻的GH2基因。结果表明，该突变体为木质素缺失突变体，编码肉桂醇脱氢酶(CAD)。与这一发现一致的是，GH2植物的根、节间、外壳和圆锥花序的提取物显示出显著的CAD活性降低和检测不到的芥子醇脱氢酶活性。在大肠杆菌中表达时，纯化的重组GH2对针叶醛和芥子醛具有很强的催化能力，而突变蛋白GH2完全失去了相应的CAD和芥子醇脱氢酶活性。对GH2突变体植株的进一步表型分析表明，与野生型相比，对羟基苯基、愈创木基和芥子基单体的减少比例几乎相同。我们的结果表明，GH2在水稻木质素生物合成中作为一个主要的多功能CAD来合成针叶醇和芥子醇前体。
Lignin content and composition are two important agronomic traits for the utilization of agricultural residues. Rice (Oryza sativa) gold hull and internode phenotype is a classical morphological marker trait that has long been applied to breeding and genetics study. In this study, we have cloned the GOLD HULL AND INTERNODE2 (GH2) gene in rice using a map-based cloning approach. The result shows that the gh2 mutant is a lignin-deficient mutant, and GH2 encodes a cinnamyl-alcohol dehydrogenase (CAD). Consistent with this finding, extracts from roots, internodes, hulls, and panicles of the gh2 plants exhibited drastically reduced CAD activity and undetectable sinapyl alcohol dehydrogenase activity. When expressed in Escherichia coli, purified recombinant GH2 was found to exhibit strong catalytic ability toward coniferaldehyde and sinapaldehyde, while the mutant protein gh2 completely lost the corresponding CAD and sinapyl alcohol dehydrogenase activities. Further phenotypic analysis of the gh2 mutant plants revealed that the p-hydroxyphenyl, guaiacyl, and sinapyl monomers were reduced in almost the same ratio compared to the wild type. Our results suggest GH2 acts as a primarily multifunctional CAD to synthesize coniferyl and sinapyl alcohol precursors in rice lignin biosynthesis.