Characterization of a cinnamoyl-CoA reductase that is associated with stem development in wheat
Characterization of a cinnamoyl-CoA reductase that is associated with stem development in wheat
复制标题
与小麦茎发育相关的肉桂酰辅酶 A 还原酶的表征
DOI：
10.1093/jxb/erm064
复制
发表时间：
2007-01-01
影响因子：
6.9
通讯作者：
Ma, Qing-Hu
中科院分区：
文献类型：
--
作者：
Ma, Qing-Hu
肉桂酰辅酶 A 还原酶 (CCR) 负责木质素单体生物合成中辅酶 A 酯向醛的转化，从而将苯丙素衍生的代谢物转移到木质素的生物合成中。为了更好地了解木质素生物合成及其生物学功能，从小麦（Triticum aestivum L.）中鉴定出编码CCR的cDNA，并将其命名为Ta-CCR1。系统发育分析表明，Ta-CCR1 与其他单子叶植物 CCR 序列组合在一起，但与 Ta-CCR2 不同。 DNA 凝胶印迹和作图分析表明 TaCCR1 在小麦基因组中作为单拷贝基因存在。重组Ta-CCR1蛋白可转化阿魏酰CoA、5-OH-阿魏酰CoA、芥子酰CoA和咖啡酰CoA，但阿魏酰CoA是最好的底物，表明优先生物合成G型木质素。 RNA凝胶印迹分析表明Ta-CCR1在茎中高表达，在叶中表达较低，在根中检测不到表达。 CCR酶活性随着木质素生物合成和茎成熟而逐渐增加。在小麦H4564品种的茎发育过程中，Ta-CCR1 mRNA水平在伸长期、抽穗期和乳汁期保持较高水平，而在C6001品种的抽穗期和乳汁期则急剧下降。在这两个品种中，Ta-CCR1 mRNA 表达与可提取的 CCR 酶活性平行。此外，小麦茎中高 Ta-CCR1 mRNA 水平和高 CCR 酶活性与 H4564 品种中更高的 Klason 木质素含量和更高的茎机械强度相关。这表明Ta-CCR1及其相关的CCR酶可能参与茎成熟过程中木质素生物合成的调节，进而有助于小麦茎的强度支持。
Cinnamoyl-CoA reductase (CCR) is responsible for the CoA ester to aldehyde conversion in monolignol biosynthesis, which diverts phenylpropanoid-derived metabolites into the biosynthesis of lignin. To gain a better understanding of lignin biosynthesis and its biological function, a cDNA encoding CCR was identified from wheat (Triticum aestivum L.), and designated as Ta-CCR1. Phylogenetic analysis indicated that Ta-CCR1 grouped together with other monocot CCR sequences while it diverged from Ta-CCR2. DNA gelblot and mapping analyses demonstrated that TaCCR1 is present as a single copy gene in the wheat genorne. Recombinant Ta-CCR1 protein converted feruloyl CoA, 5-OH-feruloyl CoA, sinapoyl CoA, and caffeoyl CoA, but feruloyi-CoA was the best substrate, suggesting the preferential biosynthesis of G-type lignin. RNA gel-blot analysis indicated that Ta-CCR1 was highly expressed in stem, with lower expression in leaves, and undetectable expression in roots. CCR enzyme activity was increased progressively along with the lignin biosynthesis and stem maturity. During stem development, Ta-CCR1 mRNA levels remained high at elongation, heading, and milky stages in the wheat H4564 cultivar, while they declined dramatically at the heading and milky stages in stems of the C6001 cultivar. Ta-CCR1 mRNA expression paralleled extractable CCR enzyme activity in these two cultivars. Furthermore, high Ta-CCR1 mRNA levels and high CCR enzyme activity in wheat stem were correlated with a higher Klason lignin content and greater stem mechanical strength in the H4564 cultivar. This suggests that Ta-CCR1 and its related CCR enzyme may be involved in the regulation of lignin biosynthesis during stem maturity and then contributes to stem strength support in wheat.