MYB75 Functions in Regulation of Secondary Cell Wall Formation in the Arabidopsis Inflorescence Stem
MYB75 Functions in Regulation of Secondary Cell Wall Formation in the Arabidopsis Inflorescence Stem
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DOI：
10.1104/pp.110.162735
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发表时间：
2010-11-01
期刊：
影响因子：
7.4
通讯作者：
Ellis, Brian E.
中科院分区：
文献类型：
--
作者：
Bhargava, Apurva;Mansfield, Shawn D.;Ellis, Brian E.
植物木质化次生细胞壁的沉积主要涉及以多糖和苯丙类成分形式存在的碳骨架。这一过程在空间和时间上受到转录因子的调控，包括一些MYB家族转录因子。MYB75，也被称为花青素色素的生产1，是已知的拟南芥（拟南芥）苯丙素途径花青素分支的调节剂，但这种调节如何影响碳代谢的其他方面尚不清楚。我们发现MYB75 （MYB75 -1）的功能缺失突变导致花序茎内木质部和束间纤维细胞壁厚度增加。木质素单体的总木质素含量和S/G比也受到影响。来自myb75-1花序茎的转录谱显示，与木质素生物合成和纤维素沉积相关的一系列基因、细胞壁修饰蛋白和参与光合作用和碳同化的基因的表达明显上调。这些模式表明MYB75作为苯丙素途径木质素分支的抑制因子。由于MYB75与另一种次生细胞壁调节因子KNOX转录因子KNAT7相互作用，这些调节蛋白可能形成功能复合物，参与调控拟南芥花茎的次生细胞壁沉积，并通过木质素、类黄酮和多糖途径整合代谢通量。
Deposition of lignified secondary cell walls in plants involves a major commitment of carbon skeletons in both the form of polysaccharides and phenylpropanoid constituents. This process is spatially and temporally regulated by transcription factors, including a number of MYB family transcription factors. MYB75, also called PRODUCTION OF ANTHOCYANIN PIGMENT1, is a known regulator of the anthocyanin branch of the phenylpropanoid pathway in Arabidopsis (Arabidopsis thaliana), but how this regulation might impact other aspects of carbon metabolism is unclear. We established that a loss-of-function mutation in MYB75 (myb75-1) results in increased cell wall thickness in xylary and interfascicular fibers within the inflorescence stem. The total lignin content and S/G ratio of the lignin monomers were also affected. Transcript profiles from the myb75-1 inflorescence stem revealed marked up-regulation in the expression of a suite of genes associated with lignin biosynthesis and cellulose deposition, as well as cell wall modifying proteins and genes involved in photosynthesis and carbon assimilation. These patterns suggest that MYB75 acts as a repressor of the lignin branch of the phenylpropanoid pathway. Since MYB75 physically interacts with another secondary cell wall regulator, the KNOX transcription factor KNAT7, these regulatory proteins may form functional complexes that contribute to the regulation of secondary cell wall deposition in the Arabidopsis inflorescence stem and that integrate the metabolic flux through the lignin, flavonoid, and polysaccharide pathways.