A MYB Triad Controls Primary and Phenylpropanoid Metabolites for Pollen Coat Patterning
A MYB Triad Controls Primary and Phenylpropanoid Metabolites for Pollen Coat Patterning
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DOI：
10.1104/pp.19.00009
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发表时间：
2019-05-01
期刊：
影响因子：
7.4
通讯作者：
Aharoni, Asaph
中科院分区：
文献类型：
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作者：
Battat, Maor;Eitan, Asa;Aharoni, Asaph
花粉壁是植物繁殖所必需的复杂、持久的结构。花粉粒绒毡层细胞产生的大量苯丙素（如黄酮醇）沉积在花粉壁中。花粉壁形成的转录调控已被广泛研究，并提出了拟南芥（Arabidopsis thaliana）花粉黄酮醇生物合成的特定调控机制。本研究通过对突变型和过表达型花药的代谢组学和转录组学分析发现，拟南芥MYB99是矮牵牛（petunia hybrida）花香调节剂ODORANT1 （ODO1）的同源基因，控制绒毡层二糖基化黄酮醇和羟基肉桂酸酰胺的特异性产生。我们发现MYB99与MYB21和MYB24是一个调控三联体，MYB21和MYB24是苯类化合物I和II的释放同源物，它们与ODO1共同调控矮牵牛花气味生物合成基因。此外，启动子激活实验表明，MYB99通过控制TRANSKETOLASE2的表达，将初级代谢中的卡尔文循环和氧化戊糖-磷酸途径的前体供应导向苯丙素生物合成。我们提供了一个模型，描述了拟南芥MYB三联体与初级和苯丙素代谢结构基因之间的关系，并将这种机制与矮牵牛花气味控制进行了比较。同源蛋白三联体产生相关次生代谢物的发现表明，类似的调节模块存在于其他植物中，并作用于调节复杂的苯丙素途径的各个分支。
The pollen wall is a complex, durable structure essential for plant reproduction. A substantial portion of phenylpropanoids (e.g. flavonols) produced by pollen grain tapetal cells are deposited in the pollen wall. Transcriptional regulation of pollen wall formation has been studied extensively, and a specific regulatory mechanism for Arabidopsis (Arabidopsis thaliana) pollen flavonol biosynthesis has been postulated. Here, metabolome and transcriptome analyses of anthers from mutant and overexpression genotypes revealed that Arabidopsis MYB99, a putative ortholog of the petunia (Petunia hybrida) floral scent regulator ODORANT1 (ODO1), controls the exclusive production of tapetum diglycosylated flavonols and hydroxycinnamic acid amides. We discovered that MYB99 acts in a regulatory triad with MYB21 and MYB24, orthologs of emission of benzenoids I and II, which together with ODO1 coregulate petunia scent biosynthesis genes. Furthermore, promoter-activation assays showed that MYB99 directs precursor supply from the Calvin cycle and oxidative pentose-phosphate pathway in primary metabolism to phenylpropanoid biosynthesis by controlling TRANSKETOLASE2 expression. We provide a model depicting the relationship between the Arabidopsis MYB triad and structural genes from primary and phenylpropanoid metabolism and compare this mechanism with petunia scent control. The discovery of orthologous protein triads producing related secondary metabolites suggests that analogous regulatory modules exist in other plants and act to regulate various branches of the intricate phenylpropanoid pathway.