Arabidopsis transcription factor TCP4 represses chlorophyll biosynthesis to prevent petal greening

第一作者：Xinhui Zheng

第一单位：北京大学

通讯作者：Genji Qin

 Abstarct 

背景回顾：Green petals pose a challenge for pollinators to distinguish flowers from leaves, but they are valuable as a specialty flower trait. However, little is understood about the molecular mechanisms that underlie the development of green petals. 

绿色花瓣让传粉者难以从叶片中辨别出花瓣，但其作为一种特殊的花性状，具有十分重要的研究价值。但是，目前对于绿色花瓣发育的分子机制却了解不多。

主要研究：Here, we report that CINCINNATA (CIN)-like TEOSINTE BRANCHED 1/CYCLOIDEA/PCF (TCP) proteins play key roles in the control of petal color. 

本文中，作者报道了TCP蛋白在控制花瓣着色方面发挥重要功能。

结果1-突变体表型及拯救：The septuple tcp2/3/4/5/10/13/17 mutant produced flowers with green petals due to chlorophyll accumulation. Expression of TCP4 complemented the petal phenotype of tcp2/3/4/5/10/13/17. We found that chloroplasts were converted into leucoplasts in the distal parts of wild-type petals but not in the proximal parts during flower development, whereas plastid conversion was compromised in the distal parts of tcp2/3/4/5/10/13/17 petals. TCP4 and most CIN-like TCPs were predominantly expressed in distal petal regions, consistent with the green–white pattern in wild-type petals and the petal greening observed in the distal parts of tcp2/3/4/5/10/13/17 petals.

tcp2/3/4/5/10/13/17七突植株的花瓣为绿色，主要是由于叶绿色的过量积累。TCP4的表达能够互补tcp2/3/4/5/10/13/17突变体的花瓣着色表型。作者发现在野生型花发育过程中，花瓣远端的叶绿体会被转化成白色体，而近端则不会；同时，在tcp2/3/4/5/10/13/17七突植株中花瓣远端的质体转变出现缺陷。TCP4和大多数的TCPs基因优先在花瓣的远端区域表达，这与野生型花瓣中的绿-白着色模式一致，与tcp2/3/4/5/10/13/17突变体花瓣远端变绿结果也一致。

结果2-TCP4下游基因：RNA-sequencing data revealed that most chlorophyll biosynthesis genes were downregulated in the white distal parts of wild-type petals, but these genes had elevated expression in the distal green parts of tcp2/3/4/5/10/13/17 petals and the green proximal parts of wild-type petals. We revealed that TCP4 repressed chlorophyll biosynthesis by directly binding to the promoters of PROTOCHLOROPHYLLIDE REDUCTASE(PORB), DIVINYL REDUCTASE (DVR), and SUPPRESSOR OF OVEREXPRESSION OF CO 1 (SOC1), which are known to promote petal greening. We found that the conversion of chloroplasts to leucoplasts and the green coloration in the proximal parts of petals appeared to be conserved among plant species. 

转录组分析显示，野生型花瓣白色区域的叶绿素生物合成基因大多下调表达，但是这些基因在tcp2/3/4/5/10/13/17突变体的远端绿色区域以及野生型花瓣的绿色近端区域表达量都有所提升。作者发现，TCP4能够通过直接结合到PORB、DVR以及SOC1基因的启动子区抑制这些基因的表达，而这些基因具有促进花瓣着绿色的功能。作者发现叶绿体转变为白色体以及花瓣近端区域的绿色着色在不同的植物物种之间似乎是保守的。

结论：Our findings uncover a major molecular mechanism that underpins the formation of petal color patterns and provide a foundation for the breeding of plants with green flowers.

本文的研究结果揭示了一个作用于花瓣着色模式形成的主要分子机制，同时也为绿色花朵植物的育种提供了基础。

** 秦跟基 **

doi: https://doi.org/10.1016/j.xplc.2022.100309

Journal: Plant Communications

Published date: March 02, 2022​