Li Nan, Xu Yunzhang, Lu Yingqing
State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Plants (Basel). 2024 Apr 22;13(8):1156. doi: 10.3390/plants13081156.
Genes of metabolic pathways are individually or collectively regulated, often via unclear mechanisms. The anthocyanin pathway, well known for its regulation by the MYB/bHLH/WDR (MBW) complex but less well understood in its connections to MYC2, BBX21, SPL9, PIF3, and HY5, is investigated here for its direct links to the regulators. We show that MYC2 can activate the structural genes of the anthocyanin pathway but also suppress them (except ) in both and when a local MBW complex is present. BBX21 or SPL9 can activate all or part of the structural genes, respectively, but the effects can be largely overwritten by the local MBW complex. HY5 primarily influences expressions of the early genes (, , and ). TF-TF relationships can be complex here: PIF3, BBX21, or SPL9 can mildly activate ; MYC2 physically interacts with the bHLH (GL3) of the MBW complex and/or competes with strong actions of BBX21 to lessen a stimulus to the anthocyanin pathway. The dual role of MYC2 in regulating the anthocyanin pathway and a similar role of BBX21 in regulating reveal a network-level mechanism, in which pathways are modulated locally and competing interactions between modulators may tone down strong environmental signals before they reach the network.
代谢途径的基因通常通过尚不清楚的机制被单独或共同调控。花青素途径以其受MYB/bHLH/WDR（MBW）复合体调控而闻名，但在与MYC2、BBX21、SPL9、PIF3和HY5的联系方面了解较少，本文对其与这些调控因子的直接联系进行了研究。我们发现，在存在局部MBW复合体的情况下，MYC2在拟南芥和烟草中既能激活花青素途径的结构基因，也能抑制它们（除了……）。BBX21或SPL9可以分别激活全部或部分结构基因，但这些作用在很大程度上会被局部MBW复合体覆盖。HY5主要影响早期基因（……、……和……）的表达。这里的转录因子-转录因子关系可能很复杂：PIF3、BBX21或SPL9可以轻度激活……；MYC2与MBW复合体的bHLH（GL3）发生物理相互作用和/或与BBX21的强烈作用竞争，以减轻对花青素途径的刺激。MYC2在调控花青素途径中的双重作用以及BBX21在调控……中的类似作用揭示了一种网络水平的机制，即途径在局部受到调节，调节因子之间的竞争性相互作用可能在强烈的环境信号到达网络之前就减弱它们。
