Department of Ecology and Evolutionary Biology, University of Connecticut, 75 North Eagleville Road, Storrs, CT, 06269-3043, USA.
New Phytol. 2021 Aug;231(3):933-949. doi: 10.1111/nph.17397. Epub 2021 May 28.
Anthocyanins play a variety of adaptive roles in both vegetative tissues and reproductive organs of plants. The broad functionality of these compounds requires sophisticated regulation of the anthocyanin biosynthesis pathway to allow proper localization, timing, and optimal intensity of pigment deposition. While it is well-established that the committed steps of anthocyanin biosynthesis are activated by a highly conserved MYB-bHLH-WDR (MBW) protein complex in virtually all flowering plants, anthocyanin repression seems to be achieved by a wide variety of protein and small RNA families that function in different tissue types and in response to different developmental, environmental, and hormonal cues. In this review, we survey recent progress in the identification of anthocyanin repressors and the characterization of their molecular mechanisms. We find that these seemingly very different repression modules act through a remarkably similar logic, the so-called 'double-negative logic'. Much of the double-negative regulation of anthocyanin production involves signal-induced degradation or sequestration of the repressors from the MBW protein complex. We discuss the functional and evolutionary advantages of this logic design compared with simple or sequential positive regulation. These advantages provide a plausible explanation as to why plants have evolved so many anthocyanin repressors.
花色素苷在植物的营养组织和生殖器官中发挥着多种适应性作用。这些化合物的广泛功能需要对花色素苷生物合成途径进行精细调控,以允许色素沉积的适当定位、时间和最佳强度。虽然人们已经充分认识到,在几乎所有开花植物中,花色素苷生物合成的关键步骤是由一个高度保守的 MYB-bHLH-WDR(MBW)蛋白复合物激活的,但花色素苷的抑制似乎是由多种在不同组织类型中发挥作用并对不同发育、环境和激素信号作出反应的蛋白质和小 RNA 家族实现的。在这篇综述中,我们调查了花色素苷抑制剂的鉴定和分子机制特征方面的最新进展。我们发现,这些看似非常不同的抑制模块通过一种非常相似的逻辑起作用,即所谓的“双负逻辑”。花色素苷产生的大部分双负调控都涉及到信号诱导的抑制剂从 MBW 蛋白复合物中的降解或隔离。我们讨论了与简单或顺序正调控相比,这种逻辑设计的功能和进化优势。这些优势为植物为何进化出如此多的花色素苷抑制剂提供了一个合理的解释。