基因组进化过程中基因重复产生的旁系同源物能够实现遗传冗余和表型稳健性。旁系转录调节子的编码或调节序列的变化使它们的功能和关系多样化。它提供了对抗遗传或环境扰动的发育稳健性。为了开花和繁殖成功,植物芽干细胞的命运转变需要强大的转录控制。然而,旁系物如何发挥作用和相互作用以实现这种鲁棒性是未知的。
这里,我们探讨了芽分生组织中具有不同转录丰度的ALOG家族转录因子的遗传关系和蛋白质行为。突变谱涵盖五个ALOG旁系同源物的单个和更高阶突变组合,并产生连续的开花过渡缺陷,表现出逐渐增强的早熟开花,随着花序的简化,从野生型到逐渐减少的花,直到单生的花具有不育的花器官。因此,这些旁系同源物扮演着不平等的角色,共同作用,实现了强大的遗传渠道化。所有五种蛋白质都含有朊病毒样固有无序区域(IDR)并经历相分离。基因重复后累积的突变导致ALOG旁系同源物之间的IDR变异,导致不同的相分离和转录调节能力。值得注意的是,它们保留了祖先组装成异型缩合物的能力,从而防止了花身份基因ANANTHA的早熟激活。
我们的研究揭示了一种新的遗传管化机制,该机制是由旁系蛋白质相互作用和相分离形成的异型转录缩合物实现的。揭示基因重复之间的分子联系导致IDR变异和干细胞命运转变的强大转录控制。
Paralogs that arise from gene duplications during genome evolution enable genetic redundancy and phenotypic robustness. Variation in the coding or regulatory sequence of paralogous transcriptional regulators diversifies their functions and relationships, which provides developmental robustness against genetic or environmental perturbation. The fate transition of plant shoot stem cells for flowering and reproductive success requires a robust transcriptional control. However, how paralogs function and interact to achieve such robustness is unknown.
Here, we explore the genetic relationship and protein behavior of ALOG family transcriptional factors with diverse transcriptional abundance in shoot meristems. A mutant spectrum covers single and higher-order mutant combinations of five ALOG paralogs and creates a continuum of flowering transition defects, showing gradually enhanced precocious flowering, along with inflorescence simplification from wild-type-like to progressively fewer flowers until solitary flower with sterile floral organs. Therefore, these paralogs play unequal roles and act together to achieve a robust genetic canalization. All five proteins contain prion-like intrinsically disordered regions (IDRs) and undergo phase separation. Accumulated mutations following gene duplications lead to IDR variations among ALOG paralogs, resulting in divergent phase separation and transcriptional regulation capabilities. Remarkably, they retain the ancestral abilities to assemble into a heterotypic condensate that prevents precocious activation of the floral identity gene ANANTHA.
Our study reveals a novel genetic canalization mechanism enabled by heterotypic transcriptional condensates formed by paralogous protein interactions and phase separation, uncovering the molecular link between gene duplication caused IDR variation and robust transcriptional control of stem cell fate transition.