Plants form calluses and regenerate new organs when incubated on phytohormone-containing media. While accumulating evidence suggests that these regenerative processes are governed by transcriptional networks orchestrating wound response and developmental transitions, it remains unknown if posttranslational regulatory mechanisms are involved in this process. In this study, we demonstrate that SAP AND MIZ1 DOMAIN- CONTAINING LIGASE1 (SIZ1), an E3 ligase-catalyzing attachment of the SMALL UBIQUITIN-LIKE MODIFIER (SUMO) to proteins, regulates wound-induced signal transduction and organ regeneration in Arabidopsis (Arabidopsis thaliana). We show that loss-of-function mutants for SIZ1 exhibit overproduction of shoot meristems under in vitro tissue culture conditions, while this defect is rescued in a complementation line expressing pSIZ1::SIZ1. RNA sequencing analysis revealed that siz1-2 mutants exhibit enhanced transcriptional responses to wound stress, resulting in the hyper-induction of over 400 genes immediately after wounding. Among them, we show that elevated levels of WOUND INDUCED DEDIFFERENTIATION1 (WIND1) and WIND2 contribute to the enhanced shoot regeneration observed in siz1 mutants, as expression of the dominant-negative chimeric protein WIND1-SRDX (SUPERMAN repression domain) in siz1-3 mutants partly rescues this phenotype. Although compromised SIZ1 function does not modify the transcription of genes implicated in auxin-induced callus formation and/or pluripotency acquisition, it does lead to enhanced induction of cytokinin-induced shoot meristem regulators such as WUSCHEL, promoting the formation of WUSCHEL-expressing foci in explants. This study thus suggests that SIZ1 negatively regulates shoot regeneration in part by repressing wound-induced developmental reprogramming.

当植物在含有植物激素的培养基上培育时，会形成愈伤组织并再生新的器官。虽然越来越多的证据表明这些再生过程是由协调伤口反应和发育转变的转录网络控制的，但翻译后调节机制是否参与该过程仍然未知。在本研究中，我们证明 SAP 和 MIZ1 结构域包含的连接酶 1 (SIZ1) 是一种 E3 连接酶催化小泛素样修饰剂 (SUMO) 与蛋白质的连接，调节拟南芥中伤口诱导的信号转导和器官再生。拟南芥）。我们发现， SIZ1的功能丧失突变体在体外组织培养条件下表现出芽分生组织的过度生成，而这种缺陷在表达pSIZ1 :: SIZ1的互补系中得到了挽救。RNA测序分析显示，siz1-2突变体对伤口应激表现出增强的转录反应，导致受伤后立即过度诱导超过400个基因。其中，我们发现伤口诱导去分化1（WIND1）和WIND2水平升高有助于在siz1突变体中观察到的芽再生增强，因为siz1-3突变体中显性失活嵌合蛋白WIND1-SRDX（SUPERMAN抑制域）的表达部分挽救了这种表型。虽然受损的SIZ1功能不会改变与生长素诱导的愈伤组织形成和/或多能性获得相关的基因的转录，但它确实会导致细胞分裂素诱导的芽分生组织调节因子（例如WUSCHEL）的诱导增强，从而促进 WUSCHEL 表达灶的形成。外植体。因此，这项研究表明，SIZ1 部分通过抑制伤口诱导的发育重编程来负向调节芽再生。