Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Campus UAB, Bellaterra, Barcelona, Spain.
J Exp Bot. 2019 Apr 12;70(7):2087-2095. doi: 10.1093/jxb/erz030.
The hypersensitive response (HR) is a plant defence reaction triggered by activation of immune receptors upon pathogen recognition. It results in rapid cell death at the attempted invasion site, confining the pathogen and sending signals to distal parts of the plant that can in turn activate defences for subsequent attacks. HR cell death is a highly controlled phenomenon, requiring the concerted action of diverse plant proteases and regulatory mechanisms to keep it efficient yet confined. Research in the last decade has significantly contributed to a better understanding of the mechanisms leading to HR, although our knowledge about the pathways that regulate this form of programmed cell death (PCD) still remains incomplete. In this review, we explore current knowledge of plant proteases as HR regulators. Proteases are key regulatory enzymes that not only serve degradative purposes, but also have very important signalling roles. In animals, caspases have been shown to be the major regulators and executioners of PCD. Plants do not have caspases, and instead PCD is carried out by the activities of caspase-like and other protease belonging to different protease classes. We summarise the mechanistic roles of plant proteases whose roles in HR regulation are relatively well understood, which includes members of the cysteine, threonine, and serine protease families.
超敏反应 (HR) 是一种植物防御反应，当病原体识别免疫受体被激活时就会触发。它会导致在试图入侵的部位迅速发生细胞死亡，从而限制病原体的传播，并向植物的远端部位发送信号，从而可以激活针对后续攻击的防御机制。HR 细胞死亡是一种高度受控的现象，需要各种植物蛋白酶和调节机制的协同作用，以保持其高效性和局限性。在过去的十年中，研究显著促进了对导致 HR 的机制的更好理解，尽管我们对调节这种形式的程序性细胞死亡 (PCD) 的途径的了解仍然不完整。在这篇综述中，我们探讨了植物蛋白酶作为 HR 调节剂的最新知识。蛋白酶是关键的调节酶，不仅具有降解作用，而且还具有非常重要的信号作用。在动物中，已经证明半胱氨酸蛋白酶是 PCD 的主要调节因子和执行者。植物没有半胱氨酸蛋白酶，而是通过半胱氨酸蛋白酶样和其他属于不同蛋白酶类别的蛋白酶的活性来执行 PCD。我们总结了植物蛋白酶的作用机制，其中一些蛋白酶在 HR 调节中的作用相对明确，包括半胱氨酸蛋白酶、苏氨酸蛋白酶和丝氨酸蛋白酶家族的成员。
