The hypersensitive response (HR) is a defense action against pathogen ingression. Typically, HR is predictable with the appearance of the dead, brown cells along with visible lesions. Although death during HR can be limited to the cells in direct contact with pathogens, yet cell death can also spread away from the infection site. The variety in morphologies of plant cell death proposes involvement of different pathways for triggering HR. It is considered that, despite the differences, HR in plants performs the resembling functions like that of animal programmed cell death (PCD) for confining pathogen progression. HR, in fact, crucially initiates systemic signals for activation of defense in distal plant parts that ultimately results in systemic acquired resistance (SAR). Therefore, HR can be separated from other local immune actions/responses at the infection site. HR comprises of serial events inclusive of transcriptional reprograming, Ca2+ influx, oxidative bursts and phyto-hormonal signaling. Although a lot of work has been done on HR in plants but many questions regarding mechanisms and consequences of HRs remain unaddressed.We have summarized the mechanistic roles and cellular events of plant cells during HR in defense regulation. Roles of different genes during HR have been discussed to clarify genetic control of HR in plants. Generally existing ambiguities about HR and programmed cell death at the reader level has been addressed.

中文翻译：

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植物过敏反应与病原体入侵：少数人的死亡赋予了他人生命。

过敏反应（HR）是针对病原体入侵的防御措施。通常，HR可以通过出现死亡的棕色细胞以及可见病变来预测。尽管在HR期间死亡可能仅限于与病原体直接接触的细胞，但细胞死亡也可能从感染部位扩散开来。植物细胞死亡形态的多样性暗示了触发HR的不同途径。人们认为，尽管存在差异，但植物中的HR仍具有类似于动物程序性细胞死亡（PCD）的功能，以限制病原体的进程。实际上，HR至关重要地启动了系统信号，以激活植物远端部位的防御系统，最终导致系统获得性抗性（SAR）。因此，HR可与感染部位的其他局部免疫作用/反应区分开。HR包括一系列事件，包括转录重编程，Ca2 +涌入，氧化爆发和植物激素信号传导。尽管在植物的HR方面已经做了大量工作，但是关于HR的机制和后果的许多问题仍未解决。我们总结了HR在防御调节过程中植物细胞的机械作用和细胞事件。已经讨论了不同基因在HR中的作用，以阐明植物中HR的遗传控制。通常，已经解决了在阅读器级别上有关HR和程序性细胞死亡的现有歧义。尽管在植物的HR方面已经做了大量工作，但是关于HR的机制和后果的许多问题仍未解决。我们总结了HR在防御调节过程中植物细胞的机械作用和细胞事件。已经讨论了不同基因在HR中的作用，以阐明植物中HR的遗传控制。通常，已经解决了在阅读器级别上有关HR和程序性细胞死亡的现有歧义。尽管在植物的HR方面已经做了大量工作，但是关于HR的机制和后果的许多问题仍未解决。我们总结了HR在防御调节过程中植物细胞的机械作用和细胞事件。已经讨论了不同基因在HR中的作用，以阐明植物中HR的遗传控制。通常，已经解决了在阅读器级别上有关HR和程序性细胞死亡的现有歧义。