The maize gene Rp1-D21 is a mutant form of the gene Rp1-D that confers resistance to common rust. Rp1-D21 triggers a spontaneous defense response that occurs in the absence of the pathogen and includes a programed cell death called the hypersensitive response (HR). Eleven plants heterozygous for Rp1-D21, in four different genetic backgrounds, were identified that had chimeric leaves with lesioned sectors showing HR abutting green nonlesioned sectors lacking HR. The Rp1-D21 sequence derived from each of the lesioned portions of leaves was unaltered from the expected sequence whereas the Rp1-D21 sequences from nine of the nonlesioned sectors displayed various mutations, and we were unable to amplify Rp1-D21 from the other two nonlesioned sectors. In every case, the borders between the sectors were sharp, with no transition zone, suggesting that HR and chlorosis associated with Rp1-D21 activity was cell autonomous. Expression of defense response marker genes was assessed in the lesioned and nonlesioned sectors as well as in near-isogenic plants lacking and carrying Rp1-D21. Defense gene expression was somewhat elevated in nonlesioned sectors abutting sectors carrying Rp1-D21 compared with near-isogenic plants lacking Rp1-D21. This suggests that, whereas the HR itself was cell autonomous, other aspects of the defense response initiated by Rp1-D21 were not.

Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

玉米基因Rp1-D21是基因Rp1-D的突变形式，赋予对普通锈病的抗性。Rp1-D21触发自发防御反应，该反应在病原体不存在的情况下发生，包括称为过敏反应 (HR) 的程序性细胞死亡。在四种不同的遗传背景中，鉴定出11 株Rp1-D21杂合植物，它们具有嵌合叶，其中受损扇区显示 HR 与缺乏 HR 的绿色非受损扇区相邻。来自每个叶片受损部分的Rp1-D21序列与预期序列没有改变，而Rp1-D21来自九个未受损扇区的序列显示出各种突变，我们无法从其他两个未受损扇区扩增Rp1-D21。在每种情况下，扇区之间的边界都很清晰，没有过渡区，这表明与Rp1-D21活动相关的 HR 和萎黄病是细胞自主的。防御反应标记基因的表达在受损和未受损部分以及缺乏和携带Rp1-D21 的近等基因植物中进行评估。与缺乏Rp1-D21 的近等基因植物相比，与携带Rp1-D21 的扇区相邻的非损伤扇区的防御基因表达有所升高. 这表明，虽然 HR 本身是细胞自主的，但由Rp1-D21发起的防御反应的其他方面不是。

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