Maize Plants Chimeric for an Autoactive Resistance Gene Display a Cell-Autonomous Hypersensitive Response but Non-Cell Autonomous Defense Signaling.

The maize gene is a mutant form of the gene that confers resistance to common rust. 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 in four different genetic backgrounds, were identified that had chimeric leaves with lesioned sectors showing HR abutting green nonlesioned sectors lacking HR. The sequence derived from each of the lesioned portions of leaves was unaltered from the expected sequence whereas the sequences from nine of the nonlesioned sectors displayed various mutations, and we were unable to amplify 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 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 . Defense gene expression was somewhat elevated in nonlesioned sectors abutting sectors carrying compared with near-isogenic plants lacking . This suggests that, whereas the HR itself was cell autonomous, other aspects of the defense response initiated by were not.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.