Maize plants chimeric for an autoactive resistance gene display a cell autonomous hypersensitive response but non-cell autonomous defense signaling

Authors: KARRE, SHAILESH - North Carolina State University; KIM, BONG-SUK - Purdue University; KIM, SAET-BYUL - North Carolina State University; DILKES, BRIAN - Purdue University; JOHAL, GURI - Purdue University; Balint-Kurti, Peter

Submitted to: Molecular Plant-Microbe Interactions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/20/2021
Publication Date: 1/25/2021
Citation: Karre, S., Kim, B., Kim, S., Dilkes, B., Johal, G., Balint Kurti, P.J. 2021. Maize plants chimeric for an autoactive resistance gene display a cell autonomous hypersensitive response but non-cell autonomous defense signaling. Molecular Plant-Microbe Interactions. https://doi.org/10.1094/MPMI-04-20-0091-R.
DOI: https://doi.org/10.1094/MPMI-04-20-0091-R

Interpretive Summary: We have generated plants with chimeric leaves- part of the leaf has a gene that causes a constant defense response and part of it doesn’t. We show that some aspects of the defense response are specific to the part with the constant-defense response gene while other aspects are observed in both parts of the leaf.

Technical Abstract: The maize gene Rp1-D21 is a mutant form of the gene Rp1-D that confers resistance to common smut. 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). Six plants in three different genetic backgrounds heterozygous for Rp1-D21 were identified that had leaves with lesioned sectors showing HR abutting green non-lesioned sectors lacking HR. The Rp1-D21 sequence derived from each of the lesioned sectors was unaltered from the expected sequence whereas the Rp1-D21 sequences from the non-lesioned sectors displayed various mutations. 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 non-lesioned sectors as well as in near-isogenic plants lacking and carrying Rp1-D21. Defense gene expression was somewhat elevated in non-lesioned sectors abutting sectors carrying Rp1-D21 compared to near-isogenic plants lacking Rp1-D21. This suggests that while the HR itself was cell autonomous, other aspects of the defense response initiated by Rp1-D21 were not.