The Arabidopsis Resistance-Like Gene SNC1 Is Activated by Mutations in SRFR1 and Contributes to Resistance to the Bacterial Effector AvrRps4

PLoS Pathogens

Joseph A. Adiasor¹  Ji Chul Nam²  Sang Hee Kim³  Fei Gao³  Saikat Bhattacharjee³  Walter Gassmann³ 

[1] Department of Chemistry, University of Missouri, Columbia, Missouri, United States of America;Division of Biological Sciences, University of Missouri, Columbia, Missouri, United States of America;Division of Plant Sciences, Christopher S. Bond Life Sciences Center and Interdisciplinary Plant Group, University of Missouri, Columbia, Missouri, United States of America

关键词: Genetically modified plants;    Arabidopsis thaliana;    Phenotypes;    Polymerase chain reaction;    Alleles;    Messenger RNA;    Gene expression;    Bacterial growth;   

DOI  :  10.1371/journal.ppat.1001172

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

The SUPPRESSOR OF rps4-RLD1 (SRFR1) gene was identified based on enhanced AvrRps4-triggered resistance in the naturally susceptible Arabidopsis accession RLD. No other phenotypic effects were recorded, and the extent of SRFR1 involvement in regulating effector-triggered immunity was unknown. Here we show that mutations in SRFR1 in the accession Columbia-0 (Col-0) lead to severe stunting and constitutive expression of the defense gene PR1. These phenotypes were temperature-dependent. A cross between srfr1-1 (RLD background) and srfr1-4 (Col-0) showed that stunting was caused by a recessive locus in Col-0. Mapping and targeted crosses identified the Col-0-specific resistance gene SNC1 as the locus that causes stunting. SRFR1 was proposed to function as a transcriptional repressor, and SNC1 is indeed overexpressed in srfr1-4. Interestingly, co-regulated genes in the SNC1 cluster are also upregulated in the srfr1-4 snc1-11 double mutant, indicating that the overexpression of SNC1 is not a secondary effect of constitutive defense activation. In addition, a Col-0 RPS4 mutant showed full susceptibility to bacteria expressing avrRps4 at 24°C but not at 22°C, while RLD susceptibility was not temperature-dependent. The rps4-2 snc1-11 double mutant showed increased, but not full, susceptibility at 22°C, indicating that additional cross-talk between resistance pathways may exist. Intriguingly, when transiently expressed in Nicotiana benthamiana, SRFR1, RPS4 and SNC1 are in a common protein complex in a cytoplasmic microsomal compartment. Our results highlight SRFR1 as a convergence point in at least a subset of TIR-NBS-LRR protein-mediated immunity in Arabidopsis. Based on the cross-talk evident from our results, they also suggest that reports of constitutive resistance phenotypes in Col-0 need to consider the possible involvement of SNC1.

【 授权许可】

CC BY