Negative regulation of systemic acquired resistance by replication factor C subunit3 in Arabidopsis.
Systemic acquired resistance (SAR) is a plant immune response induced by local necrotizing pathogen infections. Expression of SAR in Arabidopsis (Arabidopsis thaliana) plants correlates with accumulation of salicylic acid (SA) and up-regulation of Pathogenesis-Related (PR) genes. SA is an essential and sufficient signal for SAR. In a genetic screen to search for negative regulators of PR gene expression and SAR, we found a new mutant that is hypersensitive to SA and exhibits enhanced induction of PR genes and resistance against the virulent oomycete Hyaloperonospora arabidopsidis Noco2. The enhanced pathogen resistance in the mutant is Nonexpressor of PR genes1 independent. The mutant gene was identified by map-based cloning, and it encodes a protein with high homology to Replication Factor C Subunit3 (RFC3) of yeast and other eukaryotes; thus, the mutant was named rfc3-1. rfc3-1 mutant plants are smaller than wild-type plants and have narrower leaves and petals. On the epidermis of true leaves, there are fewer cells in rfc3-1 compared with the wild type. Cell production rate is reduced in rfc3-1 mutant roots, indicating that the mutated RFC3 slows down cell proliferation. As Replication Factor C is involved in replication-coupled chromatin assembly, our data suggest that chromatin assembly and remodeling may play important roles in the negative control of PR gene expression and SAR.
Xia
Shitou
S
Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
Zhu
Zhaohai
Z
Hao
Lin
L
Chen
Jin-Gui
JG
Xiao
Langtao
L
Zhang
Yuelin
Y
Li
Xin
X
D000483:Alleles; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000276:immunology*; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D032461:Chromosomes, Plant / Q000235:genetics; D003001:Cloning, Molecular; D004261:DNA Replication / Q000187:drug effects; D007113:Immunity, Innate / Q000187:drug effects / Q000276:immunology*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D020161:Physical Chromosome Mapping; D010935:Plant Diseases / Q000276:immunology*; D018517:Plant Roots / Q000166:cytology / Q000187:drug effects / Q000254:growth & development; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism*; D021381:Protein Transport / Q000187:drug effects; D051818:Replication Protein C / Q000737:chemistry / Q000378:metabolism*; D020156:Salicylic Acid / Q000494:pharmacology; D016415:Sequence Alignment
D021122:Protein Subunits; D051818:Replication Protein C; D020156:Salicylic Acid