Arabidopsis SGT1b is required for defense signaling conferred by several downy mildew resistance genes.
We describe the identification of a mutant in the Arabidopsis accession Columbia (Col-0) that exhibits enhanced downy mildew (edm1) susceptibility to several Peronospora parasitica isolates, including the RPP7-diagnostic isolate Hiks1. The mutation was mapped to chromosome IV and characterized physically as a 35-kb deletion spanning seven genes. One of these genes complemented the mutant to full wild-type resistance against all of the Peronospora isolates tested. This gene (AtSGT1b) encodes a predicted protein of 39.8 kD and is an Arabidopsis ortholog of yeast SGT1, which was described originally as a key regulatory protein in centromere function and ubiquitin-mediated proteolysis. AtSGT1b contains three tetratricopeptide repeats at the N terminus followed by a bipartite chord-containing SGT domain and an SGT-specific domain at the C terminus. We discuss the role of AtSGT1b in disease resistance and its possible involvement in ubiquitin-mediated proteolysis in plants.
Tör
Mahmut
M
Plant Genetics and Biotechnology Department, Horticulture Research International, Wellesbourne, Warwick CV35 9EF, United Kingdom.
Gordon
Pam
P
Cuzick
Alayne
A
Eulgem
Thomas
T
Sinapidou
Evaggelia
E
Mert-Türk
Figen
F
Can
Canan
C
Dangl
Jeffery L
JL
Holub
Eric B
EB
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics*; D018797:Cell Cycle Proteins / Q000235:genetics*; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D018548:Cotyledon / Q000235:genetics / Q000254:growth & development / Q000382:microbiology; D005658:Fungi / Q000254:growth & development; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D007113:Immunity, Innate / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology*; D030821:Plants, Genetically Modified; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000235:genetics*; D015003:Yeasts / Q000235:genetics / Q000254:growth & development
D029681:Arabidopsis Proteins; D018797:Cell Cycle Proteins; C452192:SGT1b protein, Arabidopsis