Different domains of Phytophthora sojae effector Avr4/6 are recognized by soybean resistance genes Rps4 and Rps6.
At least 12 avirulence genes have been genetically identified and mapped in Phytophthora sojae, an oomycete pathogen causing root and stem rot of soybean. Previously, the Avr4 and Avr6 genes of P. sojae were genetically mapped within a 24 kb interval of the genome. Here, we identify Avr4 and Avr6 and show that they are actually a single gene, Avr4/6, located near the 24-kb region. Avr4/6 encodes a secreted protein of 123 amino acids with an RXLR-dEER protein translocation motif. Transient expression of Avr4/6 in soybean leaves revealed that its gene product could trigger a hypersensitive response (HR) in the presence of either Rps4 or Rps6. Silencing Avr4/6 in P. sojae stable transformants abolished the avirulence phenotype exhibited on both Rps4 and Rps6 soybean cultivars. The N terminus of Avr4/6, including the dEER motif, is sufficient to trigger Rps4-dependent HR while its C terminus is sufficient to trigger Rps6-mediated HR. Compared with alleles from avirulent races, alleles of Avr4/6 from virulent races possess nucleotide substitutions in the 5' untranslated region of the gene but not in the protein-coding region.
Dou
Daolong
D
Virginia Bioinformatics Institute, Virginia Polytechnic Institute and State University Blacksburg 24061, USA.
Kale
Shiv D
SD
Liu
Tingli
T
Tang
Qinghua
Q
Wang
Xia
X
Arredondo
Felipe D
FD
Basnayake
Shiromi
S
Whisson
Stephen
S
Drenth
Andre
A
Maclean
Don
D
Tyler
Brett M
BM
D000483:Alleles; D001483:Base Sequence; D016923:Cell Death; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D008969:Molecular Sequence Data; D010838:Phytophthora / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D010935:Plant Diseases / Q000235:genetics* / Q000382:microbiology*; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism*; D011110:Polymorphism, Genetic; D013025:Glycine max / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D014774:Virulence
D010940:Plant Proteins