Arabidopsis ssi2-conferred susceptibility to Botrytis cinerea is dependent on EDS5 and PAD4.
Loss of a stearoyl-ACP desaturase activity in the Arabidopsis thaliana ssi2 mutant confers susceptibility to the necrotroph, Botrytis cinerea. In contrast, the ssi2 mutant exhibits enhanced resistance to Pseudomonas syringae, Peronospora parasitica, and Cucumber mosaic virus. The altered basal resistance to these pathogens in the ssi2 mutant plant is accompanied by the constitutive accumulation of elevated salicylic acid (SA) level and expression of the pathogenesis-related 1 (PR1) gene, the inability of jasmonic acid (JA) to activate expression of the defensin gene, PDF1.2, and the spontaneous death of cells. Here, we show that presence of the eds5 and pad4 mutant alleles compromises the ssi2-conferred resistance to Pseudomonas syringae pv. maculicola. In contrast, resistance to B. cinerea was restored in the ssi2 eds5 and ssi2 pad4 double-mutant plants. However, resistance to B. cinerea was not accompanied by the restoration of JA responsiveness in the ssi2 eds5 and ssi2 pad4 plants. The ssi2 eds5 and ssi2 pad4 plants retain the ssi2-conferred spontaneous cell death phenotype, suggesting that cell death is not a major factor that predisposes the ssi2 mutant to infection by B. cinerea. Furthermore, the high SA content of the ssi2 pad4 plant, combined with our previous observation that the SA-deficient ssi2 nahG plant succumbs to infection by B. cinerea, suggests that elevated SA level does not have a causal role in the ssi2-conferred susceptibility to B. cinerea. Our results suggest that interaction between an SSI2-dependent factor or factors and an EDS5- and PAD4-dependent mechanism or mechanisms modulates defense to B. cinerea.
Nandi
Ashis
A
Division of Biology, Cellular and Developmental Biology Program, Kansas State University, Manhattan 66506, USA.
Moeder
Wolfgang
W
Kachroo
Pradeep
P
Klessig
Daniel F
DF
Shah
Jyoti
J
D017360:Arabidopsis / Q000235:genetics* / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics*; D020171:Botrytis / Q000472:pathogenicity*; D002265:Carboxylic Ester Hydrolases / Q000235:genetics*; D016923:Cell Death; D003517:Cyclopentanes / Q000378:metabolism; D044943:Fatty Acid Desaturases / Q000235:genetics*; D018506:Gene Expression Regulation, Plant; D026901:Membrane Transport Proteins / Q000235:genetics*; D054883:Oxylipins; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D044224:Pseudomonas syringae / Q000472:pathogenicity; D020156:Salicylic Acid / Q000378:metabolism
D029681:Arabidopsis Proteins; D003517:Cyclopentanes; C455514:EDS5 protein, Arabidopsis; D026901:Membrane Transport Proteins; D054883:Oxylipins; C011006:jasmonic acid; D044943:Fatty Acid Desaturases; C433487:stearoyl ACP desaturase, Arabidopsis; D002265:Carboxylic Ester Hydrolases; C400766:PAD4 protein, Arabidopsis; D020156:Salicylic Acid