title: Characterization of a vacuolar processing enzyme expressed in Arachis diogoi in resistance responses against late leaf spot pathogen, Phaeoisariopsis personata.
abstract: Vacuolar processing enzymes are cysteine proteases responsible for maturation of vacuolar proteins. They have been shown to possess caspase-1-like activity, mediate cell death and display increased activity during pathogen infections. A transcript derived fragment corresponding to VPE was found to be up-regulated in a cDNA-AFLP analysis of host responses of a wild peanut, Arachis diogoi upon challenge from the late leaf spot pathogen Phaeoisariopsis personata, which was subsequently validated by q-PCR in a time course analysis, where susceptible peanut did not show its upregulation. In transient conditional and constitutive expression studies in tobacco leaves using agroinfiltration, we have observed that expression of AdVPE was associated with hypersensitive response (HR) like cell death. AdVPE expression was found to be high at 24 h post estradiol application and this was associated with the enhanced co-expression of molecular markers of HR cell death genes and genes for pathogenesis related proteins indicating that AdVPE positively regulates defense responses and its estradiol induced expression is sufficient for HR-like cell death in tobacco. We found that AdVPE expression was very strongly induced in response to sodium nitroprusside, which indicates its involvement in stress signaling. Induced expression of AdVPE in response to jasmonic acid and ethylene also indicates its involvement in an interconnected network of signaling. Transgenic tobacco plants ectopically expressing AdVPE exhibited enhanced resistance against Phytophthora parasitica var. nicotianae, Alternaria alternata var.  nicotianae and Rhizoctonia solani. To our knowledge, this is the first report on the heterologous expression of a pathogen induced VPE enhancing resistance to fungal pathogens with cell death phenomenon under transient expression.
authors.affiliation: Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India, dilip.hcu@gmail.com.
authors.forename: Dilip
authors.initials: D
authors.lastname: Kumar
authors.forename: Sakshi
authors.initials: S
authors.lastname: Rampuria
authors.forename: Naveen Kumar
authors.initials: NK
authors.lastname: Singh
authors.forename: Pawan
authors.initials: P
authors.lastname: Shukla
authors.forename: P B
authors.initials: PB
authors.lastname: Kirti
mesh_terms: D054458:Amplified Fragment Length Polymorphism Analysis; D010367:Arachis / Q000201:enzymology* / Q000276:immunology / Q000382:microbiology; D001203:Ascomycota / Q000502:physiology*; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D018076:DNA, Complementary / Q000235:genetics / Q000302:isolation & purification; D060467:Disease Resistance / Q000276:immunology*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D010802:Phylogeny; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology*; D018515:Plant Leaves / Q000276:immunology / Q000382:microbiology*; D030821:Plants, Genetically Modified; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D013312:Stress, Physiological / Q000235:genetics; D014026:Nicotiana / Q000235:genetics
chemical_list: D018076:DNA, Complementary; D012333:RNA, Messenger; D003546:Cysteine Endopeptidases; C089278:vacuolar processing enzyme