title: The pearl millet mitogen-activated protein kinase PgMPK4 is involved in responses to downy mildew infection and in jasmonic- and salicylic acid-mediated defense.
abstract: Plant mitogen-activated protein kinases (MPKs) transduce signals required for the induction of immunity triggered by host recognition of pathogen-associated molecular patterns. We isolated a full-length cDNA of a group B MPK (PgMPK4) from pearl millet. Autophosphorylation assay of recombinant PgMPK4 produced in Escherichia coli confirmed it as a kinase. Differential accumulation of PgMPK4 mRNA and kinase activity was observed between pearl millet cultivars 852B and IP18292 in response to inoculation with the downy mildew oomycete pathogen Sclerospora graminicola. This increased accumulation of PgMPK4 mRNA, kinase activity as well as nuclear-localization of PgMPK protein(s) was only detected in the S. graminicola resistant cultivar IP18292 with a ~tenfold peak at 9 h post inoculation. In the susceptible cultivar 852B, PgMPK4 mRNA and immuno-detectable nuclear PgMPK could be induced by application of the chemical elicitor β-amino butyric acid, the non-pathogenic bacteria Pseudomonas fluorescens, or by the phytohormones jasmonic acid (JA) or salicylic acid (SA). Furthermore, kinase inhibitor treatments indicated that PgMPK4 is involved in the JA- and SA-mediated expression of three defense genes, lipoxygenase, catalase 3 and polygalacturonase-inhibitor protein. These findings indicate that PgMPK/s contribute to pearl millet defense against the downy mildew pathogen by activating the expression of defense proteins.
authors.affiliation: Department of Studies in Biotechnology, Manasagangotri, University of Mysore, Mysore, 570 006, Karnataka, India.
authors.forename: Prasad
authors.initials: P
authors.lastname: Melvin
authors.forename: S Ashok
authors.initials: SA
authors.lastname: Prabhu
authors.forename: Mariswamy
authors.initials: M
authors.lastname: Veena
authors.forename: Sekhar
authors.initials: S
authors.lastname: Shailasree
authors.forename: Morten
authors.initials: M
authors.lastname: Petersen
authors.forename: John
authors.initials: J
authors.lastname: Mundy
authors.forename: Shekar H
authors.initials: SH
authors.lastname: Shetty
authors.forename: K Ramachandra
authors.initials: KR
authors.lastname: Kini
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D003517:Cyclopentanes / Q000378:metabolism; D018744:DNA, Plant / Q000235:genetics; D060467:Disease Resistance / Q000235:genetics / Q000502:physiology; D017343:Genes, Plant; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009868:Oomycetes / Q000472:pathogenicity; D054883:Oxylipins / Q000378:metabolism; D031782:Pennisetum / Q000201:enzymology* / Q000235:genetics / Q000382:microbiology; D010802:Phylogeny; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D020156:Salicylic Acid / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
chemical_list: D003517:Cyclopentanes; D018744:DNA, Plant; D054883:Oxylipins; D010940:Plant Proteins; D012333:RNA, Messenger; D018749:RNA, Plant; D011994:Recombinant Proteins; C011006:jasmonic acid; D020928:Mitogen-Activated Protein Kinases; D020156:Salicylic Acid