title: Cytokinin Production by the Rice Blast Fungus Is a Pivotal Requirement for Full Virulence.
abstract: Plants produce cytokinin (CK) hormones for controlling key developmental processes like source/sink distribution, cell division or programmed cell-death. Some plant pathogens have been shown to produce CKs but the function of this mimicry production by non-tumor inducing pathogens, has yet to be established. Here we identify a gene required for CK biosynthesis, CKS1, in the rice blast fungus Magnaporthe oryzae. The fungal-secreted CKs are likely perceived by the plant during infection since the transcriptional regulation of rice CK-responsive genes is altered in plants infected by the mutants in which CKS1 gene was deleted. Although cks1 mutants showed normal in vitro growth and development, they were severely affected for in planta growth and virulence. Moreover, we showed that the cks1 mutant triggered enhanced induction of plant defenses as manifested by an elevated oxidative burst and expression of defense-related markers. In addition, the contents of sugars and key amino acids for fungal growth were altered in and around the infection site by the cks1 mutant in a different manner than by the control strain. These results suggest that fungal-derived CKs are key effectors required for dampening host defenses and affecting sugar and amino acid distribution in and around the infection site.
authors.affiliation: Université Montpellier, UMR BGPI INRA/CIRAD/SupAgro, Montpellier, France.
authors.forename: Emilie
authors.initials: E
authors.lastname: Chanclud
authors.affiliation: Biology Department, Trent University, Peterborough, Ontario, Canada.|Department of Plant Genetics, Physiology and Biotechnology, University of Technology and Life Sciences, Bydgoszcz, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Kisiala
authors.affiliation: Biology Department, Trent University, Peterborough, Ontario, Canada.
authors.forename: Neil R J
authors.initials: NR
authors.lastname: Emery
authors.affiliation: INRA, UMR BGPI INRA/CIRAD/SupAgro, Montpellier, France.
authors.forename: Véronique
authors.initials: V
authors.lastname: Chalvon
authors.affiliation: INRA, UMR BGPI INRA/CIRAD/SupAgro, Montpellier, France.
authors.forename: Aurélie
authors.initials: A
authors.lastname: Ducasse
authors.affiliation: INRA, UMR BGPI INRA/CIRAD/SupAgro, Montpellier, France.
authors.forename: Corinne
authors.initials: C
authors.lastname: Romiti-Michel
authors.affiliation: Université Rennes 1, UMR1349 IGEPP, Rennes, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Gravot
authors.affiliation: INRA, UMR BGPI INRA/CIRAD/SupAgro, Montpellier, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Kroj
authors.affiliation: INRA, UMR BGPI INRA/CIRAD/SupAgro, Montpellier, France.
authors.forename: Jean-Benoit
authors.initials: JB
authors.lastname: Morel
mesh_terms: D003583:Cytokinins / Q000096:biosynthesis / Q000235:genetics*; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D005800:Genes, Fungal / Q000235:genetics*; D020082:Magnaporthe / Q000235:genetics; D012275:Oryza / Q000382:microbiology*; D010935:Plant Diseases / Q000382:microbiology; D018515:Plant Leaves / Q000382:microbiology; D014774:Virulence / Q000235:genetics*
chemical_list: D003583:Cytokinins