NPS6, encoding a nonribosomal peptide synthetase involved in siderophore-mediated iron metabolism, is a conserved virulence determinant of plant pathogenic ascomycetes.
NPS6, encoding a nonribosomal peptide synthetase, is a virulence determinant in the maize (Zea mays) pathogen Cochliobolus heterostrophus and is involved in tolerance to H(2)O(2). Deletion of NPS6 orthologs in the rice (Oryza sativa) pathogen, Cochliobolus miyabeanus, the wheat (Triticum aestivum) pathogen, Fusarium graminearum, and the Arabidopsis thaliana pathogen, Alternaria brassicicola, resulted in reduced virulence and hypersensitivity to H(2)O(2). Introduction of the NPS6 ortholog from the saprobe Neurospora crassa to the Deltanps6 strain of C. heterostrophus restored wild-type virulence to maize and tolerance to H(2)O(2), demonstrating functional conservation in filamentous ascomycete phytopathogens and saprobes. Increased sensitivity to iron depletion was identified as a conserved phenotype of Deltanps6 strains. Exogenous application of iron enhanced the virulence of Deltanps6 strains of C. heterostrophus, C. miyabeanus, F. graminearum, and A. brassicicola to each host. NPS6 is responsible for the biosynthesis of extracellular siderophores by C. heterostrophus, F. graminearum, and A. brassicicola. Application of the extracellular siderophore of A. brassicicola restored wild-type virulence of the DeltaAbnps6 strain to Arabidopsis. It is proposed that the role of extracellular siderophores in fungal virulence to plants is to supply an essential nutrient, iron, to their producers in planta and not to act as phytotoxins, depriving their hosts of iron.
Oide
Shinichi
S
Department of Plant Pathology, Cornell University, Ithaca, New York 14853, USA.
Moeder
Wolfgang
W
Krasnoff
Stuart
S
Gibson
Donna
D
Haas
Hubertus
H
Yoshioka
Keiko
K
Turgeon
B Gillian
BG
D001203:Ascomycota / Q000201:enzymology* / Q000472:pathogenicity; D001483:Base Sequence; D017124:Conserved Sequence; D017931:DNA Primers; D007501:Iron / Q000378:metabolism*; D008969:Molecular Sequence Data; D018384:Oxidative Stress; D010453:Peptide Synthases / Q000737:chemistry / Q000378:metabolism*; D010944:Plants / Q000382:microbiology*; D017262:Siderophores / Q000096:biosynthesis / Q000378:metabolism*; D014774:Virulence
D017931:DNA Primers; D017262:Siderophores; D007501:Iron; D010453:Peptide Synthases