title: Novel Mutations Detected in Avirulence Genes Overcoming Tomato Cf Resistance Genes in Isolates of a Japanese Population of Cladosporium fulvum.
abstract: Leaf mold of tomato is caused by the biotrophic fungus Cladosporium fulvum which complies with the gene-for-gene system. The disease was first reported in Japan in the 1920s and has since been frequently observed. Initially only race 0 isolates were reported, but since the consecutive introduction of resistance genes Cf-2, Cf-4, Cf-5 and Cf-9 new races have evolved. Here we first determined the virulence spectrum of 133 C. fulvum isolates collected from 22 prefectures in Japan, and subsequently sequenced the avirulence (Avr) genes Avr2, Avr4, Avr4E, Avr5 and Avr9 to determine the molecular basis of overcoming Cf genes. Twelve races of C. fulvum with a different virulence spectrum were identified, of which races 9, 2.9, 4.9, 4.5.9 and 4.9.11 occur only in Japan. The Avr genes in many of these races contain unique mutations not observed in races identified elsewhere in the world including (i) frameshift mutations and (ii) transposon insertions in Avr2, (iii) point mutations in Avr4 and Avr4E, and (iv) deletions of Avr4E, Avr5 and Avr9. New races have developed by selection pressure imposed by consecutive introductions of Cf-2, Cf-4, Cf-5 and Cf-9 genes in commercially grown tomato cultivars. Our study shows that molecular variations to adapt to different Cf genes in an isolated C. fulvum population in Japan are novel but overall follow similar patterns as those observed in populations from other parts of the world. Implications for breeding of more durable C. fulvum resistant varieties are discussed.
authors.affiliation: National Agriculture and Food Research Organization, Tsu, Mie, Japan; Wageningen University, Laboratory of Phytopathology, Wageningen, The Netherlands.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Iida
authors.affiliation: Wageningen University, Laboratory of Phytopathology, Wageningen, The Netherlands.
authors.forename: Pieter
authors.initials: P
authors.lastname: van 't Hof
authors.affiliation: Wageningen University, Laboratory of Phytopathology, Wageningen, The Netherlands.
authors.forename: Henriek
authors.initials: H
authors.lastname: Beenen
authors.affiliation: Wageningen University, Laboratory of Phytopathology, Wageningen, The Netherlands.
authors.forename: Carl
authors.initials: C
authors.lastname: Mesarich
authors.affiliation: National Agriculture and Food Research Organization, Tsu, Mie, Japan.
authors.forename: Masaharu
authors.initials: M
authors.lastname: Kubota
authors.affiliation: Wageningen University, Laboratory of Phytopathology, Wageningen, The Netherlands.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Stergiopoulos
authors.affiliation: Wageningen University, Laboratory of Phytopathology, Wageningen, The Netherlands; Seed and Plant Improvement Institute, Karaj, Iran.
authors.forename: Rahim
authors.initials: R
authors.lastname: Mehrabi
authors.affiliation: Hokkaido Research Organization, Ornamental Plants and Vegetables Research Center, Hokkaido, Japan.
authors.forename: Ayumi
authors.initials: A
authors.lastname: Notsu
authors.affiliation: National Agriculture and Food Research Organization, Tsu, Mie, Japan.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Fujiwara
authors.affiliation: King Saud University, College of Science, Botany and Microbiology Department, Riyadh, Saudi Arabia.
authors.forename: Ali
authors.initials: A
authors.lastname: Bahkali
authors.affiliation: King Saud University, College of Science, Botany and Microbiology Department, Riyadh, Saudi Arabia; Plant Pathology Research Institute, Agricultural Research Center, Giza, Egypt.
authors.forename: Kamel
authors.initials: K
authors.lastname: Abd-Elsalam
authors.affiliation: Wageningen University, Laboratory of Phytopathology, Wageningen, The Netherlands.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Collemare
authors.affiliation: Wageningen University, Laboratory of Phytopathology, Wageningen, The Netherlands; Centre for Biosystems Genomics, Wageningen, The Netherlands.
authors.forename: Pierre J G M
authors.initials: PJ
authors.lastname: de Wit
mesh_terms: D002963:Cladosporium / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology* / Q000821:virology; D005656:Fungal Proteins / Q000096:biosynthesis / Q000235:genetics; D005800:Genes, Fungal / Q000235:genetics*; D017343:Genes, Plant / Q000235:genetics*; D005838:Genotype; D054884:Host-Pathogen Interactions / Q000235:genetics*; D007564:Japan; D018551:Solanum lycopersicum / Q000235:genetics / Q000276:immunology / Q000382:microbiology*; D009154:Mutation; D010935:Plant Diseases / Q000382:microbiology*
chemical_list: D005656:Fungal Proteins