title: A new biotype of Fusarium oxysporum f. sp. lycopersici race 2 emerged by a transposon-driven mutation of avirulence gene AVR1.
abstract: Emergence of races in Fusarium oxysporum f. sp. lycopersici (Fol) is caused by loss or mutation of at least one avirulence (AVR) gene. The product of AVR1 is a small protein (Avr1) secreted by Fol in tomato xylem sap during infection. This protein triggers Fol race 1 specific resistance (I) in tomato, indicating that AVR1 is an AVR gene. Deletion of AVR1 in race 1 resulted in the emergence of race 2, and an additional mutation in AVR2 generated race 3. Previously, we reported a new biotype of race 3, KoChi-1, in which AVR1 was truncated by a transposon Hormin, which suggested a new route to evolution of races in Fol However, to date no race 2 isolate carrying Hormin-truncated AVR1 has been reported. In this report, we describe such isolates, represented by Chiba-5, in which Hormin insertion occurred in AVR1 at a position different from that in KoChi-1. AVR1 truncation in both isolates resulted in production of defective Avr1 proteins. Chiba-5 and KoChi-1 belong to different phylogenetic clades, A1 and A2, respectively, suggesting that insertion of Hormin in AVR1 in Chiba-5 and KoChi-1 occurred as independent evolutionary events.
authors.affiliation: Graduate School of Agriculture, Tokyo University of Agriculture and Technology (TUAT), Fuchu, Tokyo 183-8509, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kashiwa
authors.affiliation: Chiba Prefectural Agriculture and Forestry Research Center, 808 Daizenno-cho, Midori-ku, Chiba 266-0006, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Suzuki
authors.affiliation: Graduate School of Agriculture, Tokyo University of Agriculture and Technology (TUAT), Fuchu, Tokyo 183-8509, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Sato
authors.affiliation: Graduate School of Agriculture, Tokyo University of Agriculture and Technology (TUAT), Fuchu, Tokyo 183-8509, Japan.
authors.forename: Kotaro
authors.initials: K
authors.lastname: Akai
authors.affiliation: Graduate School of Agriculture, Tokyo University of Agriculture and Technology (TUAT), Fuchu, Tokyo 183-8509, Japan.
authors.forename: Tohru
authors.initials: T
authors.lastname: Teraoka
authors.affiliation: Graduate School of Agriculture, Tokyo University of Agriculture and Technology (TUAT), Fuchu, Tokyo 183-8509, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Komatsu
authors.affiliation: Graduate School of Agriculture, Tokyo University of Agriculture and Technology (TUAT), Fuchu, Tokyo 183-8509, Japan arie@cc.tuat.ac.jp.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Arie
mesh_terms: D002874:Chromosome Mapping; D015825:Chromosomes, Fungal; D004251:DNA Transposable Elements; D060467:Disease Resistance; D005670:Fusarium / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity; D005816:Genetic Complementation Test; D016681:Genome, Fungal; D018551:Solanum lycopersicum / Q000382:microbiology; D016254:Mutagenesis, Insertional; D009154:Mutation; D010802:Phylogeny; D010935:Plant Diseases / Q000382:microbiology; D014774:Virulence / Q000235:genetics
chemical_list: D004251:DNA Transposable Elements
keywords: Fusarium oxysporum; avirulence gene; gene-for-gene theory; pathogenicity chromosome; race differentiation; tomato