Race 2 of Verticillium dahliae infecting tomato in Japan can be split into two races with differential pathogenicity on resistant rootstocks. (11th July 2016)

• Record Type: Journal Article
• Authors: Usami, T.; Momma, N.; Kikuchi, S.; Watanabe, H.; Hayashi, A.; Mizukawa, M.; Yoshino, K.; Ohmori, Y.
• Is Part Of: Plant pathology. Volume 66:Number 2(2017)
• Page Start: 230
• Page End: 238
• Publication Date: 2016-07-11
• Subjects: grafting -- new race -- resistant cultivar -- verticillium wilt; Agricultural pests -- Periodicals; Plant diseases -- Periodicals; 632
• DOI: 10.1111/ppa.12576
• Languages: English
• ISSNs: 0032-0862

Abstract

Abstract : Verticillium dahliae infecting tomato can be differentiated into races 1 and 2 based on differential pathogenicity on tomato cultivars carrying resistance gene Ve1 . Although no commercial cultivars resistant to race 2 are available, race 2‐resistant rootstock cultivars Aibou and Ganbarune‐Karis have been bred in Japan. Nevertheless, the resistance of these rootstocks appears to be unstable in commercial tomato fields. Pathogenicity assays conducted under controlled conditions revealed that these rootstock cultivars are resistant to some isolates of race 2; this resistance is controlled by a single dominant locus, denoted by V2, based on segregation of resistance in F2 populations from selfed rootstock cultivars. However, some other isolates of race 2 can overcome this resistance. Therefore it is proposed that the current race 2 of V. dahliae should be divided into two races, i.e. 'race 2' (nonpathogenic on Aibou) and 'race 3' (pathogenic on Aibou). The distribution of these races was surveyed in 70 commercial tomato fields in Hida, Gifu Prefecture, Japan. Race 3 was found in 45 fields, indicating that race 3 had already spread throughout the region. On the other hand, 25 fields had only race 2, and thus race 2‐resistant rootstocks would be effective for disease management in these fields. Races 2 and 3 could not be identified by genomic Southern hybridization probed with a telomere sequence, nor with previously reported race‐specific PCR assays. Elucidation of race‐determining mechanisms and development of methods for quick race identification should be made in future studies.