Biological and Molecular Characterization of Fusarium oxysporum f. sp. lycopersici Divides Race 1 Isolates into Separate Virulence Groups

Abstract

A collection of race 1 and race 2 isolates of Fusarium oxysporum f. sp. lycopersici was screened for vegetative compatibility and characterized by random amplified polymorphic DNA (RAPD) analysis to establish the identity and genetic diversity of the isolates. Comparison of RAPD profiles revealed two main groups that coincide with vegetative compatibility groups (VCGs). In addition, several single-member VCGs were identified that could not be grouped in one of the two main RAPD clusters. This suggests that F. oxysporum f. sp. lycopersici is a polyphyletic taxon. To assign avirulence genotypes to race 1 isolates, they were tested for their virulence on a small set of tomato lines (Lycopersicon esculentum), including line OT364. This line was selected because it shows resistance to race 2 isolates but, unlike most other race 2-resistant lines, susceptibility to race 1 isolates. To exclude the influence of other components than those related to the race-specific resistance response, we tested the virulence of race 1 isolates on a susceptible tomato that has become race 2 resistant by introduction of an I-2 transgene. The results show that both line OT364 and the transgenic line were significantly affected by four race 1 isolates, but not by seven other race 1 isolates nor by any race 2 isolates. This allowed a subdivision of race 1 isolates based on the presence or absence of an avirulence gene corresponding to the I-2 resistance gene. The data presented here support a gene-for-gene relationship for the interaction between F. oxysporum f. sp. lycopersici and its host tomato.

The role of phospholipase D in plant stress responses

“…lycopersici isolates Fol004, Fol007 and Fol029 were used for bioassays on the LePLDβ1-silenced and isogenic wildtype tomato plant lines. The assays were performed as described previously (Mes et al, 1999). Briefly, ten-day-old seedlings were inoculated by dipping the roots in a conidial suspension and grown for 3 weeks after which fresh weight of plants cut just above the cotyledons was determined.…”

Expression of effector gene SIX1 of Fusarium oxysporum requires living plant cells

“…lycopersici (Fol) isolate Fol007, described in Mes et al (1999) was used to inoculate minimal growth medium (3% sucrose, 1% KNO 3 and 0.17% yeast nitrogen base without amino acids and ammonia). After 5 days of growth (25°C, 175 rpm), microconidia were isolated and used to inoculate the test medium (25 ml with 5 Â 10 8 microconidia).…”

“…Ten-day-old tomato seedlings were inoculated via the root dip method (Mes et al, 1999;Wellman, 1939). Spores were isolated from 5-day-old potato dextrose broth (PDB) cultures (Difco) or 3-to 5-day-old cultures in minimal medium (1% KNO 3 , 3% sucrose and 0.17% Yeast Nitrogen Base without amino acids or ammonia).…”

Simple Mass-screening Methods for Resistance of Tomato to Fusarium oxysporum f. sp. lycopersici

“…The infected plants were incubated in humidity chamber at 25 and 30℃ for 24 h and then transferred to a growth room at 25 and 30℃, respectively with 12-h light a day. After 4 weeks, disease severity of the seedlings was investigated on a scale of 0-5. root dip 방법이 주로 사용되고 있다 (Bost, 2001;Bournival et al, 1989;Davis et al, 1988;Grattidge and O' Brien, 1982;Huang and Lindhout, 1997;Park et al, 2012 (Bournival et al, 1989;El Mohtar et al, 2007;Huang and Lindhout, 1997;Mes et al, 1999). z Seeds of tomato cultivar were sown in 6 × 12 plastic cell tray and grown in a green house at 25 ± 5℃.…”