Incidence of Fusarium oxysporum f. sp. lycopersici Races in Tomato in Sinaloa, Mexico

Abstract

Sinaloa State is the main producer of tomatoes (Solanum lycopersicum L) in Mexico where production attained 15,784 ha in 2008 (3). Fusarium wilt of tomato caused by Fusarium oxysporum f. sp. lycopersici (Sacc) Snyder & Hansen causes significant yield losses in Sinaloa each year (2). Three pathotypes or races of F. oxysporum f. sp. lycopersici have been described: races 1, 2, and 3 (1). The purpose of this study was to determine the races of F. oxysporum f. sp. lycopersici present in Sinaloa and distribution of these races in the region. F. oxysporum f. sp. lycopersici isolates were obtained from plants showing symptoms of yellowing and necrosis of vascular bundles. Plants were sampled from 50 fields throughout the production area in Sinaloa from November 2008 to March 2009. Four differential cultivars were used to identify the races of 26 F. oxysporum f. sp. lycopersici isolates collected across Sinaloa: Bonny Best (susceptible to all races), UC-82-L (susceptible to races 2 and 3), F1 MH-1 (susceptible to race 3), and IR-3 (resistant to all races). A microconidial suspension was prepared for each isolate (1 × 106 CFU/ml) from cultures grown in potato dextrose broth with constant agitation (110 rpm) at 28°C for 7 days. Five 25-day-old seedlings (three fully expanded true leaves) from each differential cultivar were immersed in the appropriate microconidial suspension for 10 min, then individually transplanted into a pot containing 1 kg of sterilized commercial potting mix, and grown in a growth chamber at 25 to 28°C and 60 to 75% relative humidity for 5weeks with 14-h light/10-h darkness. Control plants (root dipped for 10 min in sterile water) were grown similarly and remained asymptomatic. Susceptible cv. Bonny Best showed typical symptoms of Fusarium wilt including epinasty, yellowing, defoliation, vascular necrosis, and wilt. None of these plants survived 25 days postinoculation for any of the isolates. All UC-82-L plants inoculated with each of the 26 isolates died before 35 days, indicating that none of the isolates was of race 1. F1 MH-1 plants only survived inoculation with 3 of the 26 isolates (11.5%), indicating that the 23 isolates that killed these plants (88.5% of the 26 isolates) were of race 3, and only 3 isolates were of race 2. All IR-3 plants inoculated with the 26 isolates survived. The isolates showed variation in response to the differential cultivar UC-82L in duration from inoculation to when the plants died (variation in isolate aggressiveness). The three F. oxysporum f. sp. lycopersici race 2 isolates were restricted to the Culiacan Valley, whereas the 23 F. oxysporum f. sp. lycopersici race 3 isolates were widely distributed across Sinaloa. Koch's postulates were confirmed by reisolating the fungus from the roots and stem base of each dead, inoculated plant (4). This study provides baseline data for future surveys to monitor changes in distribution of F. oxysporum f. sp. lycopersici races in Sinaloa, Mexico. References: (1) G. Cai et al. Phytopathology 93:1014, 2003. (2) P. Sánchez-Peña. Programa de Fomento y Apoyo a Proyectos de Investigación (PROFAPI), Universidad Autónoma de Sinaloa, México, 2007. (3) Secretaría de Agricultura, Ganadería, Desarrollo Rural, Pesca y Alimentación, Servicio de Información Agroalimentaria y Pesquera, México. www.siap.gob.mx , 2009. (4) B. A. Summerell et al. Plant Dis. 87:117, 2003.

Streptomyces Strains Induce Resistance to Fusarium oxysporum f. sp. lycopersici Race 3 in Tomato Through Different Molecular Mechanisms

“…Besides, new races of the mentioned pathogen (e.g., race 3) have emerged that can overcome host resistance (Reis et al, 2005). The symptoms of Fusarium wilt disease caused by race 3 are yellowing the lower leaves, vascular necrosis, epinasty, defoliation, plant stunting and ultimately plant death (Sanchez-Pena et al, 2010). Biological control of this pathogen has been the subject of many studies (Ben Abdallah et al, 2016).…”

Razas de Fusarium oxysporum f. sp. lycopersici en predios tomateros en San Luis Potosí

“…This study indicated the presence of only 2 and 3 races on the grounds discussed in San Luis Potosí. Ortega (2010) and Sánchez-Peña et al (2010) also reported the presence of races 2 and 3 of Fol in the state of Morelos and Sinaloa, respectively.…”

Molecular characterization and race identification of Fusarium oxysporum f. sp. lycopersici infecting tomato in India

“…For data analysis, the presence or absence of an allele at a particular locus was scored as 1 and 0, respectively, and the pairwise distance among the strains was calculated from the binary matrix using the Jaccard's coefficient. The resulting distance matrices were used to cluster the strains by the UPGMA (Unweighted Pair Group method using arithmetic means) method using NTSYSpc version 2.0 (Rohlf 1997).…”