Identification of Fusarium solani f. sp. cucurbitae Race 1 and Race 2 with PCR and Production of Disease-Free Pumpkin Seeds

Abstract

Fusarium solani f. sp. cucurbitae causes a fruit rot of cucurbits and is classified into two races that are actually distinct species: F. solani f. sp. cucurbitae race 1 (Fsc1) and race 2 (Fsc2). Because Fsc1 and Fsc2 are not easily distinguished morphologically, we developed a polymerase chain reaction (PCR) assay for rapid identification. Taxon-specific primers were designed from translation elongation factor 1-α sequences. Because clean seed is critical for disease control, we conducted experiments to determine if we could predict whether seed would be infected based on a visual rating of the fruit at harvest. In two trials in commercial pumpkin fields, eight fruit in each of four categories were selected: asymptomatic fruit, mildly infected fruit, severely infected fruit but without lesions extending into the seed cavity, and severely infected fruit with at least one lesion extending into the seed cavity. Isolates from both lesions and seed were identified as Fsc1 based on the PCR assay. No infected seed were recovered from fruit in which the surface was lesion-free or in which a lesion extended less than midway through the fruit flesh. Consequently, a rapid, visual inspection and exclusion of symptomatic fruit should be sufficient to obtain uninfected seed, even in infested fields.

Specific PCR Detection of Four Quarantine Fusarium Species in Korea

“…cucurbitae race 1 (S0687, S0688, and S0696) and race 2 (S0201, S0202, and S0203) isolates examined here formed two separate clades (99% BS), each along with reference strains, implying that the two races of F. solani f. sp. cucurbitae are phylogenetically distinct species (Mehl and Epstein, 2007). In addition, the other F. solani isolates (K40384, K41092, and K41093), whose forma speciales levels have not been identified, grouped within a different subclade, indicating that they are phylogenetically distinct from the F. solani f. sp.…”

“…These results support the classification of the two races of F. solani f. sp. cucurbitae as distinct species (Mehl and Epstein, 2007). PCR with the primer pair Tsolre1FM and Tredo1R amplified a 343-bp fragment from only the four F. redolens isolates that reside within a single phylogenetic clade (Fig.…”

“…cucurbitae races (Bogale et al, 2007;Mehl and Epstein, 2007), whereas no PCR primers have been developed for F. stilboides or F. semitectum var. majus.…”

“…This species can be divided into two different races (1 and 2): race 1 (telomorph: Nectria haematococca mating population I) causes crown, fruit, and root rot, whereas race 2 (telomorph: N. haematococca mating population V) affects only the fruit. Currently, the races are thought to be distinct species, as they are clearly different in terms of sexual mating behavior, other taxonomic characters, and DNA sequence homology (Mehl and Epstein, 2007). F. stilboides causes bark and fruit rot of citrus and coffee (Gerlach and Nirenberg, 1982), and is a member of the Lateritium clade of Fusarium; it is still difficult to distinguish it from some isolates of F. lateritium, which also belongs to the Lateritium clade (Geiser et al, 2005).…”

Morphology, Pathogenicity and Molecular Identification of Fusarium spp. Associated with Anise Seeds in Serbia

“…Fusarium species have already been recorded all over the world and are proved to be pathogens of many plants (Boughalleb et al, 2005;Mehl and Epstein, 2007). The virulence may be attributed either to a single gene or to a set of genes that confer a specific characteristic to the pathogen, such as production of host-specific toxins (Friesen et al, 2006;Van der Does and Rep, 2007).…”