Characterization of Verticillium dahliae isolates from olive and susceptibility of local olive cultivars to Verticillium wilt in Istria, Croatia

Epidemics of Verticillium wilt in pepper fields of the central coast of California and isolates of Verticillium dahliae associated with these epidemics were characterized. The mean incidence of wilted plants per field ranged from 6.3 to 97.8% in fields with Anaheim, jalapeno, paprika, or bell peppers. In general, incidence of wilt in jalapeno and bell pepper crops was lower than in crops of other types of pepper. Inoculum density of V. dahliae in the surveyed pepper fields ranged from 2.7 to 66.6 microsclerotia g-1 dry soil, and the correlation between disease incidence and density of microsclerotia was high (r = 0.81, P < 0.01). Distribution of Verticillium wilt was aggregated in a majority of the pepper fields surveyed, but the degree of aggregation varied. Vegetative compatibility group (VCG) characterization of 67 isolates of V. dahliae indicated that 67% belonged to VCG 2, 22% to VCG 4, and 11% to a new group, designated VCG 6. The pathogenicity of isolates of V. dahliae from bell pepper and tomato plants was tested by inoculating 1-month-old bell pepper (cv. Cal Wonder) and tomato (cv. EP 7) seedlings and incubating the inoculated plants in the greenhouse. Seedlings of bell pepper were susceptible only to the isolates of V. dahliae from pepper, whereas seedlings of tomato were susceptible to both pepper and tomato isolates. Pepper isolates belonging to VCG 2, VCG 4, and VCG 6 were highly pathogenic to bell pepper and chili pepper. Temperatures between 15 and 25°C were optimal for mycelial growth of a majority of isolates of V. dahliae. Molecular characterization of pepper isolates of V. dahliae using a polymerase chain reaction (PCR)-based random amplified polymorphic DNA (RAPD) technique revealed minor variation among these isolates, but unique polymorphic banding patterns were observed for isolates belonging to VCG 6. Verticillium wilt of pepper is a major production constraint in the central coast of California. More aggressive isolates of V. dahliae may have been selected in this region as a result of intensive cropping practices.

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Phenotypic and Molecular Characterization of Verticillium dahliae, the Causal Agent of Verticillium Wilt of Olive in Tunisia

Journal of Applied Life Sciences International ◽

10.9734/jalsi/2016/23696 ◽

2016 ◽

Vol 4 (3) ◽

pp. 1-8

Author(s):

Yaakoub Gharbi ◽

Emna Bouazizi ◽

Mohamed Triki ◽

Radhouane Gdoura

Keyword(s):

Molecular Characterization ◽

Verticillium Wilt ◽

Verticillium Dahliae ◽

Causal Agent

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Resistance of Olive Cultivars to the Defoliating Pathotype of Verticillium dahliae

HortScience ◽

10.21273/hortsci.41.5.1313 ◽

2006 ◽

Vol 41 (5) ◽

pp. 1313-1316 ◽

Cited By ~ 29

Author(s):

Consuelo Martos-Moreno ◽

Francisco Javier López-Escudero ◽

Miguel Ángel Blanco-López

Keyword(s):

Verticillium Wilt ◽

Verticillium Dahliae ◽

Symptom Severity ◽

Rating Scale ◽

Breeding Programs ◽

Maximum Value ◽

Assessment Period ◽

Olive Cultivars ◽

Moderately Resistant ◽

Defoliating Pathotype

The resistance of 33 major olive cultivars to Verticillium dahliae was assessed in four experiments conducted under controlled conditions. Nine-month-old nursery olive plants were inoculated with a defoliating isolate (V117) of V. dahliae. Resistance was evaluated by assessing symptom severity using a 0–4 rating scale and estimating the area under disease progress curves with reference to the maximum value potentially reached over the assessment period (AUDPCP). The percentage of plants killed and that of plants that recovered from the disease were used as additional parameters for classifying the cultivars. Twenty-six of the 33 cultivars were found to be susceptible or extremely susceptible to the defoliating V. dahliae isolate. They exhibited values for AUDPCP higher than 45% with mortality higher than 37.5%. A second group of cultivars, which included `Cipresino', `Koroneiki', `Oblonga', and `Sevillenca', were classified as moderately resistant because they showed an important reduction of the final mean severity values and of values for AUDPCP that ranged from 23% to 42%. `Changlot Real', `Empeltre', and `Frantoio' were resistant to the defoliating isolate of V. dahliae. The resistance of `Empeltre' and `Frantoio', although previously reported, was consistently confirmed, because the two cultivars exhibited no dead plants and had very low values for AUDPCP and final disease. This is the first report of resistance of `Changlot Real' to Verticillium wilt based on ability of the plants to recover from infection and the absence of dead plants. These three cultivars will be useful for inclusion in Verticillium wilt-breeding programs.

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GhKWL1 Upregulates GhERF105 but Its Function Is Impaired by Binding with VdISC1, a Pathogenic Effector of Verticillium dahliae

International Journal of Molecular Sciences ◽

10.3390/ijms22147328 ◽

2021 ◽

Vol 22 (14) ◽

pp. 7328

Author(s):

Yang Chen ◽

Mi Zhang ◽

Lei Wang ◽

Xiaohan Yu ◽

Xianbi Li ◽

...

Keyword(s):

Gene Expression ◽

Transgenic Plants ◽

Gossypium Hirsutum ◽

Verticillium Wilt ◽

Verticillium Dahliae ◽

Defense Response ◽

Upland Cotton ◽

Effector Protein ◽

Positive Regulator ◽

Its Gene

Verticillium wilt, caused by Verticillium dahliae, is a devastating disease for many important crops, including cotton. Kiwellins (KWLs), a group of cysteine-rich proteins synthesized in many plants, have been shown to be involved in response to various phytopathogens. To evaluate genes for their function in resistance to Verticillium wilt, we investigated KWL homologs in cotton. Thirty-five KWL genes (GhKWLs) were identified from the genome of upland cotton (Gossypium hirsutum). Among them, GhKWL1 was shown to be localized in nucleus and cytosol, and its gene expression is induced by the infection of V. dahliae. We revealed that GhKWL1 was a positive regulator of GhERF105. Silencing of GhKWL1 resulted in a decrease, whereas overexpression led to an increase in resistance of transgenic plants to Verticillium wilt. Interestingly, through binding to GhKWL1, the pathogenic effector protein VdISC1 produced by V. dahliae could impair the defense response mediated by GhKWL1. Therefore, our study suggests there is a GhKWL1-mediated defense response in cotton, which can be hijacked by V. dahliae through the interaction of VdISC1 with GhKWL1.

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