Detection and Monitoring of Greeneria uvicola and Colletotrichum acutatum Development on Grapevines by Real-Time PCR

Plant Disease (Impact Factor: 3.02). 03/2011; 95(3):298-303. DOI: 10.1094/PDIS-07-10-0537

ABSTRACT Bitter rot (Greeneria uvicola) and ripe rot (Colletotrichum acutatum, syn. C. simmondsii) occur frequently in subtropical grape-growing regions of Australia, where they cause yield loss and bitter taints in wine. To further advance the epidemiological studies of G. uvicola and C. acutatum and contribute toward their effective management and control, a rapid and reliable species-specific real-time polymerase chain reaction (PCR) method was developed based on the polymorphic portion of the internal transcribed spacer region of the two fungi. It was found that, within 6 to 8 h postinoculation, the assay could detect as little as 20 fg of genomic DNA and 10 conidia for both species. Artificially and naturally infected grape inflorescences and mature berries were analyzed by both conventional plating methods and real-time PCR. Fungal presence was demonstrated on all plant material but development was observed only on mature berries. The results demonstrate that the real-time PCR technique is a highly specific, rapid, and sensitive method that can be used to detect and study the dynamics of G. uvicola and C. acutatum during different stages of infection and on different grape tissues.

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    ABSTRACT: Species from different fungal genera have been indicated as responsible for the development of trunk diseases of grapevines. Greeneria uvicola is responsible for the bitter rot of Vitis vinifera grape bunches near harvest, and can also attack other Vitis species. In Uruguay, G. uvicola was isolated from dead arm-affected grapevines and as an endophyte from healthy canes. Cadophora luteo-olivacea is a phialophora-like ascomycete with a wide distribution that was isolated from asymptomatic wood tissues in Vitis and Petri disease-affected nursery plants in Uruguay. Pathogenicity of isolates of both species was evaluated on Vitis vinifera cv. Tannat and Cabernet Sauvignon, and rootstocks SO4 and 3309C. Specific primers were developed for the ITS rDNA region for both species. Number of plants showing discoloration, length of discoloration, number of re-isolations and amplifications confirmed the pathogenicity of G. uvicola isolates. Pathogenicity of the isolate of C. luteo-olivacea obtained from symptomatic tissues is discussed. Specific primers can be used to detect the presence of these fungi in asymptomatic tissues.
    Phytopathologia Mediterranea 01/2011; 50:S166. · 0.97 Impact Factor
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    ABSTRACT: Background and Aims: Ripe rot of grapes is widespread in subtropical vineyards of south-eastern Australia. We aimed to re-evaluate the causative agent(s), berry susceptibility, fungicide sensitivity and differences in histopathology. Methods and Results: Both Colletotrichum acutatum and C. gloeosporioides were shown to be responsible for ripe rot in three vineyards surveyed in the Hastings Valley, NSW in 2007 and 2009. Observation on detached berries of Vitis vinifera (cv. Cabernet Sauvignon and Chardonnay) revealed that C. acutatum had a faster infection rate than C. gloeosporioides. C. acutatum also formed appressoria and penetrated grape tissue faster than C. gloeosporioides, which produced longer hyphae on the berry surface before penetration. Both C. acutatum and C. gloeosporioides produced acervuli 48 h after inoculation. In contrast, spore germination rates and growth rates on potato dextrose agar were greater for C. gloeosporioides. The two species differed in their sensitivity to the fungicides benomyl, captan and triadimenol. C. acutatum was significantly more sensitive to captan and triadimenol, whereas C. gloeosporioides was more sensitive to benomyl. Conclusions: Both C. acutatum and C. gloeosporioides cause ripe rot of wine grapes in Australia. Subtle differences in the infection process may explain the relative prevalence of the two species. Significance of the Study: This study confirms the involvement of C. acutatum and C. gloeosporioides in ripe rot of grapes in Australia. Knowledge of growth characteristics and fungicide sensitivity of ripe rot pathogens should aid disease management strategies.
    Australian Journal of Grape and Wine Research 05/2011; 17(2):123 - 128. DOI:10.1111/j.1755-0238.2011.00143.x · 1.82 Impact Factor
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    Plant Pathology, 04/2012; , ISBN: 978-953-51-0489-6
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