1. Phaeomoniella chlamydospora on grapevine
(Vitis vinifera) with black-vascular symptoms in Chile
Gonzalo A. Díaz and Bernardo A. Latorre
Pontificia Universidad Católica de Chile, Facultad de Agronomía e Ingeniería Forestal,
Casilla , Santiago, Chile.
INTRODUCTION
Phaeomoniella chlamydospora is the most frequently pathogen associated to black-vascular streaking (BVS) of grapevine in Chile (2). The aim of this study was to determine the etiology of the BVS of grapevine and to characterize the isolates of Phaeomoniella associated with BVS.
‘Carmenere’
‘Cabernet Sauvignon’
Water
102
105
107
Trunk
Shoot
Fig. 4. Black vascular streaking of grapevine obtained in trunks (2 yr-old) and shoots (<1 yr-old), inoculated with P. chlamydospora after 15 and 2 mo., respectively. Means of 4 isolates.
METHODOLOGY
Isolates of Phaeomoniella (n=22) were identified morphologically and molecularly, using the ITS1-5.8S-ITS2 region of rDNA, and β-tubulin, using primers Bt2a and Bt2b (1, 3).
Pathogenicity was studied on: i) Axenic plantlets of grapevines. ii) Shoots of ‘Cabernet Sauvignon’. iii) Rooted grapevine ‘Carmenere’, and iv) Spurs of grapevines ‘Cabernet Sauvignon’. Inoculations were performed with mycelial plugs or conidial suspensions.
Fig. 3. In vitro plantlets inoculated with 2 µL of conidial suspension ( conidia/mL) of P. chlamydospora.
Fig. 5. Black vascular streaking obtained in ‘Cabernet Sauvignon’ grapevine spurs, inoculated with mycelia or conidia of P. chlamydospora after 7.5 months of incubation.
RESULTS
On PDA, yellow-olivaceous, very slow growing colonies and single cell conidia, ellipsoid, hyaline to slightly pigmented of 3.3x1.3 µm were obtained. Head of aggregated conidia were observed. Pycnidia were obtained on autoclaved grapevine chips (Fig. 1).
The ITS and β-tubulin analysis showing >98% identity with reference isolates (GenBank nos. AF and AF253968). These isolates were identified as P. chlamydospora (1).
Phaeomoniella isolates (95%) were obtained from BVS samples on PDA (Fig. 2).
Grapevine plantlets showed chlorosis, leaf reddish and stunted shoots (Fig. 3). BVS were obtained on plantlets, shoots, rooted grapevine and inoculated spurs (Fig. 4, 5). P. chlamydospora was reisolated in 99% of the inoculated tissues.
Fig. 2. P. chlamydospora. A. Colony on PDA. B. Conidiogenous cell and head of aggregated conidia (Bar=5 µm). C. Pycnidia on grapevine chips (Bar=100 µm). a b c
CONCLUSION
According to the results obtained the BVS of grapevine is caused by P. chlamydospora. BVS was associated to slight chlorosis and leaf reddish. These results showed that P. chlamydospora is the main pathogen associated with BVS of grapevines in Chile.
REFERENCES
1.Crous, P.W., and Gams, W Phytopathol. Mediterr. 39: 112.
2.Díaz, G.A., and Latorre, B.A Phytopathol. 101: S42.
3. White, T. J. et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, NY, 1990.
Fig. 1. Grapevine wood samples (no.) positive to P. chlamydospora. n=590.
Acknowledgments
This study was part of the thesis project of the first author who thanks Conicyt, Chile, for the scholarship to pursue his PhD studies and the financial support received through Conicyt project no