First report of Verticillium dahliae causing verticillium wilt of Solanum aethiopicum in Italy

I. Camele¹*, C. Marcone¹, A. Caponero², A. Ambrico², C. Nigro³ and G.L. Rana¹

¹ Università degli Studi della Basilicata, Dipartimento di Biologia, Difesa e Biotecnologie Agro-Forestali, Viale Ateneo Lucano, 10 – 85100 Potenza, Italy
² Agenzia Lucana per lo Sviluppo e l’Innovazione in Agricoltura (A.L.S.I.A.), Azienda Agricola Sperimentale Dimostrativa “Pantanello”, S.S. Jonica 106, - 75010 Metaponto, Italy
³ Agenzia Lucana per lo Sviluppo e l’Innovazione in Agricoltura (A.L.S.I.A.), Azienda Agricola Sperimentale Dimostrativa “Bosco Galdo”, Via Grumentina, 119, - 85050 Villa d’Agri (PZ), Italy

*camele@unibas.it

Accepted for publication 19/09/05

Solanum aethiopicum (African eggplant) is a very important vegetable throughout tropical Africa, especially in the less humid regions. It is also cultivated in some areas of southern Italy. In the last summer, a wilt disease of African eggplant was observed at one location in the Basilicata region (southern Italy). The most characteristic symptoms included yellowing, stunting, gradual wilting and brownish discoloration of vascular tissues. To elucidate the etiology of the disease, detection and identification of the causal agent(s) using both traditional and polymerase chain reaction (PCR)-based methods were attempted. Verticillium dahliae was consistently identified on the basis of its morphological features according to the description of Smith (1965), when cultured on potato dextrose agar (PDA) from small pieces of petiole and stem tissues taken from diseased plants. With PCR assays, using the primer pair ITS5/ITS4 (White et al., 1990), which are directed to fungal nuclear ribosomal DNA (rDNA) repeat sequences, an amplification product of approximately 560 bp was obtained using total DNA extracted from wilt affected-African eggplant tissues, as well as from fresh mycelium of the corresponding pure culture-maintained isolate. No PCR products were obtained with total DNA from asymptomatic African eggplants. Sequence analysis of the ITS5/ITS4 amplicons revealed that V. dahliae-infected African eggplant isolate (GenBank accession no. AJ970308) is identical to a Greek strain of V. dahliae (GenBank accession no. AF104926).

Figure 1: Yellowing and wilting on a leaf of Solanum aethiopicum infected by Verticillium dahliae

To fulfil Koch’s postulates, ten healthy African eggplant seedlings were experimentally inoculated by dipping their trimmed roots in a single-conidial suspension containing 1.5 x 10⁶ CFU per ml and obtained from 10-day-old colonies of the V. dahliae-infected African eggplant pure culture-maintained isolate. All inoculated plants showed symptoms identical to those of naturally infected plants. V. dahliae was consistently reisolated from inoculated plants. This appears to be the first report of African eggplant infection by V. dahliae.

The work was partially supported by funds from A.L.S.I.A..

Smith HC, 1965. The morphology of Verticillium albo-atrum, V. dahliae, and V. tricopus. New Zealand Journal of Agricultural Research 8, 450-478.

White TJ, Bruns T, Lee S, Taylor J, 1990. Amplification and direct sequencing of fungal ribosomal RNA genes for phylogenetics. In: Innis MA, Gelfand DH, Sninsky JJ, White TJ, eds. PCR Protocols. San Diego, California: Academic Press, 315-322.

The British Society for Plant Pathology