Interaction between Esca-Associated Fungi, Grapevine Calli and Micropropagated Shoot Cultures of Grapevine

Abstract

Callus of the grapevine cv. Italia, micropropagated shoot cultures of the cv. Italia, Matilde and Sangiovese and callus of the tobacco cv. White Burley were cultivated on modified LS and MS-media. Phaeomoniella chlamydospora (Pch), Phaeoacremonium aleophilum (Pal) and Fomitiporia punctata (Fop) grew well in the presence of calli and vitroplants of all the grapevine cultivars which stimulated the growth of the fungi, but growth of the calli and vitroplants was reduced. All three fungi inhibited callus growth more strongly in grapevine than in tobacco. Fop had the greatest inhibitory effect on grapevine callus. Symptom severity also differed between cultivars. All three fungi invaded callus tissue after entirely overgrowing its surface. Hyphae were observed within the callus mass, where several cellular aggregates showed melanin-like deposits, particularly when invaded by Pal. On the foliar lamina of vitroplants symptoms were produced before and after the invasion of the plantlets by each fungus. Symptoms consisted in light green or chlorotic, rounded or irregular spots between the veins or along the leaf margin. The combination Pal vs. vitroplant gave the fastest host-pathogen response. The susceptibility or resistance of calli or vitroplants to escaassociated fungi could be a means to select grapevine for resistance to these fungi.