Control of Flowering in the Grapevine (Vitis vinifera L.): Formation of Inflorescences in Vitro by Isolated Tendrils.

Tendrils produced from shoot tips of grapevine (Vitis vinifera L.) cultured in vitro on Nitsch's medium developed into inflorescences when 5 to 10 mum benzyladenine (BA) or 6-(benzylamino)-9-(2-tetrahydropyranyl)-9H-purine (PBA) were applied directly to the tendril tips. Inflorescences did not form on tendrils if the cytokinins were supplied in the agar. Tendrils cultured in agitated liquid medium containing BA, PBA, or zeatin riboside showed profuse branching and tendrils were transformed into inflorescences. Calyx and corolla (calyptra) stamens and pistils developed normally in the presence of both zeatin riboside and PBA, but micro- and macrosporogenesis were absent.Inflorescences were formed by tendrils from five cultivars (Muscat of Alexandria, Shiraz, Carbernet Sauvignon, Wortley Hall, and Sultana syn. Thomson Seedless) and also on tendrils from 12- to 15-week-old-seedlings.