High-frequency somatic embryo production from unfertilized ovules of grapes

Somatic embryos were produced in large numbers from cultured, unfertilized ovules of Vitis vinifera, cultivars ‘Cabernet Sauvignon’ and ‘Grenache’, and of the hybrid grape ‘Gloryvine’ (V. vinifera × V. rupestris). Callus of nucellar origin was produced by culturing the ovule explants initially in Nitsch medium containing 5 μM 2,4-dichlorophenoxy acetic acid (2,4-D) or 5 μM β-naphthoxyacetic acid (NOA) plus 1 μM benzyladenine (BA), and then in a medium supplemented with NOA (10 μM) plus BA (1 μM). Embryos were produced when callus was transferred to basal medium containing no auxin or cytokinin. Secondary and tertiary embryos were formed by budding of primary somatic embryos. Prolonged culture of ovular callus in NOA (10 μM) plus BA (1 μM) gave rise to cell aggregates which developed into free-floating roots when transferred to basal medium.