Oryzalin combined with adventitious regeneration for an efficient chromosome doubling of trihaploid kiwifruit.

Chromosome doubling of one parthenogenetic trihaploid from cultivar Hayward ofActinidia deliciosa was investigated. Two antimitotic agents, colchicine and oryzalin, appliedin vitro on shoots and leaves at different concentrations were compared with regard to their efficiency. Survival and regeneration rates were determined and ploidy level of regenerated plantlets was evaluated by flow cytometry. Differences were observed between the two antimitotic agents depending on whether shoots or leaves were treated. Hexaploid plantlets were obtained with highest efficiency by adventitious regeneration from leaves treated by oryzalin at 5 μM, constituting an original and promising result which was corroborated for another trihaploid clone. Dodecaploid plantlets were also induced but only from oryzalin treated leaves. On the other hand, colchicine applied to leaves was very phytotoxic. This study demonstrates that oryzalin combined with adventitious regeneration is particularly efficient to induce chromosome doubling of trihaploid kiwifruit.