Abstract:

Isolated microspore culture in cucumber was studied by using 10 different varieties of cucumber. Cotyledonary embryoids and plantlets were obtained from '7447' and 'Poinsett97' genotypes for the first time. The results showed that genotype and the developmental stage of microspore were the key factors in embryoid induction. The embryoid yield was different significantly among different genotypes. Embryoid yield per culture dish varied from 1.5～33.4. The late-uninucleate stage of microspore was found optimum for isolated microspore culture in cucumber. Cold-pretreatment (4 ℃) for 2～4 days also promoted embryoid induction, while the highest embryoid yield was obtained form microspore pre-treated at 4 ℃ for 2 days. The results also indicated that low concentration of exogenous hormones (0.5 mg·L^-1 2,4-D and 0.2 mg·L^-1 6-BA) were conductive to embryogenesis, whereas NLN and B₅ medium had no significant difference on embryoid induction. The regenerated plantlets were obtained only from cotyledonary embryoids and no plantlet was produced from the embryoids at other developmental stages.

Key words: cucumber, microspore culture, embryoid, plant regeneration