Direct plant regeneration from leaf explants in cucumber (Cucumis sativus L.) is free of stable genetic variation

A new procedure is described for rapid and efficient plant regeneration from leaf explants of Cucumis sativus and C. anguria. The following factors were most important: young leaves, the NO₃: NH₄ ratio in the plant induction medium, small explants and the growth regulator combination. After about 4 weeks of culture under optimal growth conditions, the frequency of regeneration was 10–100% of explants. Six to 7 weeks were required to obtain well-rooted plants, which were mostly able to survive after transfer into soil. From a single young leaf of C. sativus cv. ‘Borszezagowski’, 135 plants could be regenerated. All plants transferred to a greenhouse were free of morphological or physiological abnormalities, flowered normally and bore fruits. The analysis of R₀ plants showed no genetic variation, whereas in the R₁ two new phenotypes, which were not transmittable to the R₂, were observed. This procedure is recommended for its production of homogeneous cucumber plants.