In vitro induction of haploid plants in unpollinated ovules, anther and microspore culture of Cucumis sativus

In order to increase the yield of haploid cucumber plants obtained from in vitro culture of unpollinated ovules, anther and microspore, we have studied several factors: the nature and concentration of plant growth regulators, the genotypes, the flower bud lengths, and the stages of microspore development. Among the different growth regulators tested, thidiazuron (TDZ) was the best for gynogenesis induction with an optimal concentration of 0.2 mg.L. Out of the ten evaluated genotypes, only cultivar ‘Gordion’ was able to develop the haploid plant through in vitro gynogenesis. Based on the histological studies we found that the best stages of the anther development for haploid induction are the late uninucleate microspore and the early bicellular pollen grains. Anther and microspore cultures differed in the embryogenic callus formation; callus was formed from anther somatic cells and from vegetative cells of pollen grain in anther and microspore cultures respectively. INTRODUCTION The androgenesis, gynogenesis and parthenogynesis are widely used for modern breeding programs of vegetables as a source of doubled haploid lines (DHLs). The partenogynesis is mostly used for cucumber DHLs production, while the application of androgenesis and gynogenesis to Cucumis sativus is still limited (Gemes-Juhasz et al. 2002; Ashok Kumar and Murthy 2004; Claveria et al. 2005; Song et al. 2007). Such factors as the plant genotype, growth conditions of the donor plants, the microspore developmental stage, pre-treatment of flower buds, the media and the culture conditions can influence androgenesis and gynogenesis (Bajaj 1990). The object of the present investigation was to determine the effect of different growth regulators, plant genotype, and stage of microspore development on induction of gynogenesis and androgenesis in cucumber. MATERIAL AND METHODS Plant material and surface sterilization of flower buds Ten cultivars of C. sativus, namely, ‘Hiziz’, ‘Gordion’, ‘Hana’, ‘Malen’, ‘Kadet’, ‘Asak’, ‘Reisa’, ‘Tristan’, ‘Tarantutka’, and ‘Rostovchanin’ were used in experiments with unpollinated ovules culture. Cultivars ‘Wodolei’ and ‘Rodnichok’ were used in experiments with anther and isolated microspores cultures. Buds and Cucurbitaceae 2008, Proceedings of the IX EUCARPIA meeting on genetics and breeding of Cucurbitaceae (Pitrat M, ed), INRA, Avignon (France), May 21-24th, 2008