Gametic embryogenesis through isolated microspore culture in mandarin (Citrus reticulata Blanco), Mandarino Tardivo Di Ciaculli: effect of meta-Topolin and temperature treatments
Giuseppe Cimò, Deborah Casamento, Daniela Torello Marinoni, Roberto Botta & Maria Antonietta Germanà
Haploid technology, allowing the single-step development of complete homozygous genotypes from heterozygous plants through gametic embryogenesis, has already an enormous impact on breeding programs of many important crops. Microspore embryogenesis can be carried out through in vitro culture of anther or isolated microspore. Experiments have been carried out via isolated microspore culture in Citrus reticulata (Blanco), Mandarino Tardivo di Ciaculli, investigating the influence of two culture media, of two plant growth regulator types and of two temperature treatments applied before the culture or just after the culture. After ten months of culture, for all the media tested, different structural features have been observed and registered: uninucleated, binucleated, multinucleated microspores, and, for the first time in mandarin isolated culture, calli and microspore-derived embryos. These results represent advancement in the knowledge of microspore embryogenesis in mandarin. Actually, this is the first time that embryo regeneration from isolated microspore cultures has been reported in mandarin, a genotype very recalcitrant to microspore embryogenesis.