Proceedings of the XLVII Italian Society of Agricultural Genetics - SIGA Annual Congress

Verona, Italy - 24/27 September, 2003

ISBN 88-900622-4-X

Poster Abstract - 2.20

GENETIC ANALYSIS OF CITRUS RETICULATA BLANCO REGENERANTS OBTAINED FROM IN VITRO ANTHER CULTURE

B. Chiancone*, M. A. Germaná*, O. Olivares**, L. Navarro**

*) Dipartimento di Colture Arboree, Facoltá di Agraria, Universitá degli Studi di Palermo, Viale delle Scienze 11, 90128 Palermo, Italia

**) Departamento de Protección Vegetal y Biotecnología, Instituto Valenciano de Investigaciones Agrarias, Apartado Oficial 46113, Moncada, Valencia 46113

mandarins, anther culture, embryogenesis, molecular markers

Mandarins (Citrus reticulata Blanco) and their hybrids are one of the most popular Citrus species worldwide. They are grown in more than 80 countries, representing the 20% of the world Citrus production.

The Mandarino Tardivo di Ciaculli (MTC) and the mandarin Avana are the most important mandarin cultivars in Italy; MTC was selected as a mutation of the Common Mandarin and it is widely cultivated because of its delay in the ripening. In fact the fruits can be collected from the first days of February until middle of April, and although the fruit size is pretty small and with seeds, the flesh quality is really good. Thus, availability of a MTC cultivar with no seeds would have a big impact on the Italian citrus industry.

Since citrus conventional breeding faces different problems related to particular biology of these species, biotechnology appears as an alternative to improve them.

Anther culture is considered a routinely method to obtain haploids. Microspores under some culture conditions may change their gametic pathway that would lead to pollen formation, to develop embryoids or embryogenic callus via androgenesis. Haploid plants may have many applications for citrus breeding: easier mutations detection; double-haploids formation by diploidization of their chromosomes, allowing recovery in just one generation of homozygous plants, what is very difficult in tree plants. Moreover haploid lines can be used for genetic trasformation and as parents in protoplast fusion with diploid plants in order to obtain triploids, which are particularly important since they are seedless.

Actually by anther culture it is possible to recover diploid embryoids too. They can originate from the microspores and then duplicate their chromosomal number, so they are homozygous, or they may come from the somatic tissue of the anther, so they are heterozygous as the mother plant. Those somatic calli and plants have high value in citrus breeding, since they can be used for protoplast fusion, genetic trasformation or in vitro germplasm storage.

This research reports the molecular characterization of several embryoids and plants obtained from anther culture of MTC. The regenerants have been analysed with a flow cytometer to establish their ploidy level, and characterized by microsatellites, in order to determine if they are doubled-haploid or heterozygous somatic plants and to determine possible gametoclonal or somaclonal variation.