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 - 5.46

CYTOMIXIS IN ALFALFA (MEDICAGO SATIVA L.)

A. MARIANI, M. BELLUCCI

Institute of Plant Genetics - Research Division of Perugia, CNR, via della Madonna Alta 130, 06128 Perugia, Italy

alfalfa, cytomixis, genetic control, pollen viability

Cytomixis has been defined as the migration of chromatin between adjacent cells through cytoplasmic connection channels. It occurs in a great number of plant species and has mainly been observed in pollen mother cells. In the present study we report the identification of a few cytomictic alfalfa plants, characterized by very little or no seed production. Cytomixis had never before been observed in alfalfa. Those alfalfa plants, the “mother plants”, were selfed and crossed with a normal control plant. Microsporogenesis analysis was performed on the mother plants, on the S1 and F1 plants and on the controls. The S1 and F1 plants, like the mother plants, were found to be cytomictic. Single or multiple chromatin bridges between two or more meiocytes were observed almost exclusively in prophase I. Some completely empty meiocytes were also observed. In addition to cytomixis, other meiotic abnormalities were found. Control plants showed an almost regular meiosis. The highest values of cytomixis were observed in the mother plants, and the lowest in their F1 progenies. Variability of cytomixis in the F1 plants is probably due to a heterozygotic condition of the parents for this trait. No significant correlation was found between cytomixis and pollen viability, even if the cytomictic plants showed low values of pollen viability. Our results indicate that in Medicago sativa cytomixis is very likely a natural phenomenon under direct genetic control, whose appearance does not seem to be determined by environmental factors. A possible association of cytomixis with the reproductive system, and the role of cytomixis in plant evolution are discussed.