Different techniques for assessing the reproductive mode of weeping lovegrass plants, Eragrostis curvula (Schrad.) Nees

MEIER, MAURO; DIEGO ZAPPACOSTA; MARIA SARTOR; JUAN PABLO SELVA; SILVINA PESSINO; ECHENIQUE, V

Buenos Aires

Simposio; The 6th International Symposium on the Molecular Breeding of Forage and Turf; 2010

Weeping lovegrass is a forage grass cultivated in semiarid regions of the world that reproduces mainly by apomixis (diplospory), a process that involves the formation of asexual seeds avoiding the processes of meiosis and fertilization. The aim of this work was to evaluate different techniques (cytoembryology, callose deposition, flow cytometry and progeny test) to assess the reproductive mode of weeping lovegrass plants and to compare their effectiveness. Typical sexual and apomictic processes were clearly differentiated using cytoembryology and callose deposition was observed in sexual and apomictic genotypes. Previous studies in this and other diplosporous species indicated the presence of callose on the cell wall of the megaspore mother cell (MMC) in sexual but not in apomictic processes. Our results were not expected, since callose was found in apomictic genotypes, although the pattern in asexual megasporogenesis was clearly different from that observed in sexual processes, allowing us to use the test for discriminating between sexual and apomictic plants. Flow Cytometry Seed Screen (FCSS) was not useful to differentiate between sexual and apomictic plants using seed bulks because the embryo:endosperm DNA content ratio remains the same in sexual and apomictic plants. Progeny tests using RAPDs markers showed uniform patterns in offspring of apomictic plants and variable patterns in the offspring of sexual plants. The results of both cytological techniques and progeny test were similar and useful in order to assess the reproductive mode of this grass. The callose test turns out to be a useful tool for its rapidity compared to conventional cytoembryology and in addition to progeny tests with molecular markers.