Apomixis in Brachiaria decumbens stapf.: Gametophytic development and reproductive calendar

Brachiaria decumbens is a forage grass widely cultivated in tropical areas. This apomictic species reproduces mainly by facultative apospory. A compar ison of male and female gamete development between the diploid sexual ecoty pe and the tetraploid apomictic B. decumbens was made. Aspects of sporophyt ic and gametophytic development such as developmental stage, several morpho logical variations, and callose deposition during meiosis are compiled in a real-time reproductive calendar which can be used to select plants as well as reproductive stages. Based on this calendar, part of the differences ob served may be related to tetraploidy. Apomictic embryo sacs are formed earl ier than the sexual ones, and callose deposition during meiosis follows a d ifferent pattern in sexual and apomictic plants. Effects of apomixis are ex pressed during both male and female development.