Plant & Animal Genomes XV Conference

January 13-17, 2007
Town & Country Convention Center
San Diego, CA

Reproductive Gene Candidates Linked With Apomixis

Joann A. Conner¹ , Heqiang Huo¹ , Yajuan Zeng¹ , Emidio Albertini² , Peggy Ozias-Akins¹

¹  Department of Horticulture, University of Georgia Tifton Campus, Tifton, GA 31793 USA

²  University of Perugia, Plant Biology and Agroenvironmental Biotechnology Dept., 06121 Perugia Italy

Apomixis, or asexual reproduction through seeds, is typified in Pennisetum squamulatum and relatives by premature termination of female meiosis and concurrent development of aposporous embryo sacs from somatic nucellar cells. The mature aposporous embryo sacs have four chromosomally unreduced nuclei and lack antipodal cells. The diploid egg evades fertilization and develops into an embryo through parthenogenesis. The central cell, however, requires fertilization in order to initiate the development of endosperm. We have genetically and cytogenetically characterized the region of the genome that is associated with apospory (the apospory-specific genomic region or ASGR). The ASGR is heterochromatic and physically large (>50 Mb) as defined by the nearest recombination break point; nevertheless, it contains transcribed genes, some of which play significant roles in reproduction in other species. One candidate gene of interest is ASGR-Baby Boom (BBM). Expression of the ASGR-linked gene has been observed in total inflorescence tissue from apomictic genotypes. The role of ASGR-BBM is being further explored by more detailed expression analysis and RNA silencing. Linkage of the ASGR with candidate genes from other species, e.g., APOSTART, also is being tested.