NESPAL > Biotechnology and Plant Breeding > Research Projects > Apomixis Gene Discovery

Apomixis Gene Discovery: Ozias-Akins Biotechnology Lab
by Peggy Ozias

Agricultural production is dependent upon normal plant development, i.e. seed germination, vegetative growth, flowering, and fruit and seed development. Optimizing production efficiency requires detailed knowledge of a plant's life cycle and its interaction with biotic and abiotic factors. Our research has the long-term goal of enhancing crop production and one of these research directions is apomixis gene discovery.

Apomixis is a reproductive process resulting in the propagation of seed-derived progeny that are genetically identical to the seed-bearing parent. Genetic identity is preserved in this case because there is no meiotic reduction during female reproduction, although meiosis can occur normally in the male to produce viable, chromosomally-reduced pollen. We are attempting to clone genes responsible for the trait of apomixis from two naturally occurring apomicts in the grass family, Pennisetum squamulatum and Cenchrus ciliaris . P. squamulatum is related to the forage and grain crop, pearl millet. In fact, the two Pennisetum species can be crossed in order to recover apomictic interspecific hybrids. Molecular genetic studies have been conducted on these hybrids allowing us to conclude that apomixis is inherited as a dominant trait with Mendelian segregation, but since recombination in this region of the genome is repressed, multiple genes may be necessary to confer the trait. Currently we are studying the chromosomal location and gene content of this genomic region in two apomictic grasses.
Project abstracts and reports
http://cris.csrees.usda.gov
http://www.nsf.gov/awardsearch/showAward.do?AwardNumber=0115911
Selected Publications
Ozias-Akins, P., D. Roche, and W.W. Hanna. 1998. Tight clustering and hemizygosity of apomixis-linked molecular markers in Pennisetum squamulatum implies genetic control of apospory by a divergent locus which may have no allelic form in sexual genotypes. Proc. Natl. Acad. Sci. USA 95:5127-5132.

Roche, D., W.W. Hanna, and P. Ozias-Akins. 2001. Gametophytic apomixis, polyploidy, and supernumerary chromatin. Sex. Plant Reprod. 13:343-349.

Goel, S., Z. Chen, J.A. Conner, Y. Akiyama, W.W. Hanna, and P. Ozias-Akins. 2003. Physical evidence that a single hemizygous chromosomal region is sufficient to confer aposporous embryo sac formation in Pennisetum squamulatum and Cenchrus ciliaris. Genetics 163:1069-1082.

Ozias-Akins, P., Y. Akiyama, and W. W. Hanna. 2003. Molecular characterization of the genomic region linked with apomixis in Pennisetum/Cenchrus. Funct. Integr. Genomics 3:94-104.

Akiyama, Y., W.W. Hanna, P. Ozias-Akins. 2005. High-resolution mapping reveals that the apospory-specific genomic region (ASGR) in C. ciliaris is located on a heterochromatic and hemizygous region of a single chromosome. Theor. Appl. Genet. DOI 10.1007/s00122-005-0020-5.