Apomixis: Developmental Characteristics and Genetics

Asexual reproduction through seeds, or apomixis, is widespread in angiosperms, although does not happen frequently. It occurs in no major crop plant, but its deployment in major crops would afford advantages for breeding and maintenance of hybrid genotypes. Deployment is still a long-term goal, however, since the genetic mechanisms underlying apomixis in nature have not been determined nor has the isolation of apomictic mutants in sexual plants been achieved. Nevertheless, an increasing intensity of research toward these goals over the last decade has greatly expanded our knowledge of genome structure and gene expression in naturally occurring apomicts and female gametophyte development in sexual plants. A common working hypothesis is that apomixis is a “deregulation” of sexual processes and is increasingly supported by gene expression data. Nevertheless, the search for a unique trigger that initiates apomictic development still cannot be disqualified. Further characterization of female gametophyte-related genes and genomes of apomicts and model sexual plants will be fruitful for identifying overlaps in developmental networks.

Referees: Professor John G. Carman, Department of Plants, Soils and Biometeorology, Utah State University, Logan, UT 84322-4820

Keywords:

• adventitious embryony
• apospory
• asexual reproduction
• diplospory
• embryo sac
• female gametophyte

ACKNOWLEDGEMENTS

I thank Yajuan Zeng for original photographs of embryo sacs and Joann Conner for critical reading of the manuscript. USDA-NRI and NSF-PGRP have provided recent funding for apomixis research to P.O.-A.

Notes

Referees: Professor John G. Carman, Department of Plants, Soils and Biometeorology, Utah State University, Logan, UT 84322-4820

^a S—sexual, A—aposporous, D-diplosporous.

^b According to http://tolweb.org/tree?group=Angiosperms&contgroup=Spermatopsida.

^c According to RBG Kew C-value database (http://www.rbgkew.org.uk/cval/homepage.html)