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Apomixis in flowering plants: an overview
1School of Biology, University of Newcastle upon Tyne, Newcastle upon Tyne NE1 7RU, UK. a.j.richards@ncl.ac.uk
Summary
Apomixis, or asexual reproduction via seeds, is common in perennial plants but often overlooked. This study explores its genetic basis and evolutionary advantages, particularly for agamospermy (seed-based apomixis).
Area of Science:
- Evolutionary Biology
- Plant Reproduction
- Genetics
Background:
- Apomixis, asexual reproduction through seeds, is prevalent in perennial plants (approx. 60% of British flora) but underrepresented in reproductive theory.
- While offering advantages like rapid colonization and longevity, apomixis often coexists with sexual reproduction, indicating underlying disadvantages.
Purpose of the Study:
- To investigate the genetic mechanisms and evolutionary implications of apomixis, with a focus on agamospermy (seed-based apomixis).
- To identify ideal genetic targets for manipulating agamospermy in plant breeding.
Main Methods:
- Analysis of genetic factors influencing apomixis and agamospermy.
- Examination of evolutionary pressures and genetic loads associated with apomixis.
- Identification of specific gene types and plant families suitable for genetic modification.
Main Results:
- Agamospermy, though uncommon, leverages seed attributes and favors the formation of co-adapted gene linkage groups.
- Agamospermy is typically associated with hybrids and exhibits heterosis, with potential endosperm genomic imbalance.
- While apomictic populations show variability, apomictic families are less diverse than sexual ones; sex may persist via pseudogamy or somatic recombination.
Conclusions:
- Fertile sexuals with a single, localized apomixis (A) gene, lacking genetic load and coexisting with sexuality, are prime candidates for genetic modification.
- Sporophytic apomixis in plants offers desirable traits for breeding, facilitating selection of both sexual and asexual offspring.