How to Avoid Sex: The Genetic Control of Gametophytic Apomixis

Grossniklaus, Ueli; Nogler, Gian A.; Dijk, Peter J. van

doi:10.2307/3871381

Cited by 43 publications

(60 citation statements)

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“…It is interesting to consider how this difference in mating system might arise. Sexual reproduction in an apomictic species can be constrained by three factors; a failure to initiate sexual development of embryos, an inability to produce viable reduced female gametes, and an inability successfully to fertilise these gametes (Asker, 1979;Grossniklaus et al, 2001).…”

Section: Discussionmentioning

confidence: 99%

Breeding systems and continuing evolution in the endemic Sorbus taxa on Arran

2004

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The Arran whitebeams Sorbus arranensis and S. pseudofennica are two endemic woody plant taxa that have evolved on Arran through hybridisation. S. arranensis is a triploid hybrid between the widespread diploid S. aucuparia and the rare tetraploid S. rupicola. S. pseudofennica is a tetraploid formed by crossing between S. arranensis and S. aucuparia. In order to determine the mating systems of the two endemic species six maternal trees of each taxon together with 10-12 of their seed offspring were scored for their phenotype at three microsatellite loci and one nuclear intron locus. All seeds of S. arranensis were identical in phenotype to their maternal parents. In S. pseudofennica, 17.5% of all seeds differed in marker phenotype from their maternal parent. The proportion of seed with nonmaternal phenotypes varied significantly among maternal trees of S. pseudofennica. The results suggest that the triploid S. arranensis is an obligate apomict, whereas the tetraploid S. pseudofennica is a facultative apomict. Molecular marker analysis of three trees from Arran with an unusual leaf morphology indicates that they are the product of sexual reproduction by S. pseudofennica, and may originate from hybridisation with S. aucuparia. This research demonstrates that the Sorbus taxa on Arran are participants in an active evolutionary process generating novel biodiversity. Conservation programmes for these taxa should aim to preserve this evolutionary process rather than the individual taxonomic entities that it produces.

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Section: Discussionmentioning

confidence: 99%

Breeding systems and continuing evolution in the endemic Sorbus taxa on Arran

2004

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“…By contrast, plant scientists consider that a positive and inheritable genetic programme controls apomixis and have relied on classical breeding experiments to transfer apomixis genes to sexual crop plants [14]. Such an approach would greatly simplify breeding schemes and enable the fixation of any genotype including those of the F 1 hybrids.…”

Section: Elucidating the Genetic Basis Of Apomixismentioning

confidence: 99%

Harnessing the developmental potential of nucellar cells: barriers and opportunities

Ranganath

2004

Trends in Biotechnology

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“…However, in Taraxacum officinale, Poa pratensis and Erigeron annuus, apomeiosis does not always cosegregate with other features of apomixis. In all species tested there is strong suppression of recombination around the apomeiosis locus, suggesting that apomixis may be controlled by many genes that are inseparably linked in one or two coadapted complexes (Grimanelli et al 2001;Grossniklaus et al 2001).…”

Section: (B) Endosperm Development In Apomictsmentioning

confidence: 99%

“…Although apomixis loci have been mapped in several species (Grimanelli et al 2001;Grossniklaus et al 2001), none has yet been sequenced. Genes involved in apomixis are also being pursued by other techniques, such as differential display to isolate mRNAs expressed in apomictic rather than sexual flowers (Pessino et al 2001).…”

Section: Engineering Apomixismentioning

confidence: 99%

Genetic mechanisms of apomixis

Spielman

Vinkenoog

Scott

2003

Phil. Trans. R. Soc. Lond. B

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The introduction of apomixis to crops would allow desirable genotypes to be propagated while preventing undesirable gene flow, but so far there has been little success in transferring this trait from a natural apomict to another species. One explanation is the sensitivity of endosperm to changes in relative maternal and paternal contribution owing to parental imprinting, an epigenetic system of transcriptional regulation by which some genes are expressed from only the maternally or paternally contributed allele. In sexual species, endosperm typically requires a ratio of two maternal genomes to one paternal genome for normal development, but this ratio is often altered in apomicts, suggesting that the imprinting system is altered as well. We present evidence that modification of DNA methylation is one mechanism by which the imprinting system could be altered to allow endosperm development in apomicts. Another feature of natural apomixis is the modification of the normal fertilization programme. Sexual reproduction uses both sperm from each pollen grain, but pseudogamous apomicts, which require a sexual endosperm to support the asexual embryo, often use just one. We present evidence that multiple fertilization of the central cell is possible in Arabidopsis thaliana , suggesting that pseudogamous apomicts may also need to acquire a mechanism for preventing more than one sperm from contributing to the endosperm. We conclude that strategies to transfer apomixis to crop species should take account of endosperm development and particularly its sensitivity to parental imprinting, as well as the mechanism of fertilization.

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How to Avoid Sex: The Genetic Control of Gametophytic Apomixis

Abstract: Patterns of gene action in plant development revealed by enhancer trap and gene trap transposable elements. Genes Dev. 9,

Cited by 43 publications

References 0 publications

Breeding systems and continuing evolution in the endemic Sorbus taxa on Arran

Breeding systems and continuing evolution in the endemic Sorbus taxa on Arran

Harnessing the developmental potential of nucellar cells: barriers and opportunities

Genetic mechanisms of apomixis

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