Journal Article

Segregation for Sexual Seed Production in <i>Paspalum</i> as Directed by Male Gametes of Apomictic Triploid Plants

Eric J. Martínez, Carlos A. Acuña, Diego H. Hojsgaard, Mauricio A. Tcach and Camilo L. Quarin

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 100, issue 6, pages 1239-1247
Published in print November 2007 | ISSN: 0305-7364
Published online August 2007 | e-ISSN: 1095-8290 | DOI: http://dx.doi.org/10.1093/aob/mcm201
Segregation for Sexual Seed Production in Paspalum as Directed by Male Gametes of Apomictic Triploid Plants

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  • Ecology and Conservation
  • Evolutionary Biology
  • Plant Sciences and Forestry

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Background and Aims

Gametophytic apomixis is regularly associated with polyploidy. It has been hypothesized that apomixis is not present in diploid plants because of a pleiotropic lethal effect associated with monoploid gametes. Rare apomictic triploid plants for Paspalum notatum and P. simplex, which usually have sexual diploid and apomictic tetraploid races, were acquired. These triploids normally produce male gametes through meiosis with a range of chromosome numbers from monoploid (n = 10) to diploid (n = 20). The patterns of apomixis transmission in Paspalum were investigated in relation to the ploidy levels of gametes.

Methods

Intraspecific crosses were made between sexual diploid, triploid and tetraploid plants as female parents and apomictic triploid plants as male parents. Apomictic progeny were identified by using molecular markers completely linked to apomixis and the analysis of mature embryo sacs. The chromosome number of the male gamete was inferred from chromosome counts of each progeny.

Key Results

The chromosome numbers of the progeny indicated that the chromosome input of male gametes depended on the chromosome number of the female gamete. The apomictic trait was not transmitted through monoploid gametes, at least when the progeny was diploid. Diploid or near-diploid gametes transmitted apomixis at very low rates.

Conclusions

Since male monoploid gametes usually failed to form polyploid progenies, for example triploids after 4x × 3x crosses, it was not possible to determine whether apomixis could segregate in polyploid progenies by means of monoploid gametes.

Keywords: Apomixis; monoploid gametes; Paspalum notatum; Paspalum simplex; polyploidy; RAPD; SCAR; triploidy

Journal Article.  6780 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

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