ORIGINAL PAPER

Sexual Plant Reproduction

, Volume 10, Issue 5, pp 279-282

Dosage effects in the endosperm of diplosporous apomictic Tripsacum (Poaceae)

  • D. GrimanelliAffiliated withORSTOM, Institut Français de Recherche Scientifique pour le Développement en Coopération and CIMMYT, Centro Internacional de Mejoramiento de Maiz y Trigo, Apdo 6-641, Lisboa 27, Colonia Juarez, 06 600 Mexico DF, Mexico Fax +52-595-544 25; e-mail: dgrimanelli@cimmyt.mx
  • , Martha HernándezAffiliated withCIMMYT, Applied Biotechnology Center, Mexico City, Mexico
  • , Enrico PerottiAffiliated withCIMMYT, Applied Biotechnology Center, Mexico City, Mexico
  • , Yves SavidanAffiliated withORSTOM, Institut Français de Recherche Scientifique pour le Développement en Coopération and CIMMYT, Centro Internacional de Mejoramiento de Maiz y Trigo, Apdo 6-641, Lisboa 27, Colonia Juarez, 06 600 Mexico DF, Mexico Fax +52-595-544 25; e-mail: dgrimanelli@cimmyt.mx

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access

Abstract

 Imprinting in the endosperm of angiosperms, a phenomena by which expression of alleles differs depending on whether they originate from the male or female parent, has been shown to explain most failure of interploidy or interspecific crosses in plants. Because of imprinting, seeds develop normally only if a specific dosage is represented in the endosperm, with the relative contributions of genomes in the ratio of two maternal doses to one paternal dose (2m:1p). In Tripsacum, a wild relative of maize, all polyploids reproduce through the diplosporous type of apomixis. Diplospory results from meiotic failure in megasporocytes that develop into eight-nucleate unreduced female gametophytes. The male gametophytes remain unaffected. Flow cytometry was used to determine ploidy levels in the endosperm of both apomictic and sexual Tripsacum accessions. In both cases, fertilization appeared to involve only one sperm nucleus. Therefore, endosperm of apomictic Tripsacum develops normally even though the ratio of genomic contributions deviates from the normal 2m:1p ratio. Ratios of 2:1, 4:1, 4:2, 8:1 and 8:2 were observed, depending on both the ploidy level of the parents and the mode of reproduction. Thus, specific dosage effects are seemingly not required for endosperm development in Tripsacum. These findings suggest that evolution of diplosporous apomixis might have been restricted to species with few or no imprinting requirements, and the findings have strong implications regarding the transfer of apomixis to sexually reproducing crops.

Key words Apomixis Tripsacum Endosperm Imprinting Flow cytometry