Identification of differentially expressed cDNA sequences in ovaries of sexual and apomictic plants of Brachiaria brizantha

Abstract

The isolation of genes associated with apomixis would improve understanding of the molecular mechanism of this mode of reproduction in plants as well as open the possibility of transfer of apomixis to sexual plants, enabling cloning of crops through seeds. Brachiaria brizantha is a highly apomictic grass species with 274 tetraploid apomicts accessions and only one diploid sexual. In this study we have compared gene expression in ovaries at megasporogenesis and megagametogenesis of sexual and apomictic accessions of B. brizantha by differential display (DD-PCR), with 60 primer combinations. Specificity of 65 cloned fragments, checked by reverse northern blot analysis, showed that 11 clones were differentially expressed, 6 in apomictic ovaries, 2 in sexual and 3 in apomictic and sexual, but at different stages. Of the 6 sequences isolated that were preferentially expressed in the apomictic accession: one sequence was from ovaries at megasporogenesis stage; three were from megagametogenesis stage; two were from both stages. Of the two sequences isolated from the sexual accessions, one showed expression in ovaries at megagametogenesis, while the other sequence was shown to be specific to both stages. Three sequences were from megasporogenesis stage in apomicts but were also detected at megagametogenesis in sexual plants. Sequence analysis showed that 5 of the 11 clones had no apparent homologues in the protein database. Some of the clones identified as apomictic-specific shared homology with known genes enabling their functional annotation. The relationships of these functions to the generation of the apomictic trait are discussed.

Variabilidade genética de caracteres forrageiros em Paspalum

“…Este fato aumenta os riscos de perda de genótipos por fatores abióticos e bióticos (Adamowski et al, 2005). Porém, a utilização de hibridizações, quando um dos genitores apresenta reprodução sexuada, pode gerar variabilidade e possibilitar a seleção de progênies elite, com fixação imediata dos caracteres de interesse em razão da apomixia (Rodrigues et al, 2003;Acuña et al, 2009).…”

A Conserved Apomixis-Specific Polymorphism Is Correlated with Exclusive Exonuclease Expression in Premeiotic Ovules of Apomictic Boechera Species

“…Several candidate apomixis genes have been found by comparing sexual and apomictic flower transcriptomes in different plant species (Vielle-Calzada et al, 1996;Chen et al, 1999;Pessino et al, 2001;Rodrigues et al, 2003;Albertini et al, 2004). Here, we describe the APOLLO gene (for apomixis-linked locus), which shows differential expression between apomictic and sexual premeiotic ovules with regard to a specific group of alleles that share several apomixisspecific polymorphisms.…”

SERK and APOSTART. Candidate Genes for Apomixis in Poa pratensis

“…(Leblanc et al, 1997;Dusi, 2001;Rodrigues et al, 2003), Pennisetum sp. (Vielle-Calzada et al, 1996;Jessup et al, 2003), Paspalum sp.…”