Análise da expressão de genes do tipo MADS-Box em plantas de reprodução sexual e apomítica de Brachiaria brizantha

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Brachiaria genus has species containing sexual and apomictic plants. In apomictic reproduction, embryo sac differentiates from an unreduced cell and the embryo develops in absence of egg cell fertilization. MADS-Box genes are transcription factors that are involved in floral organ formation. The characterization of these homeotic genes in Brachiaria brizantha can contribute for the understanding of reproductive organs differentiation in apomicitc and sexual plants. The objective of the present work was to analyze the MADS-Box genes expression profile, aiming to correlate their activity with apomixis and sexuality. Two MADS-Box sequences, contigs 38 and 119, were identified in cDNA libraries of ovaries in megasporogenesis and megagametogenesis from sexual and apomictic Brachiaria brizantha. Phylogenetic analysis showed that the contig 38 deduced aminoacid sequence is close to AGL6 and contig 119 to SEPPALATA 2 (SEP2) from Arabidopsis thaliana. qRT-PCR and RT-PCR analysis indicated downregulation of the genes associated to both contigs in ovaries of apomictic B. brizantha during megasporogenesis. The transcripts of these genes were localized in ovaries, anthers and floral meristems of apomictic and sexual plants in different stages of development. Their expression was equivalent in apomictic and sexual plants, in case of BbrizAGL6. The data obtained at this work compared with results from other plants species reported at the literature suggest that the genes associated to contig 38 e 119 are involved with the identity of floral organs and the meristem of B. brizantha. It is suggested that these genes were named BbrizAGL e BbrizSEP, respectively.

ASSUNTO(S)

b-brizontha mads-box apomixia biologia molecular qrt-pcr

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