RESUMO
The Arabidopsis FLC gene encodes a MADS domain protein that acts as a repressor of flowering. Late-flowering vernalization-responsive ecotypes and mutants have high steady-state levels of FLC transcript, which decrease during the promotion of flowering by vernalization. Therefore, FLC has a central role in regulating the response to vernalization. We have isolated an Arabidopsis gene, MAF1, which encodes a protein that is closely related to FLC. Overexpression studies demonstrate that MAF1 produces comparable effects to FLC, and likely has a similar function in the regulation of flowering. In contrast to FLC, however, MAF1 expression shows a less clear correlation with the vernalization response. In addition, MAF1 overexpression does not influence FLC transcript levels. Thus, MAF1 likely acts downstream or independently of FLC transcription. We further report identification of a cluster of four additional FLC-like genes in the Arabidopsis genome.
Assuntos
Arabidopsis/fisiologia , Proteínas de Ligação a DNA/fisiologia , Fatores de Transcrição/fisiologia , Sequência de Aminoácidos , Arabidopsis/genética , Sequência de Bases , Primers do DNA , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/genética , Proteínas de Domínio MADS , Dados de Sequência Molecular , Filogenia , Proteínas de Plantas , Homologia de Sequência de Aminoácidos , Fatores de Transcrição/química , Fatores de Transcrição/genéticaRESUMO
In planta Agrobacterium-mediated transformation combined with a soil-based herbicide selection for transgenic plants was used to recover large numbers of transgenic Arabidopsis plants for functional genomic studies. A tissue-culture-free system for generating transgenic plants was achieved by infiltrating Arabidopsis plants with Agrobacterium tumefaciens harboring a binary T-DNA vector containing the phosphinothricin acetyltransferase gene from Streptomyces hygroscopicus, and by selecting transgenic Arabidopsis growing in soil by foliar application of the herbicide Finale (phosphinothricin). Analysis of herbicide-resistant plants indicated that all were transgenic and that the T-DNA transformation process occurred late during flower development, resulting in a preponderance of independently derived T-DNA insertions. T-DNA insertions were usually integrated in a concatenated, rearranged form, and using linkage analysis, we estimated that T1 plants carried between one and five T-DNA loci. Using pooling strategies, both DNA and seed pools were generated from about 38,000 Arabidopsis plants representing over 115,000 independent T-DNA insertions. We show the utility of these transgenic lines for identifying insertion mutations using gene sequence and PCR-based screening.
