RESUMO

We investigated gene expression patterns that occur during taro corm development. Two-dimensional gel electrophoresis identified several different prevalent proteins that accumulate during corm development. Microsequencing studies indicated that some of these proteins are related to taste-modifying proteins, such as curculin and miraculin, and proteins found in other storage organs, such as sporamin and the Kunitz trypsin inhibitor. A curculin-encoding cDNA clone, designated as TC1, was identified that corresponds to a highly prevalent 1-kb corm mRNA. The TC1 mRNA accumulates during corm development, is more prevalent in corm apical than basal regions, and is either absent, or present at low concentrations, in other vegetative organs such as the leaf and root. In situ hybridization experiments showed that the TC1 mRNA is highly concentrated in corm storage parenchyma cells and is absent, or present in reduced concentrations, in other corm cells and tissues. Our results show that corm development is associated with the differentiation of specialized cells and tissues, and that these differentiation events are coupled with the temporal and spatial expression of corm-specific genes.

Assuntos

Expressão Gênica , Plantas Comestíveis/genética , Sequência de Aminoácidos , Diferenciação Celular , Biblioteca Gênica , Globulinas/genética , Globulinas/metabolismo , Dados de Sequência Molecular , Proteínas de Vegetais Comestíveis/genética , Proteínas de Vegetais Comestíveis/metabolismo , Plantas Comestíveis/citologia , Plantas Comestíveis/crescimento & desenvolvimento , RNA Mensageiro/genética , Homologia de Sequência , Homologia de Sequência de Aminoácidos

RESUMO

Two genes, BE2S1 and BE2S2, coding for methionine-rich albumins of Brazil nut (Bertholletia excelsa H.B.K.) have been cloned and their sequence determined. The genes are members of a multigene family and one of them, i.e. BE2S1, codes for one of the dominant 2S isoforms. Its expression is highly regulated during seed development and with respect to tissue specificity. Sequence analysis has shown that the genes contain one intron and that the promoter of BE2S1 shows a canonical TATA motif. The transcription initiation site is located 26 nucleotides downstream from the TATA box. Sequence comparison of the promoter regions of 2S genes from Brassica napus, Arabidopsis thaliana and B. excelsa revealed the presence of TGCA palindromic sequence that appear to be arranged in a 2S-specific manner.

Assuntos

Albuminas/genética , Alérgenos , Nozes/genética , Proteínas de Plantas/genética , Albuminas 2S de Plantas , Sequência de Aminoácidos , Antígenos de Plantas , Sequência de Bases , Northern Blotting , Southern Blotting , Clonagem Molecular , Regulação da Expressão Gênica/fisiologia , Íntrons/genética , Dados de Sequência Molecular , Família Multigênica/genética , Regiões Promotoras Genéticas/genética , Sequências Repetitivas de Ácido Nucleico/genética , Sementes/crescimento & desenvolvimento , Alinhamento de Sequência , TATA Box/genética