RESUMO
Plant microspores can be reprogrammed from their normal pollen development to an embryogenic route in a process termed microspore embryogenesis or androgenesis. Stress treatment has a critical role in this process, inducing the dedifferentiation of microspores and conditioning the following androgenic response. In this study, we have used three barley doubled haploid lines with similar genetic background but different androgenic response. The Barley1 GeneChip was used for transcriptome comparison of these lines after mannitol stress treatment, allowing the identification of 213 differentially expressed genes. Most of these genes belong to the functional categories "cell rescue, defense, and virulence"; "metabolism"; "transcription"; and "transport". These genes were grouped into clusters according to their expression profiles among lines. A principal component analysis allowed us to associate specific gene expression clusters to phenotypic variables. Genes associated with the ability of microspores to divide and form embryos were mainly involved in changes in the structure and function of membranes, efficient use of available energy sources, and cell fate. Genes related to stress response, transcription and translation regulation, and degradation of pollen-specific proteins were associated with green plant production, while expression of genes related to plastid development was associated with albino plant regeneration.
Assuntos
Albinismo/genética , Desenvolvimento Embrionário/genética , Hordeum/anatomia & histologia , Hordeum/embriologia , Hordeum/genética , Pigmentação/genética , Pólen , Análise por Conglomerados , Perfilação da Expressão Gênica , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Hordeum/classificação , Dados de Sequência Molecular , Análise de Sequência com Séries de Oligonucleotídeos , Filogenia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Pólen/embriologia , Pólen/genética , Análise de Componente PrincipalRESUMO
Differential display was used to isolate cDNA clones showing differential expression in response to ABA, drought and cold in barley seedling shoots. One drought-regulated cDNA clone (DD12) was further analyzed and found to encode a branched-chain amino acid aminotransferase (HvBCAT-1). A genomic clone was isolated by probing the Morex BAC library with the cDNA clone DD12 and the structure of Hvbcat-1 was elucidated. The coding region is interrupted by six introns and contains a predicted mitochondrial transit peptide. Hvbcat1 was mapped to chromosome 4H. A comparison was made to rice and Arabidopsis genes to identify conserved structural patterns. Complementation of a yeast (Saccharomyces cerevisiae) double knockout strain revealed that HvBCAT-1 can function as the mitochondrial (catabolic) BCATs in vivo. Transcript levels of Hvbcat-1, increased in response to drought stress. As the first enzyme in the branched-chain amino acid (BCAA) catabolic pathway, HvBCAT-1 might have a role in the degradation of BCAA. Degradation of BCAA could serve as a detoxification mechanism that maintains the pool of free branched-chain amino acids at low and non toxic levels, under drought stress conditions.
Assuntos
Regulação da Expressão Gênica de Plantas , Hordeum/genética , Proteínas de Plantas/genética , Transaminases/genética , Água/metabolismo , Ácido Abscísico/farmacologia , Sequência de Aminoácidos , Aminoácidos de Cadeia Ramificada/metabolismo , Mapeamento Cromossômico , Cromossomos de Plantas , Clonagem Molecular , Sequência Conservada , Desidratação , Teste de Complementação Genética , Hordeum/enzimologia , Dados de Sequência Molecular , Reguladores de Crescimento de Plantas/farmacologia , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , RNA Mensageiro/metabolismo , Saccharomyces cerevisiae/genética , Alinhamento de Sequência , Análise de Sequência de Proteína , Transaminases/química , Transaminases/metabolismoRESUMO
Dehydrins (DHNs) compose a family of intrinsically unstructured proteins that have high water solubility and accumulate during late seed development, low temperature or water deficit conditions, and are thought to play a protective role in freezing and drought tolerance in plants. Twelve Dhn genes were previously described in the barley genome. Here, we report an additional member of this multigene family, Dhn13. The Dhn13 gene is located in chromosome 4 near marker MWG634 and encodes a 107-amino acid KS-type DHN. Semi-quantitative reverse transcriptase PCR data indicated that Dhn13 is constitutively expressed in seedling tissues and embryos of developing seeds. Microarray data were consistent with these results and showed a considerable increase of Dhn13 transcripts when plants were subjected to chilling and freezing temperatures. The highest transcript levels where observed in anthers. The presence of ABRE, MYC, DRE, and POLLEN1LELAT52 regulatory elements in the putative Dhn13 promoter region is in agreement with expression data.