RESUMO
Leaf shape elaboration and organ separation are critical for plant morphogenesis. We characterized the developmental roles of lobed leaflet1 by analyzing a recessive mutant in the model legume Medicago truncatula. An ortholog of Arabidopsis thaliana argonaute7 (AGO7), Mt-AGO7/lobed leaflet1, is required for the biogenesis of a trans-acting short interfering RNA (ta-siRNA) to negatively regulate the expression of auxin response factors in M. truncatula. Loss of function in AGO7 results in pleiotropic phenotypes in different organs. The prominent phenotype of the ago7 mutant is lobed leaf margins and more widely spaced lateral organs, suggesting that the trans-acting siRNA3 (TAS3) pathway negatively regulates the formation of boundaries and the separation of lateral organs in M. truncatula. Genetic interaction analysis with the smooth leaf margin1 (slm1) mutant revealed that leaf margin formation is cooperatively regulated by the auxin/SLM1 (ortholog of Arabidopsis PIN-formed1) module, which influences the initiation of leaf margin teeth, and the TAS3 ta-siRNA pathway, which determines the degree of margin indentation. Further investigations showed that the TAS3 ta-siRNA pathway and no apical meristem (ortholog of Arabidopsis cup-shaped cotyledon) antagonistically regulate both leaf margin development and lateral organ separation, and the regulation is partially dependent on the auxin/SLM1 module.
Assuntos
Medicago truncatula/crescimento & desenvolvimento , Proteínas de Plantas/fisiologia , RNA Interferente Pequeno/fisiologia , Sequência de Bases , Clonagem Molecular , Flores/citologia , Flores/genética , Flores/crescimento & desenvolvimento , Medicago truncatula/citologia , Medicago truncatula/genética , Dados de Sequência Molecular , Mutação , Folhas de Planta/citologia , Folhas de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , RNA Interferente Pequeno/química , Análise de Sequência de RNARESUMO
Basic helix-loop-helix (bHLH) genes are important regulators of development in plants. SbbHLH1, a Sorghum bicolor bHLH sequence, was isolated from a suppression subtractive hybridization library constructed using 13 independent brown midrib (bmr) mutants as the tester and wild-type sorghum as the driver. The gene was upregulated in at least five of the mutants at the five- to seven-leaf stage. Using a yeast expression system, the N-terminal portion of SbbHLH1 was shown to be required for proper transactivation. Its heterologous expression in Arabidopsis thaliana markedly reduced the plant's lignin content. It downregulated the lignin synthesis genes 4CL1, HCT, COMT, PAL1, and CCR1, and upregulated the transcription factors MYB83, MYB46, and MYB63. The hypothesis is proposed that SbbHLH1 has stronger effect on the regulation of lignin synthesis than the various MYB transcription factors, with a possible feedback mechanism acting on the MYB transcriptional regulators.
Assuntos
Arabidopsis/metabolismo , Lignina/biossíntese , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas/metabolismo , Sorghum/genética , Fatores de Transcrição/genética , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Regulação para Baixo , Expressão Gênica , Regulação da Expressão Gênica de Plantas , Sequências Hélice-Alça-Hélice , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/genética , Sorghum/química , Fatores de Transcrição/química , Fatores de Transcrição/metabolismoRESUMO
The bread wheat cultivar Shanrong No.3 (SR3) is a salinity tolerant derivative of an asymmetric somatic hybrid between cultivar Jinan 177 (JN177) and tall wheatgrass (Thinopyrum ponticum). To reveal some of the mechanisms underlying its elevated abiotic stress tolerance, both SR3 and JN177 were exposed to iso-osmotic NaCl and PEG stress, and the resulting gene expression was analysed using a customized microarray. Some genes associated with stress response proved to be more highly expressed in SR3 than in JN177 in non-stressed conditions. Its unsaturated fatty acid and flavonoid synthesis ability was also enhanced, and its pentose phosphate metabolism was more active than in JN177. These alterations in part accounted for the observed shift in the homeostasis related to reactive oxygen species (ROS). The specific down-regulation of certain ion transporters after a 0.5 h exposure to 340 mM NaCl demonstrated that Na(+) uptake occurred rapidly, so that the early phase of salinity stress imposes more than simply an osmotic stress. We discussed the possible effect of the introgression of new genetic materials in wheat genome on stress tolerance.
Assuntos
Tolerância ao Sal/genética , Plantas Tolerantes a Sal/genética , Transcriptoma , Triticum/genética , Adaptação Fisiológica/genética , Análise por Conglomerados , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Biblioteca Gênica , Vigor Híbrido/genética , Hibridização Genética , Análise de Sequência com Séries de Oligonucleotídeos , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Poaceae/efeitos dos fármacos , Poaceae/genética , Poaceae/metabolismo , Polietilenoglicóis/farmacologia , Proteoma/genética , Proteoma/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Salinidade , Cloreto de Sódio/farmacologia , Fatores de Tempo , Triticum/efeitos dos fármacos , Triticum/metabolismoRESUMO
Sorghum, a species able to produce a high yield of biomass and tolerate both drought and poor soil fertility, is considered to be a potential bioenergy crop candidate. The reduced lignin content characteristic of brown midrib (bmr) mutants improves the efficiency of bioethanol conversion from biomass. Suppression subtractive hybridization combined with cDNA microarray profiling was performed to characterize differential gene expression in a set of 13 bmr mutants, which accumulate significantly less lignin than the wild-type plant BTx623. Among the 153 differentially expressed genes identified, 43 were upregulated and 110 downregulated in the mutants. A semi-quantitative RT-PCR analysis applied to 12 of these genes largely validated the microarray analysis data. The transcript abundance of genes encoding l-phenylalanine ammonia lyase and cinnamyl alcohol dehydrogenase was less in the mutants than in the wild type, consistent with the expectation that both enzymes are associated with lignin synthesis. However, the gene responsible for the lignin synthesis enzyme cinnamic acid 4-hydroxylase was upregulated in the mutants, indicating that the production of monolignol from l-phenylalanine may involve more than one pathway. The identity of the differentially expressed genes could be useful for breeding sorghum with improved efficiency of bioethanol conversion from lignocellulosic biomass.
Assuntos
Regulação da Expressão Gênica de Plantas , Lignina/metabolismo , Folhas de Planta/metabolismo , Proteínas de Plantas/metabolismo , Sorghum/genética , Oxirredutases do Álcool/genética , Oxirredutases do Álcool/metabolismo , Genes de Plantas , Análise de Sequência com Séries de Oligonucleotídeos/métodos , Fenilalanina/metabolismo , Fenilalanina Amônia-Liase/genética , Fenilalanina Amônia-Liase/metabolismo , Folhas de Planta/genética , Proteínas de Plantas/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Sorghum/enzimologia , Transcinamato 4-Mono-Oxigenase/genética , Transcinamato 4-Mono-Oxigenase/metabolismoRESUMO
In order to investigate the amino acids (AAs) in plant cells, we explore an avenue for intracellular derivatization with FITC. In this method, FITC was used to mark AAs in living protoplasts derived from embryogenic calli of common wheat (Triticum aestivum L. c.v. Jinan 177) mediated by PEG. After FITC-derivatization, the AAs in the lysate were determined by CE. The result reveals that this PEG method can be used to transfer FITC into plant cells efficiently, which provides a good method for AA analysis in plant cells.