RESUMEN
Secondary wall thickening in the sclerenchyma cells is strictly controlled by a complex network of transcription factors in vascular plants. However, little is known about the epigenetic mechanism regulating secondary wall biosynthesis. In this study, we identified that ARABIDOPSIS HOMOLOG of TRITHORAX1 (ATX1), a H3K4-histone methyltransferase, mediates the regulation of fiber cell wall development in inflorescence stems of Arabidopsis thaliana. Genome-wide analysis revealed that the up-regulation of genes involved in secondary wall formation during stem development is largely coordinated by increasing level of H3K4 tri-methylation. Among all histone methyltransferases for H3K4me3 in Arabidopsis, ATX1 is markedly increased during the inflorescence stem development and loss-of-function mutant atx1 was impaired in secondary wall thickening in interfascicular fibers. Genetic analysis showed that ATX1 positively regulates secondary wall deposition through activating the expression of secondary wall NAC master switch genes, SECONDARY WALL-ASSOCIATED NAC DOMAIN PROTEIN1 (SND1) and NAC SECONDARY WALL THICKENING PROMOTING FACTOR1 (NST1). We further identified that ATX1 directly binds the loci of SND1 and NST1, and activates their expression by increasing H3K4me3 levels at these loci. Taken together, our results reveal that ATX1 plays a key role in the regulation of secondary wall biosynthesis in interfascicular fibers during inflorescence stem development of Arabidopsis.
Asunto(s)
Proteínas de Arabidopsis/fisiología , Arabidopsis/metabolismo , Pared Celular/metabolismo , Regulación de la Expresión Génica de las Plantas/fisiología , Código de Histonas , N-Metiltransferasa de Histona-Lisina/fisiología , Histonas/genética , Inflorescencia/metabolismo , Proteínas de Plantas/genética , Tallos de la Planta/metabolismo , Factores de Transcripción/fisiología , Transcriptoma , Proteínas de Arabidopsis/biosíntesis , Proteínas de Arabidopsis/genética , Inmunoprecipitación de Cromatina , Regulación de la Expresión Génica de las Plantas/genética , Ontología de Genes , Genes de Plantas , Histonas/metabolismo , Lignina/metabolismo , Proteínas de Plantas/metabolismo , Tallos de la Planta/ultraestructura , ARN de Planta/biosíntesis , ARN de Planta/genética , Factores de Transcripción/biosíntesis , Factores de Transcripción/genética , Xilanos/metabolismoRESUMEN
Biomass fast pyrolysis is one of the most promising technologies for biomass utilization. In order to increase its economic potential, pyrolysis gas is usually recycled to serve as carrier gas. In this study, biomass fast pyrolysis was carried out in a fluidized bed reactor using various main pyrolysis gas components, namely N(2), CO(2), CO, CH(4) and H(2), as carrier gases. The atmosphere effects on product yields and oil fraction compositions were investigated. Results show that CO atmosphere gave the lowest liquid yield (49.6%) compared to highest 58.7% obtained with CH(4). CO and H(2) atmospheres converted more oxygen into CO(2) and H(2)O, respectively. GC/MS analysis of the liquid products shows that CO and CO(2) atmospheres produced less methoxy-containing compounds and more monofunctional phenols. The higher heating value of the obtained bio-oil under N(2) atmosphere is only 17.8 MJ/kg, while that under CO and H(2) atmospheres increased to 23.7 and 24.4 MJ/kg, respectively.
Asunto(s)
Biocombustibles , Biotecnología/métodos , Calor , Lignina/química , Componentes Aéreos de las Plantas/química , Zea mays , Dióxido de Carbono/química , Monóxido de Carbono/química , China , Hidrógeno/química , Metano/química , Nitrógeno/químicaRESUMEN
Square-planar polypyridine platinum(II) complexes have been introduced into a silica/polymer matrix by covalent ligand modification. The photophysical properties of the supported matrices are well retained as their model complexes, and the quantum yields for singlet oxygen ((1)O(2)) generation are comparable with that of TPP (tetraphenylporphyrin) under similar conditions. A preliminary application in photosensitized oxidation indicates the silica/polymer-supported matrices are promising, which can be reused without loss of reactivity by a simple filtration. Moreover, the polymer-supported matrix exhibits excellent compatibility in various solvents.