MADS-box transcription factors show highly diverse regulatory functions in a wide variety of organisms. In this study, we characterized a MADS-box gene （BpMADS12） from the white birch （Betula platyphylla Suk）. Thi...MADS-box transcription factors show highly diverse regulatory functions in a wide variety of organisms. In this study, we characterized a MADS-box gene （BpMADS12） from the white birch （Betula platyphylla Suk）. This gene is a member of the suppressor of overexpression of CO 1/tomato MADS 3 class of MADS-box genes. We generated lines overexpressing BpMADS12 and found that these had higher levels of lignin compared to that observed in nontransgenic lines. Transcriptome anal- ysis revealed numerous changes in gene expression patterns. In total, 8794 differentially expressed genes were identified, including 5006 upregulated unigenes and 3788 downregulated unigenes in BpMADS-overexpression lines. Differentially expressed genes involved in the pathways for lignin and brassinosteroid biosynthesis were significantly enriched and may have contributed to phenotypic changes. The results from a quantitative RT-PCR analysis were consistent those obtained with the transcriptome analysis.Our transcriptome analysis, in combination with measure- ment of lignin level, indicated that BpMADS12 promotes lignin synthesis through regulation of key enzymes in response to brassinosteroid signaling. These results suggest that this MADS-box protein is crucial to all subsequent structural events and provide a good foundation for studies aiming to elucidate the developmental mechanisms underlying formation of wood.展开更多
Secondarily thickened cell walls of water-conducting vessels and tracheids and support-giving sclerenchyma cells contain lignin that makes the cell walls water impermeable and strong. To what extent laccases and perox...Secondarily thickened cell walls of water-conducting vessels and tracheids and support-giving sclerenchyma cells contain lignin that makes the cell walls water impermeable and strong. To what extent laccases and peroxidases contribute to lignin biosynthesis in muro is under active evaluation. We performed an in silico study of Norway spruce （Picea abies （L.） Karst.） laccases utilizing available genomic data. As many as 292 laccase encoding sequences （genes, gene fragments, and pseudogenes） were detected in the spruce genome. Out of the 112 genes annotated as laccases, 79 are expressed at some level. We isolated five fun-length laccase cDNAs from developing xylem and an extracellular lignin-forming cell culture of spruce. In addition, we purified and biochemically characterized one culture medium laccase from the lignin-forming cell culture. This laccase has an acidic pH optimum （pH 3.8-4.2） for coniferyl alcohol oxidation. It has a high affinity to coniferyl alcohol with an apparent Km value of 3.5μM; however, the laccase has a lower catalytic efficiency （Vmax/Km） for coniferyl alcohol oxidation compared with some purified culture medium peroxidases. The properties are discussed in the context of the information already known about laccases/coniferyl alcohol oxidases of coniferous plants.展开更多
基金financially supported by the National Science and Technology Program of China during the 12th Five-Year Plan Period(No.2013AA102704)the National Natural Science Foundation of China(NO:31200510)
文摘MADS-box transcription factors show highly diverse regulatory functions in a wide variety of organisms. In this study, we characterized a MADS-box gene （BpMADS12） from the white birch （Betula platyphylla Suk）. This gene is a member of the suppressor of overexpression of CO 1/tomato MADS 3 class of MADS-box genes. We generated lines overexpressing BpMADS12 and found that these had higher levels of lignin compared to that observed in nontransgenic lines. Transcriptome anal- ysis revealed numerous changes in gene expression patterns. In total, 8794 differentially expressed genes were identified, including 5006 upregulated unigenes and 3788 downregulated unigenes in BpMADS-overexpression lines. Differentially expressed genes involved in the pathways for lignin and brassinosteroid biosynthesis were significantly enriched and may have contributed to phenotypic changes. The results from a quantitative RT-PCR analysis were consistent those obtained with the transcriptome analysis.Our transcriptome analysis, in combination with measure- ment of lignin level, indicated that BpMADS12 promotes lignin synthesis through regulation of key enzymes in response to brassinosteroid signaling. These results suggest that this MADS-box protein is crucial to all subsequent structural events and provide a good foundation for studies aiming to elucidate the developmental mechanisms underlying formation of wood.
基金supported by University of Helsinki Research Funds (to A.K.)Academy of Finland (grant 251390 to A.K.)Societas pro Fauna et Flora Fennica (to H.A.M.)
文摘Secondarily thickened cell walls of water-conducting vessels and tracheids and support-giving sclerenchyma cells contain lignin that makes the cell walls water impermeable and strong. To what extent laccases and peroxidases contribute to lignin biosynthesis in muro is under active evaluation. We performed an in silico study of Norway spruce （Picea abies （L.） Karst.） laccases utilizing available genomic data. As many as 292 laccase encoding sequences （genes, gene fragments, and pseudogenes） were detected in the spruce genome. Out of the 112 genes annotated as laccases, 79 are expressed at some level. We isolated five fun-length laccase cDNAs from developing xylem and an extracellular lignin-forming cell culture of spruce. In addition, we purified and biochemically characterized one culture medium laccase from the lignin-forming cell culture. This laccase has an acidic pH optimum （pH 3.8-4.2） for coniferyl alcohol oxidation. It has a high affinity to coniferyl alcohol with an apparent Km value of 3.5μM; however, the laccase has a lower catalytic efficiency （Vmax/Km） for coniferyl alcohol oxidation compared with some purified culture medium peroxidases. The properties are discussed in the context of the information already known about laccases/coniferyl alcohol oxidases of coniferous plants.
