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- Fugelstad, Johanna, et al.
(författare)
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Identification of the cellulose synthase genes from the Oomycete Saprolegnia monoica and effect of cellulose synthesis inhibitors on gene expression and enzyme activity
- 2009
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Ingår i: Fungal Genetics and Biology. - : Elsevier BV. - 1087-1845 .- 1096-0937. ; 46:10, s. 759-767
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Tidskriftsartikel (refereegranskat)abstract
- Cellulose biosynthesis is a vital but yet poorly understood biochemical process in Oomycetes. Here, we report the identification and characterization of the cellulose synthase genes (CesA) from Saprolegnia monoica. Southern blot experiments revealed the occurrence of three CesA homologues in this species and phylogenetic analyses confirmed that Oomycete CesAs form a clade of their own. All gene products contained the D,D,D,QXXRW signature of most processive glycosyltransferases, including cellulose synthases. However, their N-terminal ends exhibited Oomycete-specific domains, i.e. Pleckstrin Homology domains, or conserved domains of an unknown function together with additional putative transmembrane domains. Mycelial growth was inhibited in the presence of the cellulose biosynthesis inhibitors 2,6-dichlorobenzonitrile or Congo Red. This inhibition was accompanied by a higher expression of all CesA genes in the mycelium and increased in vitro glucan synthase activities. Altogether, our data strongly suggest a direct involvement of the identified CesA genes in cellulose biosynthesis.
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| 2. |
- Guerriero, Gea, et al.
(författare)
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The RY/Sph element mediates transcriptional repression of maturation genes from late maturation to early seedling growth
- 2009
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 184:3, s. 552-565
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Tidskriftsartikel (refereegranskat)abstract
- P>In orthodox seeds, the transcriptional activator ABI3 regulates two major stages in embryo maturation: a mid-maturation (MAT) stage leading to accumulation of storage compounds, and a late maturation (LEA) stage leading to quiescence and desiccation tolerance. Our aim was to elucidate mechanisms for transcriptional shutdown of MAT genes during late maturation, to better understand phase transition between MAT and LEA stages. Using transgenic and transient approaches in Nicotiana, we examined activities of two ABI3-dependent reporter genes driven by multimeric RY and abscisic acid response elements (ABREs) from a Brassica napus napin gene, termed RY and ABRE, where the RY reporter requires ABI3 DNA binding. Expression of RY peaks during mid-maturation and drops during late maturation, mimicking the MAT gene program, and in Arabidopsis thaliana RY elements are over-represented in MAT, but not in LEA, genes. The ABI3 transactivation of RY is inhibited by staurosporine, by a PP2C phosphatase, and by a repressor of maturation genes, VAL1/HSI2. The RY element mediates repression of MAT genes, and we propose that transcriptional shutdown of the MAT program during late maturation involves inhibition of ABI3 DNA binding by dephosphorylation. Later, during seedling growth, VAL1/HSI2 family repressors silence MAT genes by binding RY elements. New Phytologist (2009)doi: 10.1111/j.1469-8137.2009.02977.x.
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