Bulman Simon, Ridgway Hayley J, Eady Colin, Conner Anthony J
National Centre for Advanced Bio-Protection Technologies, Lincoln University, Canterbury, New Zealand.
Protist. 2007 Oct;158(4):423-33. doi: 10.1016/j.protis.2007.04.005. Epub 2007 Jul 6.
Plasmodiophora brassicae, a pathogen of Brassicaceae plants, is grouped within the eukaryotic supergroup, the Rhizaria. Although a large diversity of protists is found in the Rhizaria, genomes of organisms within the group have barely been examined. In this study, we identified DNA sequences spanning or flanking 24 P. brassicae genes, eventually sequencing close to 44 kb of genomic DNA. Evidence from this preliminary genome survey suggested that splicing is an important feature of P. brassicae gene expression; the P. brassicae genes were rich in spliceosomal introns and two mini-exons of less than 20 bp were identified. Consensus splice sites and branch-point sequences in P. brassicae introns were similar to those found in other eukaryotes. Examination of the promoter and transcription start sites of genes indicated that P. brassicae transcription is likely to begin from initiator elements rather than TATA-box containing promoters. Where neighbouring genes were confirmed, intergenic distances were short, ranging from 44 to 470 bp, but a number of larger DNA fragments containing no obvious genes were also sequenced.
芸苔根肿菌是十字花科植物的一种病原体，归类于真核生物超群根足总纲。尽管在根足总纲中发现了种类繁多的原生生物，但该类群内生物的基因组几乎未被研究过。在本研究中，我们鉴定了跨越或位于24个芸苔根肿菌基因两侧的DNA序列，最终对近44 kb的基因组DNA进行了测序。这项初步基因组调查的证据表明，剪接是芸苔根肿菌基因表达的一个重要特征；芸苔根肿菌基因富含剪接体内含子，并且鉴定出了两个长度小于20 bp的微型外显子。芸苔根肿菌内含子中的共有剪接位点和分支点序列与其他真核生物中的相似。对基因启动子和转录起始位点的研究表明，芸苔根肿菌的转录可能起始于起始元件而非含有TATA框的启动子。在确认了相邻基因的情况下，基因间距离较短，范围为44至470 bp，但也对一些不含明显基因的较大DNA片段进行了测序。
