Pieretti Isabelle, Pesic Alexander, Petras Daniel, Royer Monique, Süssmuth Roderich D, Cociancich Stéphane
UMR BGPI , Cirad, Montpellier, France.
Institut für Chemie, Technische Universität Berlin , Berlin, Germany.
Front Plant Sci. 2015 Apr 24;6:289. doi: 10.3389/fpls.2015.00289. eCollection 2015.
Xanthomonas albilineans causes leaf scald, a lethal disease of sugarcane. Compared to other species of Xanthomonas, X. albilineans exhibits distinctive pathogenic mechanisms, ecology and taxonomy. Its genome, which has experienced significant erosion, has unique genomic features. It lacks two loci required for pathogenicity in other plant pathogenic species of Xanthomonas: the xanthan gum biosynthesis and the Hrp-T3SS (hypersensitive response and pathogenicity-type three secretion system) gene clusters. Instead, X. albilineans harbors in its genome an SPI-1 (Salmonella pathogenicity island-1) T3SS gene cluster usually found in animal pathogens. X. albilineans produces a potent DNA gyrase inhibitor called albicidin, which blocks chloroplast differentiation, resulting in the characteristic white foliar stripe symptoms. The antibacterial activity of albicidin also confers on X. albilineans a competitive advantage against rival bacteria during sugarcane colonization. Recent chemical studies have uncovered the unique structure of albicidin and allowed us to partially elucidate its fascinating biosynthesis apparatus, which involves an enigmatic hybrid PKS/NRPS (polyketide synthase/non-ribosomal peptide synthetase) machinery.
白叶枯病菌会引发甘蔗叶烧病，这是一种致命的甘蔗病害。与黄单胞菌属的其他物种相比，白叶枯病菌具有独特的致病机制、生态学特征和分类学特点。其基因组经历了显著的侵蚀，具有独特的基因组特征。它缺少黄单胞菌属其他植物致病物种致病所需的两个基因座：黄原胶生物合成基因座和Hrp-T3SS（过敏反应和致病性三型分泌系统）基因簇。相反，白叶枯病菌在其基因组中含有一个通常在动物病原体中发现的SPI-1（沙门氏菌致病岛-1）三型分泌系统基因簇。白叶枯病菌会产生一种名为杀稻菌素的强效DNA促旋酶抑制剂，它会阻断叶绿体分化，从而导致特征性的白色叶条症状。杀稻菌素的抗菌活性也使白叶枯病菌在甘蔗定殖过程中相对于竞争细菌具有竞争优势。最近的化学研究揭示了杀稻菌素的独特结构，并使我们能够部分阐明其迷人的生物合成机制，该机制涉及一种神秘的混合聚酮合酶/非核糖体肽合成酶机制。
