Collemare Jérôme, Griffiths Scott, Iida Yuichiro, Karimi Jashni Mansoor, Battaglia Evy, Cox Russell J, de Wit Pierre J G M
Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands ; Centre for Biosystems Genomics, Wageningen, The Netherlands.
Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands.
PLoS One. 2014 Jan 17;9(1):e85877. doi: 10.1371/journal.pone.0085877. eCollection 2014.
Cladosporium fulvum is a biotrophic fungal pathogen that causes leaf mould of tomato. Analysis of its genome suggested a high potential for production of secondary metabolites (SM), which might be harmful to plants and animals. Here, we have analysed in detail the predicted SM gene clusters of C. fulvum employing phylogenetic and comparative genomic approaches. Expression of the SM core genes was measured by RT-qrtPCR and produced SMs were determined by LC-MS and NMR analyses. The genome of C. fulvum contains six gene clusters that are conserved in other fungal species, which have undergone rearrangements and gene losses associated with the presence of transposable elements. Although being a biotroph, C. fulvum has the potential to produce elsinochrome and cercosporin toxins. However, the corresponding core genes are not expressed during infection of tomato. Only two core genes, PKS6 and NPS9, show high expression in planta, but both are significantly down regulated during colonization of the mesophyll tissue. In vitro SM profiling detected only one major compound that was identified as cladofulvin. PKS6 is likely involved in the production of this pigment because it is the only core gene significantly expressed under these conditions. Cladofulvin does not cause necrosis on Solanaceae plants and does not show any antimicrobial activity. In contrast to other biotrophic fungi that have a reduced SM production capacity, our studies on C. fulvum suggest that down-regulation of SM biosynthetic pathways might represent another mechanism associated with a biotrophic lifestyle.
番茄枝孢是一种引起番茄叶霉病的活体营养型真菌病原体。对其基因组的分析表明，它具有产生次生代谢产物（SM）的巨大潜力，这些次生代谢产物可能对植物和动物有害。在这里，我们采用系统发育和比较基因组学方法，对番茄枝孢预测的SM基因簇进行了详细分析。通过RT-qrtPCR测定SM核心基因的表达，并通过LC-MS和NMR分析确定产生的SM。番茄枝孢的基因组包含六个在其他真菌物种中保守的基因簇，这些基因簇经历了与转座子存在相关的重排和基因丢失。尽管番茄枝孢是一种活体营养型真菌，但它有产生链格孢色素和尾孢菌素毒素的潜力。然而，在感染番茄的过程中，相应的核心基因并不表达。只有两个核心基因PKS6和NPS9在植物中高表达，但在叶肉组织定殖过程中均显著下调。体外SM谱分析仅检测到一种主要化合物，鉴定为枝孢菌素。PKS6可能参与了这种色素的产生，因为它是在这些条件下唯一显著表达的核心基因。枝孢菌素不会引起茄科植物坏死，也没有任何抗菌活性。与其他活体营养型真菌相比，其产生SM的能力有所下降，我们对番茄枝孢的研究表明，SM生物合成途径的下调可能代表了与活体营养型生活方式相关的另一种机制。
