Hren Matjaz, Nikolić Petra, Rotter Ana, Blejec Andrej, Terrier Nancy, Ravnikar Maja, Dermastia Marina, Gruden Kristina
National Institute of Biology, Department of Biotechnology and Systems Biology, Vecna pot 111, 1000 Ljubljana, Slovenia.
BMC Genomics. 2009 Oct 2;10:460. doi: 10.1186/1471-2164-10-460.
Phytoplasmas are bacteria without cell walls from the class Mollicutes. They are obligate intracellular plant pathogens which cause diseases in hundreds of economically important plants including the grapevine (Vitis vinifera). Knowledge of their biology and the mechanisms of their interactions with hosts is largely unknown because they are uncultivable and experimentally inaccessible in their hosts. We detail here the global transcriptional profiling in grapevine responses to phytoplasmas. The gene expression patterns were followed in leaf midribs of grapevine cv. 'Chardonnay' naturally infected with a phytoplasma from the stolbur group 16SrXII-A, which is associated with the grapevine yellows disease 'Bois noir'.
We established an on field experimental system in a productive vineyard that allowed application of molecular tools in a plant natural environment. Global transcription profiles of infected samples were compared with the healthy ones using microarray datasets and metabolic pathway analysis software (MapMan). The two-year-long experiment revealed that plant genes involved in primary and secondary metabolic pathways were changed in response to infection and that these changes might support phytoplasma nutrition. A hypothesis that phytoplasmas interact with the plant carbohydrate metabolism was proven and some possibilities how the products of this pathway might be utilized by phytoplasmas are discussed. In addition, several photosynthetic genes were largely down-regulated in infected plants, whereas defense genes from the metabolic pathway leading to formation of flavonoids and some PR proteins were significantly induced. Few other genes involved in defense-signaling were differentially expressed in healthy and infected plants. A set of 17 selected genes from several differentially expressed pathways was additionally analyzed with quantitative real-time PCR and confirmed to be suitable for a reliable classification of infected plants and for the characterization of susceptibility features in the field conditions.
This study revealed some fundamental aspects of grapevine interactions with the stolbur 'Bois noir' phytoplasma in particular and some plant interactions with phytoplasmas in general. In addition, the results of the study will likely have an impact on grape improvement by yielding marker genes that can be used in new diagnostic assays for phytoplasmas or by identifying candidate genes that contribute to the improved properties of grape.
植原体是柔膜菌纲的无细胞壁细菌。它们是专性细胞内植物病原体，可在包括葡萄（葡萄属）在内的数百种经济上重要的植物中引发疾病。由于它们不可培养且在宿主中难以进行实验研究，因此对其生物学特性及其与宿主相互作用机制的了解十分有限。在此，我们详细阐述了葡萄对植原体反应的全基因组转录谱分析。我们追踪了葡萄品种“霞多丽”叶片中脉的基因表达模式，该葡萄自然感染了来自 stolbur 组 16SrXII - A 的植原体，这种植原体与葡萄黄化病“黑木”相关。
我们在一个生产性葡萄园建立了田间实验系统，该系统允许在植物自然环境中应用分子工具。使用微阵列数据集和代谢途径分析软件（MapMan）将感染样本的全基因组转录谱与健康样本进行比较。为期两年的实验表明，参与初级和次级代谢途径的植物基因因感染而发生变化，这些变化可能为植原体提供营养支持。一个关于植原体与植物碳水化合物代谢相互作用的假设得到了证实，并讨论了该途径的产物可能被植原体利用的一些方式。此外，感染植物中的几个光合基因大幅下调，而导致黄酮类化合物形成的代谢途径中的防御基因和一些病程相关蛋白则被显著诱导。在健康植物和感染植物中，很少有其他参与防御信号传导的基因差异表达。另外，对来自几个差异表达途径的一组 17 个选定基因进行了定量实时 PCR 分析，证实它们适用于对感染植物进行可靠分类以及在田间条件下表征易感性特征。
本研究揭示了葡萄与 stolbur“黑木”植原体相互作用的一些基本方面，特别是以及一些植物与植原体相互作用的一般情况。此外，该研究结果可能会对葡萄改良产生影响，通过产生可用于新的植原体诊断检测的标记基因，或通过鉴定有助于改善葡萄特性的候选基因。
