Department of Food Science & Technology, University of California-Davis, Davis, CA 95616.
Contained Research Facility, University of California-Davis, Davis, CA 95616.
Phytopathology. 2022 Jan;112(1):197-204. doi: 10.1094/PHYTO-06-21-0240-FI. Epub 2022 Jan 14.
' Liberibacter asiaticus' is associated with the devastating citrus disease Huanglongbing (HLB). It is transmitted by grafting infected material to healthy plants and by the feeding of the Asian citrus psyllid (). Previously, we demonstrated that a metabolomics approach using proton-nuclear magnetic resonance spectroscopy discriminates healthy from diseased plants via grafting. This work assessed the capability of this technology in discriminating healthy and diseased plants when the bacterium is vectored by psyllids. One-year-old greenhouse-grown 'Lisbon' lemon trees were exposed to either carrier psyllids (exposed, = 10), or psyllids that were free of ' Liberibacter asiaticus' (control, = 6). Leaf metabolites were tracked for 1 year and disease diagnosis was made using quantitative PCR. Overall, 31 water-soluble metabolites were quantified in leaves, including four sugars and 12 amino acids. Analysis via nonmetric multidimensional scaling and principal component analysis revealed significant differences between the leaf metabolome of control versus infected trees beginning at 8 weeks postexposure, including alterations in glucose and quinic acid concentrations. These findings provide a longitudinal overview of the metabolic effects of HLB during the early phases of disease, and confirm previous experimental work demonstrating that infection elicits changes in the leaf metabolome that enables discrimination between healthy and infected plants. Here we demonstrate that the mode of inoculation (i.e., graft versus psyllid) results in a similar pathology.
“亚洲韧皮杆菌”与毁灭性的柑橘黄龙病（HLB）有关。它通过将感染的材料嫁接至健康植物以及亚洲柑橘木虱（）的取食进行传播。此前，我们通过质子核磁共振波谱的代谢组学方法证明，通过嫁接可以区分健康和患病的植物。本研究评估了该技术在韧皮杆菌通过木虱传播时区分健康和患病植物的能力。将 1 年生温室生长的‘里斯本’柠檬树暴露于携带韧皮杆菌的木虱（暴露组，n=10）或不携带“亚洲韧皮杆菌”的木虱（对照组，n=6）下。在 1 年内跟踪叶片代谢物，并通过定量 PCR 进行疾病诊断。总体而言，在叶片中定量了 31 种水溶性代谢物，包括 4 种糖和 12 种氨基酸。非度量多维标度和主成分分析表明，在暴露后 8 周开始，对照与感染树的叶片代谢组之间存在显著差异，包括葡萄糖和奎宁酸浓度的改变。这些发现提供了 HLB 在疾病早期阶段的代谢影响的纵向概述，并证实了先前的实验工作，证明感染会引发叶片代谢组的变化，从而能够区分健康和感染的植物。在这里，我们证明了接种方式（即嫁接与木虱）会导致类似的病理变化。
