Killiny Nabil, Jones Shelley E
Citrus Research and Education Center, Department of Plant Pathology, IFAS, University of Florida, Lake Alfred, Florida, United States of America.
PLoS One. 2018 Jan 25;13(1):e0191871. doi: 10.1371/journal.pone.0191871. eCollection 2018.
Currently, huanglongbing is the most damaging disease of citrus causing huge economic losses. The disease is caused by the Gram-negative bacterium Candidatus Liberibacter asiaticus (CLas). The pathogen is transmitted in a persistent propagative circulative manner within its vector, the Asian citrus psyllid, Diaphorina citri. Exploring the metabolic alteration in the vector may lead to a better understanding of the nutritional needs of CLas and to designing an artificial medium for culturing the pathogen. It has been shown that the nymphal stages have a greater role in transmission mainly because they feed on plants more actively than adults. In this study, we carried out an untargeted comparative metabolomic analysis for healthy and CLas-infected 4th / 5th instar nymphs. The metabolic analysis was performed using trimethylsilylation and methyl chloroformate derivatization followed by Gas Chromatography-Mass Spectrometry (GC-MS). Overall, the changes in the nymph metabolism due to the infection with CLas were more pronounced than in adults, as we previously published. Nymphs reared on CLas-infected Valencia sweet orange were higher in many metabolites, mainly those of the TCA cycle, C16 and C18 fatty acids, glucose, sucrose, L-proline, L-serine, pyroglutamic acid, saccharic acid, threonic acid and myo-inositol than those reared on healthy plants. In contrast, CLas-infected nymphs were lower in putrescine, glycine, L -phenylalanine, L -tyrosine, L -valine, and chiro-inositol. The information provided from this study may contribute in acceleration of the availability of CLas in culture and consequent screening of antibacterial compounds to discover a definitive solution for huanglongbing.
目前，黄龙病是柑橘类最具破坏性的病害，会造成巨大的经济损失。该病害由革兰氏阴性细菌亚洲韧皮杆菌（CLas）引起。病原体以持久性增殖循环的方式在其传播媒介亚洲柑橘木虱体内传播。探索传播媒介中的代谢变化可能有助于更好地了解CLas的营养需求，并设计用于培养病原体的人工培养基。研究表明，若虫阶段在传播中发挥着更大的作用，主要是因为它们比成虫更积极地取食植物。在本研究中，我们对健康的和感染CLas的4龄/5龄若虫进行了非靶向比较代谢组学分析。代谢分析采用三甲基硅烷化和氯甲酸甲酯衍生化，随后进行气相色谱-质谱联用（GC-MS）。总体而言，正如我们之前发表的那样，感染CLas导致的若虫代谢变化比成虫更为明显。以感染CLas的瓦伦西亚甜橙饲养的若虫，其许多代谢产物含量更高，主要是三羧酸循环、C16和C18脂肪酸、葡萄糖、蔗糖、L-脯氨酸、L-丝氨酸、焦谷氨酸、糖二酸、苏糖酸和肌醇的代谢产物，比以健康植物饲养的若虫含量高。相比之下，感染CLas的若虫中腐胺、甘氨酸、L-苯丙氨酸、L-酪氨酸、L-缬氨酸和手性肌醇含量较低。本研究提供的信息可能有助于加快CLas在培养基中的可得性，并因此加快抗菌化合物的筛选，以找到黄龙病的最终解决方案。
