Huanglongbing (HLB) is the most damaging disease in citrus. It is caused by the putative bacterium, “ Candidatus Liberibacter asiaticus” and is transmitted by the Asian citrus psyllid, Diaphorina citri . Unfortunately, no cure has been found or effective control strategy established for the combat of this disease. Citrus tristeza virus (CTV) was employed successfully for virus induced gene silencing system (VIGS). Previous studies reported the successful use of citrus mediated CTV-based VIGS against D. citri ; however, the system was not tested in “ Ca. L. asiaticus”-infected citrus. In addition, very little is known about the interaction between CTV and “ Ca. L. asiaticus”. Herein, this relationship was explored by infiltrating citrus plants with CTV carrying a truncated phytoene desaturase gene ( pds ) as a reporter gene. Repressing pds in citrus causes a photo-bleached leaf phenotype. These plants were then graft-inoculated with budwood from “ Ca. L. asiaticus”-infected plants. A strong photo-bleaching phenotype indicates that the CTV is present and actively replicating, whereas a weak leaf phenotype indicates reduced or absent virus titer. After infection with “ Ca. L. asiaticus”, the leaf-bleaching phenotype gradually became reduced, and the HLB symptoms increased. After three years, the photo-bleaching phenotype was completely absent, while HLB symptoms were fully pronounced. Subsequently, CTV titer was dramatically reduced while “ Ca. L. asiaticus” titer increased. In addition, the gene expression of pds was increased indicating a deficit in the RNA interference. On the other hand, enhancing the nutrition of CTV- t PDS plants magnified the photo-bleaching phenotype and diminished the symptoms in HLB-infected plants. Taken together, combining enhanced nutritional programs with the use of CTV as a VIGS vector to target D. citri by citrus mediated RNAi may prolong its efficacy in the fight against HLB. The long-term success of CTV-based VIGS technology is contingent on the balance of power favoring the CTV, rather than the HLB bacterial pathogen, “ Ca. L. asiaticus”.

中文翻译：

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Citrus tristeza病毒作为载体在受黄龙病影响的柑橘中病毒诱导基因沉默的功效

黄龙病（HLB）是柑橘中危害最大的病害。它由假定的细菌“Candidatus Liberibacter asiaticus”引起，并由亚洲柑橘木虱（Diaphorina citri）传播。不幸的是，没有找到治愈方法或建立有效的控制策略来对抗这种疾病。Citrus tristeza 病毒（CTV）被成功用于病毒诱导的基因沉默系统（VIGS）。先前的研究报告成功使用柑橘介导的基于 CTV 的 VIGS 来对抗 D. citri ；然而，该系统并未在“Ca”中进行测试。L. asiaticus”感染的柑橘。此外，人们对 CTV 与“Ca”之间的相互作用知之甚少。L. asiaticus”。在本文中，通过将带有截短的八氢番茄红素去饱和酶基因 ( pds ) 作为报告基因的 CTV 渗透到柑橘植物中来探索这种关系。抑制柑橘中的 pds 会导致光漂白叶表型。然后用来自“Ca”的芽木嫁接这些植物。L. asiaticus”感染的植物。强光漂白表型表明 CTV 存在并积极复制，而弱叶表型表明病毒滴度降低或不存在。感染“Ca. L. asiaticus”，叶片漂白表型逐渐减少，HLB症状加重。三年后，光漂白表型完全消失，而 HLB 症状完全明显。随后，CTV 滴度显着降低，而“Ca. L. asiaticus”滴度增加。此外，pds 的基因表达增加，表明 RNA 干扰不足。另一方面，增强 CTV-t PDS 植物的营养会放大光漂白表型并减少 HLB 感染植物的症状。总之，将增强的营养计划与使用 CTV 作为 VIGS 载体通过柑橘介导的 RNAi 靶向 D. citri 相结合可能会延长其对抗 HLB 的功效。基于 CTV 的 VIGS 技术的长期成功取决于有利于 CTV 而不是 HLB 细菌病原体“Ca. L. asiaticus”。而不是 HLB 细菌病原体，“Ca。L. asiaticus”。而不是 HLB 细菌病原体，“Ca。L. asiaticus”。