Department of Agricultural and Environmental Sciences, University of Milan, 20133 Milan, Italy.
Department of Plant Protection, Faculty of Agriculture, University of Jiroft, Jiroft 7867161167, Iran.
Int J Mol Sci. 2018 Jun 20;19(6):1817. doi: 10.3390/ijms19061817.
Citrus Decline Disease was recently reported to affect several citrus species in Iran when grafted on a local rootstock variety, Bakraee. Preliminary studies found “ Phytoplasma aurantifoliae” and “ Liberibacter asiaticus” as putative etiological agents, but were not ultimately able to determine which one, or if an association of both, were causing the disease. The current study has the aim of characterizing the microbiota of citrus plants that are either asymptomatic, showing early symptoms, or showing late symptoms through amplification of the V1–V3 region of 16S rRNA gene using an Illumina sequencer in order to (i) clarify the etiology of the disease, and (ii) describe the microbiota associated to different symptom stages. Our results suggest that liberibacter may be the main pathogen causing Citrus Decline Disease, but cannot rule out the possibility of phytoplasma being involved as well. The characterization of microbiota shows that the leaves show only two kinds of communities, either symptomatic or asymptomatic, while roots show clear distinction between early and late symptoms. These results could lead to the identification of bacteria that are related to successful plant defense response and, therefore, to immunity to the Citrus Decline Disease.
柑橘衰退病最近被报道在伊朗的几种柑橘品种上发生，这些品种被嫁接到当地的一种砧木品种 Bakraee 上。初步研究发现“黄化植原体”和“亚洲韧皮杆菌”可能是致病因子，但最终未能确定是哪一种，或者是否存在两者的关联导致了这种疾病。本研究旨在通过 Illumina 测序仪扩增 16S rRNA 基因的 V1-V3 区，对表现无症状、早期症状或晚期症状的柑橘植物的微生物组进行特征描述，目的是：(i) 阐明疾病的病因，(ii) 描述与不同症状阶段相关的微生物组。我们的结果表明，韧皮杆菌可能是引起柑橘衰退病的主要病原体，但不能排除植原体也参与其中的可能性。微生物组的特征表明，叶片只显示两种群落，要么是有症状的，要么是无症状的，而根部则在早期和晚期症状之间有明显的区别。这些结果可能会导致鉴定出与成功的植物防御反应相关的细菌，从而对柑橘衰退病产生免疫力。
