Ramos-González Pedro Luis, Chabi-Jesus Camila, Guerra-Peraza Orlene, Tassi Aline Daniele, Kitajima Elliot Watanabe, Harakava Ricardo, Salaroli Renato Barbosa, Freitas-Astúa Juliana
First, second, third, sixth, and eighth authors: Lab. Bioquímica Fitopatológica, Instituto Biológico, São Paulo 04014-002, Brazil; second, fourth, fifth, and seventh authors: Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo, Piracicaba, São Paulo 13418-900, Brazil; third author: Citrus Research & Education Center, University of Florida, Lake Alfred 33850; and eighth author: Embrapa Mandioca e Fruticultura, Cruz das Almas, Bahia 44380-000, Brazil.
Phytopathology. 2017 Aug;107(8):963-976. doi: 10.1094/PHYTO-02-17-0042-R. Epub 2017 May 22.
Citrus leprosis (CL) is a viral disease endemic to the Western Hemisphere that produces local necrotic and chlorotic lesions on leaves, branches, and fruit and causes serious yield reduction in citrus orchards. Samples of sweet orange (Citrus × sinensis) trees showing CL symptoms were collected during a survey in noncommercial citrus areas in the southeast region of Brazil in 2013 to 2016. Transmission electron microscopy analyses of foliar lesions confirmed the presence of rod-like viral particles commonly associated with CL in the nucleus and cytoplasm of infected cells. However, every attempt to identify these particles by reverse-transcription polymerase chain reaction tests failed, even though all described primers for the detection of known CL-causing cileviruses and dichorhaviruses were used. Next-generation sequencing of total RNA extracts from three symptomatic samples revealed the genome of distinct, although highly related (>92% nucleotide sequence identity), viruses whose genetic organization is similar to that of dichorhaviruses. The genome sequence of these viruses showed <62% nucleotide sequence identity with those of orchid fleck virus and coffee ringspot virus. Globally, the deduced amino acid sequences of the open reading frames they encode share 32.7 to 63.8% identity with the proteins of the dichorhavirids. Mites collected from both the naturally infected citrus trees and those used for the transmission of one of the characterized isolates to Arabidopsis plants were anatomically recognized as Brevipalpus phoenicis sensu stricto. Molecular and biological features indicate that the identified viruses belong to a new species of CL-associated dichorhavirus, which we propose to call Citrus leprosis N dichorhavirus. Our results, while emphasizing the increasing diversity of viruses causing CL disease, lead to a reevaluation of the nomenclature of those viruses assigned to the genus Dichorhavirus. In this regard, a comprehensive discussion is presented.
柑橘麻风病（CL）是一种西半球特有的病毒性疾病，会在叶片、枝条和果实上产生局部坏死和褪绿病斑，导致柑橘园严重减产。2013年至2016年期间，在巴西东南部非商业柑橘种植区的一次调查中，采集了表现出CL症状的甜橙（Citrus × sinensis）树样本。对叶片病斑进行的透射电子显微镜分析证实，在受感染细胞的细胞核和细胞质中存在通常与CL相关的杆状病毒颗粒。然而，尽管使用了所有描述的用于检测已知引起CL的环斑病毒属病毒和二分纤细病毒属病毒的引物，但通过逆转录聚合酶链反应试验鉴定这些颗粒的每一次尝试均告失败。对三个有症状样本的总RNA提取物进行的二代测序揭示了不同但高度相关（核苷酸序列同一性>92%）的病毒基因组，其基因结构与二分纤细病毒属病毒相似。这些病毒的基因组序列与兰花斑点病毒和咖啡环斑病毒的基因组序列的核苷酸序列同一性<62%。在全球范围内，它们编码的开放阅读框的推导氨基酸序列与二分纤细病毒科病毒的蛋白质具有32.7%至63.8%的同一性。从自然感染的柑橘树上以及用于将一种特征化分离株传播到拟南芥植株的柑橘树上采集的螨类，经解剖学鉴定为狭义的红叶短须螨。分子和生物学特征表明，所鉴定的病毒属于一种与CL相关的二分纤细病毒新种，我们提议将其命名为柑橘麻风病N二分纤细病毒。我们的结果在强调引起CL疾病的病毒多样性不断增加的同时，导致对那些归入二分纤细病毒属的病毒的命名法进行重新评估。在这方面，本文进行了全面的讨论。
