Sere Y, Sorho F, Onasanya A, Jobe L, Darboe S, Bojang Y, Touray M L, Pinel-Galzi A, Fargette D
Africa Rice Center (WARDA), 01 BP 2031, Cotonou, Bénin.
National Agricultural Research Institute (NARI), PMB 526 Brikama, The Gambia.
Plant Dis. 2008 Feb;92(2):316. doi: 10.1094/PDIS-92-2-0316B.
Rice yellow mottle virus (RYMV) of the genus Sobemovirus is a major biotic constraint to rice (Oryza sativa) production in Africa. First reported in Kenya during 1966, RYMV was later found in most countries in Africa where rice is grown (1). In countries in westernmost Africa (The Gambia, Guinea-Bissau, Mauritania, and Senegal), plants with leaf yellowing and mottling symptoms were observed, but RYMV was never isolated. Rice is the staple food in The Gambia. In 2006, four samples were collected from local rice varieties in the Kuntaur Region in the center of The Gambia. Mechanical inoculation with leaf extracts from all samples caused typical yellow mottle symptoms on the susceptible rice varieties BG90-2, Bouaké 189, and IR64. RYMV was detected in the four samples collected by ELISA with polyclonal antisera (2). The 720-nt coat protein gene was amplified for each isolate by reverse-transcriptase-PCR with primers 5'-CAAAGATGGCCAGGAA-3' (sense) and 5'-CTCCCCCACCCATCCCGAGAATT-3' (antisense) (2). The RT-PCR products were directly sequenced (EMBL Accession Nos. AM765810, AM765811, AM765812, and AM765813) and then aligned using ClustalW with a pool of RYMV coat protein sequences from West African isolates (EMBL Accession Nos. AJ279905, AJ279901, AJ885137, AJ885124, and AJ279935). Phylogenetic reconstruction by maximum-likelihood with PAUP indicated that the isolates from The Gambia formed a monophyletic group with over 97% nucleotide identity and are closely related to isolates of other countries in West Africa (Burkina Faso, Côte d'Ivoire, Guinea, Mali, and Sierra-Leone) with 91 to 94% identity. Detection of RYMV in The Gambia indicates that RYMV is present in westernmost Africa, which is referred to as the 'rice belt' of Africa, and shows that RYMV is widely distributed from eastern Africa (Tanzania) to the western part of the continent. References: (1) N. K. Kouassi et al. Plant Dis. 89:124, 2005. (2) A. Pinel et al. Arch. Virol. 145:1621, 2000.
黄症病毒属的水稻黄斑驳病毒（RYMV）是非洲水稻（Oryza sativa）生产的主要生物限制因素。1966年在肯尼亚首次报道，后来在非洲大多数种植水稻的国家都发现了RYMV（1）。在最西部的非洲国家（冈比亚、几内亚比绍、毛里塔尼亚和塞内加尔），观察到有叶片发黄和斑驳症状的植株，但从未分离出RYMV。水稻是冈比亚的主食。2006年，从冈比亚中部昆陶尔地区的当地水稻品种中采集了4个样本。用所有样本的叶片提取物进行机械接种，在易感水稻品种BG90-2、布瓦凯189和IR64上引起了典型的黄斑驳症状。用多克隆抗血清通过ELISA在采集的4个样本中检测到了RYMV（2）。使用引物5'-CAAAGATGGCCAGGAA-3'（正义链）和5'-CTCCCCCACCCATCCCGAGAATT-3'（反义链）通过逆转录PCR对每个分离株的720个核苷酸的衣壳蛋白基因进行扩增（2）。RT-PCR产物直接测序（EMBL登录号：AM765810、AM765811、AM765812和AM765813），然后使用ClustalW与来自西非分离株的一组RYMV衣壳蛋白序列（EMBL登录号：AJ279905、AJ279901、AJ885137、AJ885124和AJ279935）进行比对。用PAUP通过最大似然法进行系统发育重建表明，来自冈比亚的分离株形成了一个单系群，核苷酸同一性超过97%，并且与西非其他国家（布基纳法索、科特迪瓦、几内亚、马里和塞拉利昂）的分离株密切相关，同一性为91%至94%。在冈比亚检测到RYMV表明，RYMV存在于最西部的非洲，即被称为非洲“水稻带”的地区，并且表明RYMV从东非（坦桑尼亚）到非洲大陆西部广泛分布。参考文献：（1）N.K.Kouassi等人，《植物病害》89:124，2005年。（2）A.Pinel等人，《病毒学档案》145:1621，2000年。
