Svanella-Dumas L, Candresse T, Maurice I, Blin V, Quaren R, Birgaentzle C
UMR 1332 Biologie du Fruit et Pathologie, INRA and Université de Bordeaux, CS 20032, 33882 Villenave d'Ornon Cedex, France.
DRAAF Alsace, CS 31009, 67070 Strasbourg Cedex, France.
Plant Dis. 2015 Mar;99(3):421. doi: 10.1094/PDIS-07-14-0763-PDN.
Plum pox virus (PPV) is the most detrimental virus in stone fruit crops (Prunus sp.). At least nine monophyletic PPV strains are recognized, three of which, PPV-D, PPV-M, and PPV-Rec, have broad distributions (2). PPV-Rec is characterized by a unique founding recombination event and has been reported mostly from Central and South-Central Europe (2). It is generally considered poorly adapted to peach, and the weak and transient symptoms it causes in the GF305 peach seedling indicator may complicate its biological detection (2). During surveys in the Alsace region of France in spring 2013, a plum orchard with trees (Prunus domestica cv. Quetsche d'Alsace 3066) showing dubious leaf symptoms possibly reminiscent of PPV infection was identified. Testing of material from this plant by ELISA (Bioreba AG, Switzerland) gave clear positive reactions, putting the overall infection rate of the orchard at 6.25%, while a second nearby orchard was found infected at a rate of 0.8%. The presence of PPV was confirmed by polymerase chain reaction (PCR) amplification using either the P1-P2 polyvalent primer pair or the P3M-P4b primer pair, which allows the specific amplification of isolates of the Rec and M strains (1). Sequencing of the 467-nt-long P3M-P4b PCR product (Genbank Accession No. KM035763), which spans the end of the NIb gene and the N-terminal hypervariable end of the coat protein gene, provided clear identification of the PPV isolate as belonging to the Rec strain, since it contained all the PPV-Rec specific mutations in the amplified region and showed 98.7 to 97.7% identity with a range of PPV Rec isolates mostly originating from the Balkans. Identification as a PPV-Rec isolate was also confirmed using a strain-specific reverse-transcription-PCR assay (3). This is, to our knowledge, the first report of the presence of PPV-Rec in France. This finding is worrisome given that PPV-Rec is considered well adapted to plum (2), the most important Prunus crop in Alsace. Further surveillance in Alsace during 2014 failed to provide evidence for the presence of PPV-Rec in other areas of the region away from the initial infection focus, which is currently undergoing eradication efforts. References: (1) T. Candresse et al. Phytopathology 88:198, 1998. (2) J. A. García et al. Mol. Plant Pathol. 15:226, 2014. (3) Z. Subr et al. Acta Virol. 48:173, 2004.
李痘病毒（PPV）是核果类作物（李属）中最具危害性的病毒。目前已识别出至少9个单系PPV毒株，其中3种，即PPV-D、PPV-M和PPV-Rec，分布广泛（2）。PPV-Rec的特征是有一次独特的奠基性重组事件，主要在中欧和中南部欧洲被报道（2）。一般认为它不太适应桃树，并且它在GF305桃树苗指示植物中引起的症状较弱且短暂，这可能会使其生物学检测变得复杂（2）。在2013年春季对法国阿尔萨斯地区的调查中，发现一个李子园里的树（欧洲李品种阿尔萨斯魁车3066）出现了可疑的叶片症状，可能提示感染了PPV。用酶联免疫吸附测定法（ELISA，瑞士Bioreba公司）检测该植株的材料得到了明确的阳性反应，该果园的总体感染率为6.25%，而附近的另一个果园感染率为0.8%。使用P1-P2多价引物对或P3M-P4b引物对进行聚合酶链反应（PCR）扩增，证实了PPV的存在，P3M-P4b引物对可特异性扩增Rec和M毒株的分离株（1）。对467个核苷酸长的P3M-P4b PCR产物（Genbank登录号KM035763）进行测序，该产物跨越NIb基因末端和外壳蛋白基因的N端高变区，明确鉴定该PPV分离株属于Rec毒株，因为它在扩增区域包含了所有PPV-Rec特异性突变，并且与一系列主要来自巴尔干地区的PPV Rec分离株的同一性为98.7%至97.7%。使用毒株特异性逆转录PCR检测法（3）也证实了其为PPV-Rec分离株。据我们所知，这是法国存在PPV-Rec的首次报道。鉴于PPV-Rec被认为很适应李子树（2），而李子树是阿尔萨斯最重要的李属作物，这一发现令人担忧。2014年在阿尔萨斯进行的进一步监测未能提供证据证明在该地区最初感染点以外的其他区域存在PPV-Rec，目前正对最初感染点进行根除工作。参考文献：（1）T. Candresse等人，《植物病理学》88:198，1998年。（2）J. A. García等人，《分子植物病理学》15:226，2014年。（3）Z. Subr等人，《病毒学学报》48:173，2004年。
