Bélair G, Mimee B, Duceppe M O, Miller S
Agriculture and Agri-Food Canada, St-Jean-sur-Richelieu, Quebec, Canada.
Canadian Food Inspection Agency, Fallowfield, Ontario, Canada.
Plant Dis. 2013 Feb;97(2):292. doi: 10.1094/PDIS-03-12-0309-PDN.
In eastern Canada, soybean, Glycine max (L.) Merr., is the most important cultivated legume species. In 2011, the provinces of Ontario and Quebec had 987,400 and 300,000 ha of soybean production, respectively. Root-lesion nematodes, Pratylenchus spp., are the most prevalent plant-parasitic nematodes in Canadian agroecosystems and can affect many crops (3). In 2011, irregular patches of stunted soybean plants were observed for the first time in a 10-ha soybean field grown on a light texture soil in St. Anicet, Quebec (45°4'50.51″N, 74°21'18.56″W). Yield reduction in damaged plots ranged from 38 to 54% when compared with asymptomatic adjacent plots. The field was sown with soybean cv. PRO 2715R (PRO Seeds of Canada, Woodstock, ON), a Roundup Ready cultivar of 2,750 CHU, at 100 kg/ha. Soil analysis revealed a uniform pH of 6.0 ± 0.2 on a gravelly sandy soil (81% sand, 10% loam, 9% clay, and 4% organic matter). On 7 October 2011, root samples were collected from 10 randomly selected damaged patches, washed under running water, and deposited in a mist chamber for a 14-day extraction period. Specimens were stored in tap water at 4°C before identification. Based on morphological characteristics, 26 individual specimens were examined (14 females, 11 males, one juvenile) and were all identified as Pratylenchus alleni Ferris, 1961 (2). Genomic DNA was extracted from individual larvae and the internal transcribed spacers (ITS) region was amplified. RFLP analysis with five restriction enzymes (CfoI, DdeI, HindIII, HpaII, and PstI) showed that the banding pattern for this species was different from those of 18 other major Pratylenchus species (4). Sequence of ITS regions of this population (GenBank Accession No. JX081545) confirmed genus identification but showed only limited homology (<85%) with the 20 Pratylenchus species available in the database at this time. Based on the morphological identification and the ITS sequence divergence with other important species, the sequence was deposited as the first P. alleni accession in GenBank. In the United States, the pathogenicity of P. alleni to soybean is well established (1). To our knowledge, this is the first report of P. alleni occurrence and damage to soybean in Canada. The outbreak of this root-lesion nematode will pose a new challenge for crop management since no registered compounds are currently available against this pest in soybean in Canada. References: (1) N. Acosta and R. B. Malek. J. Nematol. 13:6, 1981. (2) V. Ferris. Proc. Helminthological Soc. Washington 28:109, 1961. (3) J. W. Potter and A. W. McKeown. Can. J. Soil Sci. 83:289, 2003. (4) L. Waeyenberge et al. Nematol. 2:135, 2000.
在加拿大东部，大豆[Glycine max (L.) Merr.]是最重要的栽培豆科植物品种。2011年，安大略省和魁北克省的大豆种植面积分别为98.74万公顷和30万公顷。根腐线虫（Pratylenchus spp.）是加拿大农业生态系统中最常见的植物寄生线虫，会影响多种作物（3）。2011年，在魁北克省圣阿尼塞特一块10公顷、质地较轻的土壤上种植的大豆田中，首次发现了发育不良的大豆植株不规则斑块（北纬45°4′50.51″，西经74°21′18.56″）。与无症状的相邻地块相比，受损地块的产量降低了38%至54%。该田地种植的大豆品种为PRO 2715R（加拿大PRO种子公司，安大略省伍德斯托克），是一种抗农达品种，活力为2750 CHU，播种量为100千克/公顷。土壤分析显示，在砾质砂土上，土壤pH值均匀，为6.0±0.2（81%砂、10%壤土、9%黏土和4%有机质）。2011年10月7日，从10个随机选择的受损斑块采集根样本，在流水下冲洗，然后置于雾室中14天进行提取。在鉴定前，样本保存在4°C的自来水中。根据形态特征，检查了26个个体样本（14只雌虫、11只雄虫、1只幼虫），均鉴定为1961年发现的阿氏根腐线虫（Pratylenchus alleni Ferris）（2）。从单个幼虫中提取基因组DNA，并扩增内部转录间隔区（ITS）。用五种限制性内切酶（CfoI、DdeI、HindIII、HpaII和PstI）进行RFLP分析表明，该物种的条带模式与其他18种主要根腐线虫的条带模式不同（4）。该种群ITS区域的序列（GenBank登录号JX081545）证实了属的鉴定，但与当时数据库中20种根腐线虫物种的同源性仅有限（<85%）。基于形态鉴定以及与其他重要物种的ITS序列差异，该序列作为阿氏根腐线虫的首个登录序列存入GenBank。在美国，阿氏根腐线虫对大豆的致病性已得到充分证实（1）。据我们所知，这是加拿大首次报道阿氏根腐线虫的发生及其对大豆的危害。这种根腐线虫的爆发将给作物管理带来新的挑战，因为目前加拿大没有针对大豆中这种害虫的注册化合物。参考文献：（）N. 阿科斯塔和R. B. 马利克。《线虫学杂志》13:6，1981年。（2）V. 费里斯。《华盛顿蠕虫学学会会刊》28:109，1961年。（3）J. W. 波特和A. W. 麦基翁。《加拿大土壤科学杂志》83:289，2003年。（4）L. 瓦延伯格等人。《线虫学》2:135，2000年。
