Brito J A, Han H, Stanley J D, Hao M, Dickson D W
Division of Plant Industry, Gainesville, FL 32614-7100.
Division of Forest Insect Pests and Diseases, Korea Forest Research Institute, Seoul, Republic of Korea, 130-712.
Plant Dis. 2013 Jan;97(1):151. doi: 10.1094/PDIS-02-12-0201-PDN.
Roots of laurel oak (Quercus laurifolia Michx.), member of the family Fagaceae, were found to be heavily galled by the pecan root-knot nematode, Meloidogyne partityla, in two separate home gardens between 2010 and 2012, in Alachua Co., FL. Distinct round galls were observed on secondary and tertiary roots. Internally, root-knot nematode females were clearly visible when the roots were thinly sliced and egg masses were seen protruding from the root surfaces. The nematode species identification was performed using morphology of the male stylet, selected characters of the second-stage juveniles (J2), female perineal patterns, and esterase (EST) and malate dehydrogenase (Mdh) isozyme phenotypes. Morphology of perineal patterns of females, body, stylet, and tail length of the J2 and males all matched those of the original description of M. partityla (2). A swollen deeply grooved rectum was observed in the J2. The male stylet had a blunt tip with a prominent thickening at the junction between the cone and shaft. The stylet knobs of males and females were bipartite, each incised by a deep medium longitudinal groove (2). The isozyme phenotypes (EST = Mp3; Mdh = N1a) were consistent with those previously reported for M. partityla from Florida (1). Mitochondrial DNA (mtDNA) (3) and ribosomal internal transcriber spacer (ITS) DNA (4) of females were amplified to further confirm the nematode species identification. The mtDNA amplification using the C2F3/1108 primer set (3) and the ITS amplification using a recently available M. partityla specific primer set (4) produced fragments of approximately 530 bp and 550 bp, respectively. These were consistent with those already reported for this nematode species. This first report of a plant host for the pecan root-knot nematode outside of the family Juglandaceae indicates that the nematode may have migrated from Quercus species to pecan trees during the period when orchards were being established in Florida. To our knowledge, this is the first report of the pecan root-knot nematode infecting laurel oak. References: (1) J. A. Brito et al. Nematology 10:757, 2008. (2) Kleynhans, K. P. N. Phytophylatica 18:103, 1986. (3) T. O. Powers et al., J. Nematol. 37:226, 2005. (4) R. A. Stamler. M. S. thesis, New Mexico State University, Las Cruces, 2009.
在2010年至2012年间，佛罗里达州阿拉楚阿县的两个独立家庭花园中，人们发现壳斗科成员月桂叶栎（Quercus laurifolia Michx.）的根系被山核桃根结线虫（Meloidogyne partityla）严重侵害。在次生根和三级根上观察到明显的圆形虫瘿。从内部看，将根切成薄片时，根结线虫雌虫清晰可见，并且能看到卵块从根表面突出。线虫种类鉴定是利用雄虫口针的形态、二期幼虫（J2）的选定特征、雌虫会阴花纹以及酯酶（EST）和苹果酸脱氢酶（Mdh）同工酶表型进行的。雌虫会阴花纹的形态、J2和雄虫的身体、口针及尾长均与M. partityla的原始描述相符（2）。在J2中观察到直肠肿胀且有深深的沟纹。雄虫口针尖端钝圆，在圆锥部和杆部的交界处有明显增厚。雄虫和雌虫的口针瘤均为二分，各被一条深的中纵沟切开（2）。同工酶表型（EST = Mp3；Mdh = N1a）与先前佛罗里达州报道的M. partityla的表型一致（1）。对雌虫的线粒体DNA（mtDNA）（3）和核糖体内部转录间隔区（ITS）DNA（4）进行扩增，以进一步确认线虫种类鉴定。使用C2F3/1108引物组进行的mtDNA扩增（3）以及使用最近可用的M. partityla特异性引物组进行的ITS扩增（4）分别产生了约530 bp和550 bp的片段。这些与该线虫种类已报道的片段一致。山核桃根结线虫在胡桃科以外的植物宿主上的首次报道表明，在佛罗里达州果园建立期间，该线虫可能已从栎属植物迁移到山核桃树上。据我们所知，这是山核桃根结线虫感染月桂叶栎的首次报道。参考文献：（1）J. A. Brito等人，《线虫学》10：757，2008年。（2）Kleynhans，K. P. N.，《植物病理学》18：103，1986年。（3）T. O. Powers等人，《线虫学杂志》37：226，2005年。（4）R. A. Stamler，硕士论文，新墨西哥州立大学，拉斯克鲁塞斯，2009年。
