Fu M Y, Wang H F, Chen M C
Institute of Environment and Plant Protection, Hainan Academy of Agricultural Sciences, Hainan Key Laboratory for Control of Plant Diseases and Insect Pests, Haikou, 571100, China.
Plant Dis. 2013 Nov;97(11):1518. doi: 10.1094/PDIS-10-12-0914-PDN.
Noni (Morinda citrifolia) is an important medicinal plant and its fruit and root are of high value. In recent years, noni has been cultivated widely on Hainan Island, China. A survey of eight commercial noni fields in four counties found that most fields had plants with symptoms consistent with damage caused by root-knot nematodes. Above-ground symptoms included reduced vigor, plant stunting, and chlorosis. Affected roots were galled, swollen, cracked, and rotten. Fruit loss associated with diseased plants was quantified as 85%. In each field, three samples were taken consisting of 15 cm wide × 20 cm deep soil (containing roots). The nematode population was extracted and quantified according to Barker (1). Nematodes were found in all soil and root samples with population densities ranging from 450 to 835 eggs and second-stage juveniles (J2s) per 200 g subsample of soil, and 685 to 985 eggs and J2s per 10 g sub-sample of fresh roots. Three single egg masses were respectively hand-picked from one sample of diseased noni roots and inoculated onto tomato plants grown with sterilized soil at 20 to 28°C in the greenhouse. After 8 weeks, nematodes were extracted from the roots of tomato plants and identified by morphology, enzyme analysis, and molecular characterization. Morphology of the female perineal patterns showed a low dorsal arch with large lateral lines separating the striae of the dorsal and ventral sectors, leading to the tail terminus; and wavy, coarse striae with forking at lateral lines and short irregular striae near the lateral lines. Enzyme analysis of the esterase phenotype was also typical of the A1 phenotype in M. arenaria. Based on the perineal pattern and esterase phenotype, the Meloidogyne species was identified as M. arenaria (Est A1) (3). Total genomic DNA was extracted from ca. 10 μl of packed second-stage juveniles (J2s) using the method of Cenis (2). The primers C2F3 (5'-GGTCAATGTTCAGAAATTTGTGG-3') and 1108 (5'-TACCTTTGACCAATCACGCT-3') (4) was used to amplify the intergenic region between COII and LrRNA genes of the mtDNA and an amplification product (1,700 bp) was obtained, similar to M. hispanica, M. incognita, and M. javanica. Root-knot nematodes (Meloidogyne spp.) have been reported to be cause disease on noni in Hawaii. However, to our knowledge, this is the first report of M. arenaria (Est A1) infecting noni in China. References: (1) K. R. Barker. Pp. 19 in: An Advanced Treatise on Meloidogyne. Vol. II, Methodology. K. R. Barker et al. eds. North Carolina State University Graphics, Raleigh, 1985. (2) J. L. Cenis. Phytopathology 83:76,1993. (3) P. E. Esbenshade and A. C. Triantaphyllou. J. Nematol. 17:6,1990. (4) T. O. Power and T. S. Harris J. Nematol. 25:1,1993.
诺丽（海巴戟）是一种重要的药用植物，其果实和根部具有很高的价值。近年来，诺丽在中国海南岛得到了广泛种植。对四个县的八个商业诺丽种植园进行的一项调查发现，大多数种植园中的植株都出现了与根结线虫造成的损害相一致的症状。地上部分的症状包括活力下降、植株矮化和黄化。受影响的根部出现虫瘿、肿胀、开裂和腐烂。与患病植株相关的果实损失经量化为85%。在每个种植园中，采集了三个样本，每个样本为宽15厘米×深20厘米的土壤（包含根部）。根据巴克（1）的方法提取并量化线虫数量。在所有土壤和根部样本中均发现了线虫，土壤每200克子样本中线虫种群密度为450至835个卵和二期幼虫（J2），新鲜根部每10克子样本中线虫种群密度为685至985个卵和J2。从一个患病诺丽根部样本中分别手工挑选出三个单个卵块，接种到在温室中20至28°C下用灭菌土壤种植的番茄植株上。8周后，从番茄植株根部提取线虫并通过形态学、酶分析和分子特征进行鉴定。雌虫会阴花纹的形态显示背弓较低，有粗大的侧线将背区和腹区的条纹分开，延伸至尾端；条纹呈波浪状、粗糙，在侧线处有分叉，靠近侧线处有短的不规则条纹。酯酶表型的酶分析也显示为南方根结线虫的典型A1表型。根据会阴花纹和酯酶表型，将根结线虫种类鉴定为南方根结线虫（Est A1）（3）。使用塞尼斯（2）的方法从约10微升浓缩的二期幼虫（J2）中提取总基因组DNA。使用引物C2F3（5'-GGTCAATGTTCAGAAATTTGTGG-3'）和1108（5'-TACCTTTGACCAATCACGCT-3'）（4）扩增线粒体DNA中COII和LrRNA基因之间的基因间隔区，获得了一个1700碱基对的扩增产物，与西班牙根结线虫、爪哇根结线虫和南方根结线虫相似。据报道，根结线虫（Meloidogyne spp.）在夏威夷会导致诺丽患病。然而，据我们所知，这是中国关于南方根结线虫（Est A1）感染诺丽的首次报道。参考文献：（1）K. R. 巴克。载于：《根结线虫高级论文集》第二卷，方法学。K. R. 巴克等人编。北卡罗来纳州立大学图形部，罗利，1985年，第19页。（2）J. L. 塞尼斯。植物病理学83:76，1993年。（3）P. E. 埃斯本沙德和A. C. 特里安塔菲洛。线虫学杂志17:6，1990年。（4）T. O. 鲍尔和T. S. 哈里斯。线虫学杂志25:1，1993年。
