First Report of Meloidogyne enterolobii on Arrowroot in China

The rhizome of arrowroot (Maranta arundinacea L.) is used as a source of edible starch in many tropical/subtropical areas. In July 2009, cultivated arrowroot plants in a field in Haikou, Hainan Province, China were observed to be exhibiting symptoms of decline, including stunting and yellowing. Roots of affected plants were found to have severe root galling similar to that caused by root-knot nematodes. Meloidogyne sp. females were dissected from the galls. Morphological characteristics of the females fit the description of M. enterolobii Yang & Eisenback (4). The perineal patterns were variable, with moderately high to high dorsal arch and mostly lacking lateral lines, but when present, the lines were not conspicuous, similar to those in the original description.(4). For further confirmation of species identity, isoenzyme patterns of malate dehydrogenase (Mdh) and esterase (Est) phenotypes were analyzed and partial sequences of mtDNA were obtained. Enzyme electrophoresis showed that the phenotypes of Mdh and Est were N1a and VS1-S1 respectively, which were consistent with those of M. enterolobii (1). Amplification and sequencing of the mtDNA between COII and the lRNA gene was accomplished with primers C2F3 (5'-GGTCAATGTTCAGAAATTTGTGG-3') and 1108 (5'-TACCTTTGACCAATCACGCT-3') (2). A DNA fragment of 705 bp was obtained and the sequence (GenBank Accession No. GQ870255) was compared with those in GenBank. A BLAST search indicated the sequence was 100% identical to the sequences of M. mayaguensis (GenBank Accession Nos. AY446969 and AY446970), a synonym of M. enterolobii (3). On the basis of these results, the root-knot nematodes isolated from arrowroot in Hainan were confirmed as M. enterolobii. This species has a high reproduction rate and a wide host range; moreover, it can induce severe galling and is able to overcome the resistance gene Mi-1 in tomato and pepper (4). M. enterolobii has become increasingly important because it has been found in many countries on diverse hosts. In China in recent years, the nematode has been reported on approximately 20 plant species belonging to five families, including Fabaceae, Cucurbitaceae, Solanaceae, Myrtaceae, and Annonaceae. To our knowledge, this is the first record of M. enterolobii parasitizing a plant (i.e., arrowroot) in the family Marantaceae in China. References: (1) P. R. Esbenshade and A. C. Triantaphyllou. J. Nematol. 17:6, 1985. (2) T. O. Powers and T. S. Harris. J. Nematol. 25:1, 1993. (3) J. Xu et al. Eur. J. Plant Pathol. 110:309, 2004. (4) B. Yang and J. D. Eisenback. J. Nematol. 15:381, 1983.