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First Report of Leipotylenchus abulbosus in Iran

Leipotylenchus abulbosus (Thorne, 1949) Sher, 1974 belongs to the family Tylenchidae, subfamily Leipotylenchinae, and order Tylenchida. During the spring and autumn months of 2008 to 2010, 80 samples were collected from rhizosphere soil of symptomatic plants including wheat (Tritichum aestivum L.), beet (Beta vulgaris L.), and maize (Zea mays L.) from Meighan and Gavar regions of Markazi Province in central Iran. Plants were dwarfed and leaves were chlorotic. Diseased plants comprised ~7% of all plants in the field. Sandy loam soil was collected from roots up to 15 cm from the base of the plants. Nematodes were extracted from the soil by sieving and centrifugation (3). For species identification, nematodes were transferred to anhydrous glycerin (2) and mounted on slides by the paraffin ring method. Identification was based on morphometric and morphological characteristics of females and males. No other forms of the nematode were isolated from collected samples. L. abulbosus was found in 10% of the collected samples. The nematodes showed typical characteristics of the genus Leipotylenchus: striated and anteriorly flattened lip region, stylet without basal knobs, didelphic gonads, four incisures in lateral fields that were areolated in the posterior portion, presence of deirids and adanal caudal alae, amphid inconspicuous in males. Males contained bursa in tail. Females contained an almost straight body, tapering anteriorly from median bulb and posteriorly beyond the anus; cuticle thick, annules fine. Labial framework was moderately sclerotized. Median bulb with prominent valvular apparatus in the center, oval, occupied two-thirds of the body. Deirids were prominent and at the level of the excretory pore. Vagina a transverse slit at right angles to body axis, extending less than half width into body. Tai1 finely annulated, short, tapering to a narrow tip but becoming broader just before the terminus. Phasmids small in anterior half of the tail. Measurements of 12 females: body length = 1,377 ± 90 (1,276 to 1,469) μm; a = 39.2 ± 1.62 (36.8 to 41.1); b = 7.2 ± 0.34 (6.6 to 8.30); c = 11.1 ± 0.16 (10.7 to 11.3); V% = 52.6 ± 1.42 (50.4 to 53.8); stylet length = 17 ± 0.22 (16.6 to 18) μm; tail length = 124 ± 6.83 (116 to 137) μm); and 7 males: (body length = 1,150 ± 56.84 (1,090 to 1,246) μm; a = 39.5 ± 1.48 (37.5 to 41.5); b = 6.4 ± 0.21 (6.1 to 6.8); c = 9.5 ± 0.06 (9.4 to 9.6); T% = 55.1 ± 0.91 (54.4 to 56.20); stylet length = 17.6 ± 0.36 (17 to 18) μm; tail length = 120 ± 3.77 (115 to 129) μm) conformed to the description of L. abulbosus. L. abulbosus, originally isolated from crop plants in surveyed regions, was cultured on beet (B. vulgaris L.) in the greenhouse. Pure cultures of the nematode were inoculated on beet seedlings at the 4- to 6-leaf stage as described previously (1). Sterilized soils were inoculated with 1,000 infective mature nematodes with three replications. Infection of beet roots by the nematode resulted in leaf chlorosis and reduction in plant height. Previously, L. amiri was collected from soils associated with the roots of onion (Allium cepa L.) plants in Pakistan (4). However there have not been any reports of L. abulbosus in crop plants before. To our knowledge, this is also the first report of L. abulbosus infecting wheat, beet, and maize plants in Iran.

References: (1) K. R. Barker. Methodology 2:19, 1985. (2) A. De Grisse. Meded. Rijksfac. Landbouwwet. Gent. 34:351, 1969. (3) W. R. Jenkins. Plant Dis. Rep. 48:692, 1964. (4) M. A. Maqbool and F. Shahina. Rev. Nèmatol. 7:363, 1984.