Identification of Four Species of the Tylenchidae Family in Potato Fields of Friedan Region in Isfahan Province

Introduction: The potato is one of the most dicotyledonous human nutrition, and this product is in fifth grade under the cultivation area. Isfahan province is one of the most strategically located areas for the production of potato. Potato suffered by several diseases that directly or indirectly caused by number of pest, including plant parasitic nematodes. The most important damage and parasitic nematodes in potato fields are cyst forming nematode Globodera rostochiensis and G. pallida , root-knot nematodes Meloidogyne spp, tuber and stem rot nematodes Ditylenchus destructor and  D.dipsaci and root lesion nematodes Pratylenchus spp, respectively. However, many other species are found associated with potato, such as Belonolaimus longicaudatus, Xiphinema spp., Rotylenchulus spp., Radopholus similis, Logidorus spp. Most of these have not been property assessed. There are no specific above ground symptoms of diagnostic value associated with potato nematode infections. However, root injury causes stress and reduces uptake of water and nutrients which in turn causes stunting, yellowing and other discoloration and wilting of the foliage under drought conditions. Karimipoor (2012) identified and determined the density population internal parasitic nematodes in the potato fields of Isfahan. Also, Erfani Porghasemi et al. (2011) identified plant parasitic nematodes in potato fields in Khorasan Razavi province. Giti and et al. (1390) try to identify and report golden potato cyst nematode occurrence (Globodera rostochiensis) and its distribution in Hamadan province. The aim of this study was to identify plant parasitic nematodes of potato fields in Friedan region in Isfahan province.Materials and Methods: Soil sampling: In order to identify plant parasitic nematodes of potato fields in Friedan region in Isfahan province, 115 soil samples and root samples were collected during spring and summer of 2013 and 2014. Soil samples were taken from the depth of 30 cm put in polyethylene bags with necessary labeled and brought to the laboratory and processed. Processing of samples: Nematodes were extracted from soil samples by sieving and centrifugal flotation technique and from root samples by using blender and centrifuge and  were then transferred to glycerin according to the modified De Grisse method (1969). Genera and species were identified based on morphological and morphometric characters. Species were heat- killed by adding boiling 4% formalin solution and were then transferred to anhydrous glycerin according to De Grisse (1969). The permanent slides were prepared from the extracted nematodes. Measurements and drawing were performed using a drawing tube attached to an "Olympus BH2" light microscope (LM).  .Measurements and drawing: Measurements were taken with an ocular micrometer of "Olympus BH2" model microscope. Drawing were prepared with drawing tube attached to the compound microscope. The nematodes were identified by light microscope based on morphological and morphometric characters.Results and Discussion: In this study, 12 species belonging to 4 genera of the family Tylenchidae, related to infra order Tylenchomorpha were identified as follows: Boleodorus thylactus and B. hyderi , Discotylenchus brevicaudatus, D. attenuatus and D. discretus,  Filenchus afghanicus, F. balcarceanus, F. qurtus, F. vulgaris, F. thornei and F. pratensis and Tylenchus naranensis.In which, four species Bolodorus hyderi, Discotylenchus attenuatus, Filenchus balcarceanus and Tylenchus naranensis are described and two species Boledorus hyderi and Filenchus balcarceanus are reported as new records for fauna nematodes of Iran. Species were identified by valid key (Geraert, 2008). Morphological and morphometric measurements of B. hyderi specimens have been in close agreement to the measurements given by Geraert (2008). This species was compared with the close species Boleodorus volutus. Studied species was similar to the close species tail shape but differ in stylet length and vulva slit situation so that the length of stylet in studied species was more than B. volutus (The length of the style in discussed species is 9-11um and in the similar species is 8-9 um). In addition, vulva slit situation differ in studied these species. V factor is 59 -65 in studied species and 76-79 in the close species. Therefore, population under study was identified as B. hyderi.  This species was collected from soil around roots of potato fields (Abasabad-Chadgan) in Friedan region of Isfahan province as a new record from Iran. In this study, the specimens of F. balcarceanus were collected from soil around roots of potato fields (Geshnizjan-Chadgan) in Friedan region of Isfahan province showed a close resemblance in the morphometric measurements to the original description given by Geraert (2008) with slight variation. This species was compared with close species Filenchus butteus, Filenchus teres and Filenhus retusus. In the species F. butteus, lateral filed marked by four incisures, not areolated delimiting three bands of equal width but in similar species, body has two lateral fields. The length of stylet in studied species was more than F. teres and F. retusus (Stylet length in discussed species is 9 um and in two other species is 7 um).  This species was reported for the first time in Iran.Conclusion: In this study, 12 species from 4 genera of the family of Tylenchidae were identified. Among these genera and species, four species including Bleodorus hyderi, Discotylenchus attenuatus, Filenchus balcarceanus and Tylenchus naranensis are described and two species Bleodorus hyderi and Filenchus balcarceanus are reported as new records for Iran nematode fauna.