مطالعه ریخت شناسی و مولکولی یک جمعیت از نماتد نیزه ای (Hoplolaimus sp) از باغات خرما در استان کرمان

Date palm (Phoenix dactylifera L.), is an important economic and strategic agricultural product in the southern regions of Kerman province. The recent decline and drought of date palm trees in the south of the country, and the high cultivated areas in the south of Kerman province, show the need to monitor the region's orchards. To determine the possible role of plant-parasitic nematodes as one of the factors threatening the health of this crop, several soil samples were collected from the roots and the rhizosphere of date palm trees in some parts of southern Kerman province since 2020 to 2021, and transferred to the Plant Pathology Laboratory of Vali-e-Asr University of Rafsanjan. Nematodes were extracted using sieving and centrifugation. After fixing and transferring the nematodes to glycerin, permanent microscopic slides were prepared. A population of lance nematode was recovered during this study and was identified at species level using the available identification keys and original descriptions of th e species. It was identified as H. indicus. All the morphological characteristics of this population were in accordance with those of the type population. The species differs from the three closely related species H. columbus, H. chambus and H. seinhorsti by having five nuclei in pharyngeal glands and having male and active spermatheca. It differs from H. dubius in number of lines in lateral field and number of pharyngeal glands nuclei. The two 18S and 28S rDNA fragments of the recovered population were sequenced and deposited into the GenBank database. Bayesian phylogenetic trees were reconstructed for both loci. In the 28S rDNA tree, the newly recovered population fell into a maximally supported clade (BPP= 1.00) including sequences from other populations of the species and sequences assigned to three H. seinhorsti, H. columbus and H. dubius. Its phylogenetic relationships were however not resolved due to polytomy. This clade had a highly supported sister relation with the clade including H. pararobustus and another population of Hoplolaimus. In 18S rDNA phylogeny, three sequences of the species, along with populations of the other three species, formed a clade (BPP= 1.00). The 18S rDNA sequence of the recovered population formed a highly supported sister clade with two populations of H. columbus and the relationship between the two species was resolved in this tree. The 18S sequence of H. indicus was made available for the first time.