نخستين گزارش گونه‌ي Meloidogyne javanica (Treub, 1885) Chitwood, 1949 از نارنگي در ايران

First report of Meloidogyne javanica (Treub, 1885) Chitwood, 1949 from tangerine tree in Iran

نماتد‌ ريشه‌گرهي انگل اجباري گياهان است كه تعداد زيادي از گياهان آوندي را در سراسر جهان مورد حمله قرار مي‌دهد و از نظر اقتصادي بسيار مهم مي‌باشد. در طي بررسي تنوع زيستي نماتدهاي انگل گياهي در باغ‌هاي مركبات استان خوزستان درسال 97-1396، يك جمعيت نماتد ريشه‌گرهي از نمونه ‌خاك وريشه نارنگي جمع‌آوري شد. ماده‌هاي بالغ و لارو سن دو از ريشه‌هاي آلوده استخراج گرديد. بعد ازكشتن و ثابت كردن نماتد‌ها،اسلايد دائم تهيه شد. شناسايي گونه با استفاده از كليد‌هاي معتبر صورت گرفت. DNA ژنومي از لارو سن دو و ماده‌هاي بالغ استخراج گرديد. DNA استخراج شده توسط جفت آغازگر ناحيه D2/D3 از ژن 28S و جفت آغازگرهاي ناحيه 18S تكثير و توالي‌يابي شد. بر اساس خصوصيات ريخت‌شناختي، ريخت‌سنجي و تجزيه و تحليل فيلوژني نواحي تكثير شده، گونه M. javanica شناسايي گرديد. تفاوت‌هاي ريخت‌شناختي جمعيت به‌دست‌آمده با ساير جمعيت‌هاي اين گونه مورد بحث قرار گرفت. در اين مطالعه دو قطعه 799 جفت بازي توسط آغازگرهاي ناحيه 28S و دو قطعه 1678 جفت بازي توسط آغازگرهاي ناحيه 18S توليد شد. بر اساس منابع موجود، اين اولين گزارش از آلودگي نارنگي به نماتد ريشه گرهي M. javanica در ايران مي‌باشد.

Background and Objectives: The root-knot nematode is an obligatory plant parasite that attacks a large number of vascular plants worldwide and is economically important. The present study aimed to identify the Meloidogyne javanica species based on morphological, morphometric data and molecular characterization. Materials and Methods: During a survey on the biodiversity of plant-parasitic nematodes in citrus orchards of Khuzestan province from 2017 to 2018, a root-knot nematode population was collected from soil and root samples of tangerine. Adults and the second-stage juveniles were extracted from the infected roots. After killing and fixing the nematodes, permanent slides were prepared. Species identification was performed using valid keys. Genomic DNA was extracted from both juvenile and adult females. The extracted DNA was amplified and sequenced by the primers of the D2-D3 expansion segments of the 28S rRNA gene and the 18S rRNA gene. The newly obtained sequences of the D2-D3 fragments of 28S and 18S rRNA gene sequences and additional sequences of relevant species were selected after a BlastN search and were aligned by Clustal X using the default parameters. The both phylogenetic analyses were evaluated under the GTR + G + I model with two million generations. Results: M. javanica was identified based on morphological, morphometric data and phylogenetic analysis of amplified regions. The morphological differences of the recovered population in comparison with other populations were discussed. In this study, two 799 bp fragments were generated by the 28S rDNA gene region primers and two 1678 bp fragments were generated by the 18S rDNA gene region primers. Discussion and conclusion: The perineal pattern of the studied female nematode is distinguished from the other species of this genus by having two parallel lines at the lateral surfaces of the body so that these lines clearly divide the perineal pattern into the dorsal and ventral parts. To the best of our knowledge, this is the first report of M. javanica in association with tangerine in Iran.