Populations of Paratrichodorus were collected from the root zones of citrus plants (Citrus sp.) cultivated at the Indian Agricultural Research Institute (IARI) farm in New Delhi. The study aimed to characterize these populations both morphologically and molecularly for accurate species identification. Morphology and morphometrics (21 females and 20 males) were studied and compared with the species described under the genus. The Paratrichodorus female population body lengths of 500.0-690.4 μm, with a = 16.5-22.6 and b = 4.5-6.2. Vulval position averaged at 47% of body length, while the Onchiostyle measured 28-39 μm. In contrast, Paratrichodorus males measured 498.2-645.2 μm, with a = 16.0-22.1 and b = 3.9-6.0. Their spicule length ranged from 30.1 to 36.9 μm, with an average of 32.9 μm. We considered the Paratrichodorus population is quite different from the known and described species. At the molecular level, amplified sequence fragments encompassing the 18S region for the Paratrichodorus isolate iari123. Subsequent phylogenetic analysis of the obtained 18S rRNA sequence (MZ567177) suggests a potential correlation with Paratrichodorus teres (Hooper, 1962) Siddiqi, 1974. This particular sequence has been formally submitted and documented in GenBank under the accession number MZ567177.

18S rRNA, Paratrichodorus, morphometrics

A population of Paratrichodorus recovered from the rhizosphere of citrus plants was attempted to characterize based on morphology, morphometrics, and molecular studies. Morphology and morphometrics (21 females and 20 males) were studied and compared with the species described under the genus. We considered the Paratrichodorus population is quite different from the known and described species. Further, we attempted to generate the molecular information for further characterization. The amplified sequence fragments of 18S for Paratrichodorus isolate iari123 were ca 800 bp. The sequence was submitted to GenBank under the accession number MZ567177 (18s rRNA). A BLAST search against the NCBI database showed that the 18s rRNA sequence of Paratrichodorus isolate iari123 was 98.08% identical with Paratrichodorus teres (KJ636338.1; query coverage = 99%, e-value = 0). However, 18s rRNA phylogenetic analysis has not resolved the identity of the species. Therefore, the population needs additional sequence information from the ITS-I & ITS-II of 18S, D2-D3 of 28S regions, and COI of mt DNA for confirmation of the species.

Basant Deshwal (2023). Morphological and molecular characterisation of stubby root nematode (Paratrichodorus Siddiqi, 1974) parasitizing citrus (Citrus sp.) from IARI, New Delhi, India. Biological Forum – An International Journal, 15(8): 482-487.