Morphological and molecular identification of cyst nematode species (Heterodera spp.) in Algerian cereal fields

Abstract

Cereal cyst nematodes (Heterodera spp.) are distributed globally and cause severe production losses of small grain cereals. To investigate the occurrence of cereal cyst nematodes in wheat-growing areas of Algeria, a survey was conducted and 27 cereal cyst nematode populations were collected. The populations were initially identified based on their morphological and morphometric characters, followed by molecular methods using speciesspecific primers, complemented by ITS-rDNA sequences. The morphological and morphometric features of second-stage juveniles (J2s) and cysts supported the presence of three Heterodera species: H. avenae, H. filipjevi and H. hordecalis. All morphological values of these distinct populations were very similar to those previously described for these species. Using species-specific primers for H. avenae and H. filipjevi, the specific bands of 109 bp and 646 bp confirmed the morphological identification of both species, respectively. In addition, the internal transcribed spacer (ITS) regions were sequenced to study the diversity of the 27 populations. These sequences were compared with those of Heterodera species available in the GenBank database (www.ncbi.nlm.nih.gov) and re-confirmed the identity of the species. Nineteen sequences of ITS-rDNA were similar (99–100%) to the sequences of H. avenae published in the GenBank, six sequences were similar (99–100%) to H. hordecalis, and two were similar (98–99%) to H. filipjevi. The results of this study are of great value to breeding programs and extension services, where they will contribute to the design of control measures to keep damaging nematodes in check.

Keywords

• cereals
• heterodera spp.
• cyst nematode
• its-rdna
• wheat