Six First Reports of Pin Nematodes from Portugal, with an Update of the Systematics, Genetic Diversity, and Phylogeny of the Genus <i>Paratylenchus</i> (Nematoda: Tylenchulidae)

Abstract

Pin nematodes (Paratylenchus spp.) currently comprise 132 species of polyphagous plant ectoparasites with at least seven species that are plant pathogenic emphasizing the need for correct identification to establish an appropriate management strategy. Sequences of highly conserved regions of ribosomal and mitochondrial RNA genes are a powerful species-level diagnostic tool within Tylenchulidae. A nematological survey was conducted from 2019 to 2021 in commercial vineyards distributed in four major wine-producing regions in the Central and South Portugal. Nine populations of Paratylenchus spp. were isolated from the rhizosphere of grapevines that were characterized from morphological data and molecular phylogenetic analysis using two rRNA genes (D2–D3 expansion segments of the 28S, and partial 18S) and a region partial of the COI mtRNA gene. Contrasting morphological hypotheses with molecular data provided rapid detection of six species, specifically P. goodeyi, P. hamatus, P. pedrami, P. tenicaudatus, P. variabilis, and P. veruculatus. Bayesian inference (BI) phylogenetic trees for these molecular markers established phylogenetic relationships underscore the importance of using genomic and molecular phylogenetic data for accurate pin nematode identification at the species level. To our knowledge, this is the first report of Paratylenchus spp. in Portugal, extending the geographical distribution of these species in the Mediterranean Basin, and the first record of P. goodeyi, P. pedrami, P.variabilis, P. veruculatus and P. tenicaudatus parasitizing grapevine.

Keywords

• Bayesian inference
• D2–D3 expansion segments of large ribosomal subunit 28S
• cytochrome c oxidase subunit 1
• mitochondrial RNA
• partial small ribosomal subunit
• morphology