In vitro co-cultures of Pinus pinaster with Bursaphelenchus xylophilus: a biotechnological approach to study pine wilt disease

Abstract Main conclusion Co-cultures of Pinus pinaster with Bursaphelenchus xylophilus were established as a biotechnological tool to evaluate the effect of nematotoxics addition in a host/parasite culture system. The pinewood nematode (PWN), Bursaphelenchus xylophilus, the causal agent of pine wilt disease (PWD), was detected for the first time in Europe in 1999 spreading throughout the pine forests in Portugal and recently in Spain. Plant in vitro cultures may be a useful experimental system to investigate the plant/nematode relationships in loco, thus avoiding the difficulties of field assays. In this study, Pinus pinaster in vitro cultures were established and compared to in vivo 1 year-old plantlets by analyzing shoot structure and volatiles production. In vitro co-cultures were established with the PWN and the effect of the phytoparasite on in vitro shoot structure, water content and volatiles production was evaluated. In vitro shoots showed similar structure and volatiles production to in vivo maritime pine plantlets. The first macroscopic symptoms of PWD were observed about 4 weeks after in vitro co-culture establishment. Nematode population in the culture medium increased and PWNs were detected in gaps of the callus tissue and in cavities developed from the degradation of cambial cells. In terms of volatiles main components, plantlets, P. pinaster cultures, and P. pinaster with B. xylophilus co-cultures were all b- and a-pinene rich. Cocultures may be an easy-to-handle biotechnological approach to study this pathology, envisioning the understanding of and finding ways to restrain this highly devastating nematode. Keywords Maritime pine ! Monoxenic culture ! Pinewood nematode ! Relative water content ! Shoots structure ! Volatiles Abbreviations BAP 6-Benzylaminopurine DAI Days after inoculation EPPO European and Mediterranean Plant Protectio

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Correction: Ryss, A.Y.; Subbotin, S.A. New Records of Wood- and Bark-Inhabiting Nematodes from Woody Plants with a Description of <i>Bursaphelenchus zvyagintsevi</i> sp. n. (Aphelenchoididae: Parasitaphelenchinae) from Russia. <i>Plants</i> 2023, <i>12</i>, 382

In the original publication [...

New Records of Wood- and Bark-Inhabiting Nematodes from Woody Plants with a Description of <i>Bursaphelenchus zvyagintsevi</i> sp. n. (Aphelenchoididae: Parasitaphelenchinae) from Russia

Wood- and bark-inhabiting parasitic nematodes are of great economic importance. Nematodes can cause wilt diseases in conifers and deciduous trees. In 2014–2022, during nematology surveys conducted in different regions of Russia and Belarus, adults and dauer juveniles of nematodes were collected from wood, bark and beetle vectors. Using traditional morphological taxonomic characters integrated with molecular criteria, we identified in the studied samples the following nematode species: Aphelenchoides heidelbergi, Bursaphelenchus eremus, B. fraudulentus, B. michalskii, B. mucronatus, B. willibaldi, Deladenus posteroporus, Diplogasteroides nix and Laimaphelenchus hyrcanus, several unidentified species: Aphelenchoides sp.1 and sp.2, Cryptaphelenchus sp.1, sp.2 and sp.3, Laimaphelenchus sp.1, Micoletzkya sp.1, Parasitaphelenchus sp.1, Parasitorhabditis sp.1, three unidentified tylenchid nematodes and a new species, Bursaphelenchus zvyagintsevi sp.n. Morphological descriptions and molecular characterization are provided for B. zvyagintsevi sp. n. belonging to the Abietinus group and B. michalskii belonging to the Eggersi group. Findings of Aphelenchoides heidelbergi, Bursaphelenchus eremus, B. michalskii, Deladenus posteroporus, Diplogasteroides nix and Laimaphelenchus hyrcanus are new records for Russia. Phylogenetic positions of studied species were reconstructed using D2–D3 expansion segments of 28S rRNA gene sequence analysis. The data obtained in this study may help to detect the refugia of opportunistic plant pests and find possible native biocontrol nematode agents of insect vectors causing diseases