Integrative diagnosis and parasitic habits of Cryphodera brinkmani a non-cyst forming heteroderid nematode intercepted on Japanese white pine bonsai trees imported into Italy

Abstract

The non-cyst forming heteroderid nematode Cryphodera brinkmani was detected in Italy parasitizing roots of Japanese white pine bonsai (Pinus parviflora) trees imported from Japan. Morphology and morphometrical traits of the intercepted population on this new host for C. brinkmani were in agreement with the original description, except for some minor differences on male morphology. Integrative molecular data for this species were obtained using D2-D3 expansion regions of 28S rDNA, ITS1-rDNA, the partial 18S rDNA, and the protein-coding mitochondrial gene, cytochrome oxidase c subunit I (COI). The phylogenetic relationships of this species with other representatives of non-cyst and cyst-forming Heteroderidae using ITS1 are presented and indicated that C. brinkmani clustered together with other Cryphodera spp. and with Meloidodera alni suggesting a monophyletic origin of non-cyst forming nematodes (Heteroderinae sensu Luc et al. 1988), which have been considered close to the ancestor of most species of Heteroderidae. Histological observations of P. parviflora feeder roots infected by C. brinkmani indicated that nematode females induce similar anatomical alterations to those reported for C. kalesari and consisting of formation of a single uninucleate giant cell (nurse cell) with hypertrophied nucleus, prominenet nucleolus, thickened cell wall and expanding into the stele and in contact of xylem, vacuum cambium and phloem. These findings are in agreement with the results of the phylogenetic analysis and indicate a close relationship in the plant responses induced by Cryphodera nematode females with those caused by the genetically related Meloidodera spp., which also induce formation of a uninucletate giant cell.

Anatomical Alterations in Plant Tissues Induced by Plant-Parasitic Nematodes

“…Cryphodera brinkmani (I–L) : (I) Root segment of pine with the posterior portion of the body of a white female (n) protruding from the root surface. (J–L) Cross sections of pine roots showing nematode female body (n) embedded in the cortical parenchyma and an uninucleate giant cell (ugc) with hypertrophied nucleus (hn) (Vovlas et al, 2013 ; with permission of Springer). (M) Cross section of corn root infected by Meloidodera charis showing the single nurse cell (nc) (Source: N. Vovlas).…”

Molecular characterisation and phylogenetic relationships of cystoid nematodes of the family Heteroderidae (Nematoda: Tylenchida)

“…The newly obtained sequences for each gene (D2-D3 of 28S rRNA, ITS rRNA and the COI mtDNA) were aligned using ClustalX 1.83 (Thompson et al, 1997) with their corresponding published gene sequences (Subbotin et al, 2001(Subbotin et al, , 2006Ferris et al, 2004;Nguyen et al, 2011;Long et al, 2013;Vovlas et al, 2013;Zhuo et al, 2014a, b;Van den Berg et al, 2016, and others). Alignment program was run with default (gap opening 15.0; gap extension 6.66) parameters for the D2-D3 and COI datasets and modified (gap opening 5.0; gap extension 3.33) parameters for the ITS dataset.…”

“…Phylogenies of cystoid nematodes were reconstructed by several authors using analysis of morphological characters (Krall & Krall, 1978;Coomans, 1979;Ferris, 1979;Wouts, 1985;Baldwin & Schouest, 1990). In recent years new insights into the phylogeny of this group and its relationships with other Heteroderidae have also been proposed using the analysis of rRNA gene sequences (Subbotin et al, 2001(Subbotin et al, , 2006Ferris et al, 2004;Nguyen et al, 2011;Vovlas et al, 2013;Zhuo et al, 2014a).…”

Cryphodera gayae n. sp. (Nematoda: Heteroderidae), from root of Lagerstroemia indica in Korea

“…The new species having morphological characters of protruding vulval lips, flat to concave anus-vulva profile, three lateral lines in J2s, appears most similar to C. brinkmani but differs by the shorter stylet length of J2 (26.8-31.3 µm vs 31.6-35.4 µm), stylet knob shape of J2 (flat posteriorly vs concave), egg numbers in mature female (64-69 vs 15-45). Also, J2 of C. brinkmani exhibited a small mucro at the tip of the tail(Vovlas et al, 2013) but C. gayae n. sp. has sharply pointing tip with constriction at the middle of hyaline without mucro-like tip.…”