Report of <i>Pratylenchus penetrans</i> on quince (<i>Cydonia oblonga</i>) in England

Roots of quince (Cydonia oblonga Mill.) exhibiting lesions/darkening were collected from private property in Sheffield, England (53°23'23.1"N 1°30'53.4"W), along with rhizospheric soil. Nematode extraction revealed the presence of Pratylenchus specimens (60 nematodes per g of root; 100 nematodes/cm3 of soil). No above-ground symptoms were evident. Females were slender with the labial region slightly offset from the body and comprising three annuli (Figure 1A and 1B), measuring 505.6 µm (427.0 – 580.5), a = 22.5 (19.1 – 25.1), b= 6.85 (5.3 – 10.0), c= 17.3 (9.4 – 27.0), and V% = 81.6 (78.9 – 83.0) (n = 10). Basal knobs were rounded but frequently found as slightly indented/cupped in some individuals (1B and 1C). The tail was rounded and smooth (Figure 1E). Males were common and slightly smaller than females (Figure 1D), measuring 482 µm (477.81 – 489.22), a = 25.9 (24.6 – 27.3), b= 7.3 (6.2 – 9.5), c= 15.2 (14.0 – 15.0) (n = 4). These characteristics are consistent with Pratylenchus penetrans (Loof, 1991; Castillo and Vovlas, 2007). To validate morphological observations, molecular identification was carried out using 28S rDNA D2A/D3B primers (Gamboa-Cortés et al., 2023). DNA was extracted from hand-picked individuals according to Sonawala et al. (2024). PCR was carried out using 5 µL of the digested sample with KOD Xtreme polymerase (Sigma Aldrich) using an initial denaturation at 94˚C for 2 min; 40 cycles of 98˚C for 10 s, 55˚C for 30 s and 68˚C for 1 min). Purified PCR products (Monarch Gel Extraction Kit) were sequenced, compared to those publicly available for Pratylenchus spp. and Xiphinema index, and aligned and trimmed using Clustal Omega (Madeira et al., 2024) on Geneious (2025.0.3) using default settings. Model selection (TPM3+G4) and phylogenetic tree inference (SH-aLRT, 1000 bootstraps (Minh et al., 2020)) were performed on the aligned sequences using IQ-TREE 2 version 2.2.0 (Figure 2A). Phylogenetic analysis corroborated the morphological identification of P. penetrans (Figure 2A). Nematodes were multiplied and maintained on maize (Zea mays L.) ‘B73’ and tomato (Solanum lycopersicum L.) ‘Moneymaker’ in growth chambers (light/dark cycle of 16h/8h at 30°C/21°C, respectively). To assess the host status of quince, five plants of C. oblonga (acquired commercially), and an equal number of Maize ‘B73’, were inoculated with 1,200 individuals. The inoculum was administered into two holes (2 cm depth) close to the stem and partially filled with vermiculite to avoid heat stress. Plants were assessed 90 days post-inoculation, as previously reported for sufficient reproduction of Pratylenchus brachyurus on Eucalyptus spp. (Souza and Inomoto, 2021). For quince and maize, similar reproductive values (2.3 and 2.2) and nematodes per gram of root (410 and 426) were found, respectively. Quince-infested roots were lesioned and decaying (Figure 2B), and reduced in weight by 31% compared to non-inoculated controls (7.8 g and 11.3 g, respectively, p&lt;0.05, Student’s t-test). Taken together, these data demonstrate that P. penetrans successfully reproduces on quince, and induces significant damage to host roots, indicating both host status and potential economic impact. The presence of P. penetrans should be considered when establishing quince orchards, as trees can become a source of inoculum over-season and/or to fast-growing crops (e.g., wheat or maize) grown near them. To our knowledge, this is the first report of P. penetrans on quince in England.