LAUSR

Heracleum hemsleyanum, a perennial flowering herb belonging to the Apioideae family, is primarily distributed in Southwestern China, including Hubei and Sichuan Provinces (She et al., 2005). Its roots have been traditionally used to treat rheumatism, limb cramps, and vitiligo (Fang et al., 2004). In September 2024, approximately 35% of H. hemsleyanum plants in the plant base of Enshi, Hubei Province (30°32′25.67″N, 109°48′48.46″E), exhibited stunted growth, reduced leaf size, and conspicuous root galls, suggesting severe root-knot nematode infection. Affected roots were collected, dissected, and nematodes were extracted for morphological and molecular identification. The morphological diagnosis of the nematode species was measured as follows. Measurements of adult females (n = 20): body length (L) = 828.15 ± 73.69 μm, body width (BW) = 556.77 ± 36.72 μm, stylet length (ST) = 15.58 ±0.93 μm, dorsal pharyngeal gland orifice to stylet base (DGO) = 4.46 ± 0.38 μm, vulval slit length = 17.98 ± 2.03 μm, and vulval slit to anus distance = 13.25 ± 1.48 μm. Males (n = 10): L = 1,302.68 ± 96.48 μm, BW = 28.56 ± 2.57 μm, ST = 19.86 ± 0.97 μm, DGO = 4.92 ± 0.56 μm, and spicule length = 29.02 ± 1.72 μm. Second-stage juveniles (J2s) (n=20): L = 368.59 ± 17.26 μm, BW = 16.02 ± 1.38 μm, ST = 13.56 ± 0.98 μm, DGO = 2.69 ± 0.54 μm, tail length = 41.85 ± 4.76 μm, hyaline tail terminus = 12.02 ± 2.04 μm. Eggs (n=20): L = 78.68 ± 3.64 μm, and width = 38.94 ± 3.02 μm. All the morphological characteristics of the identified species were consistent with the descriptions of Meloidogyne hapla Chitwood, 1949 (Whitehead, 1968). Species identification was further confirmed by PCR with 28S rDNA D2/D3 region primers MF/MR (5′-GGGGATGTTTGAGGCAGATTTG-3′, 5′-AACCGCTTCGGACTTCCACCAG-3′) (Hu et al., 2011) and the variable V3 and V5 regions of the 18S rDNA primers 18sf1/18sr1 (5´-CGCAAATTACCCACTCTC-3´/5´AGTCAAATTAAGCCGCAG-3´) (Waite et al., 2003). The 478 bp and 750 bp sequences (GenBank accession no. PX022967 and PV931984, respectively) were 99.57% and 100% identical to the PV911583 and PV911573 sequences, respectively. To confirm the pathogenicity of the nematode population, fifteen healthy three-month H. hemsleyanum seedlings cultured in sterilized sand were each inoculated with 2,000 J2s from the egg masses of nematode population. Fifteen non-inoculated seedlings served as negative controls. After three months in a growth chamber maintained at 22°C, galls and egg masses appeared on the roots of inoculated plants consistent with the symptoms observed in the field, whereas the controls showed no symptoms. Females collected from inoculated plants were identified as M. hapla with the species-specific primer MH-F/MH-R (5´-GAATAGTCTCAACGTTTATC-3´/5´-ATGTGACAGCGAAAAGAATT-3´) (Feng et al., 2008), which amplified a fragment of 447 bp (PV931994). To our knowledge, this is the first report of M. hapla infecting H. hemsleyanum. Given its medicinal importance, this finding is critical for developing effective management strategies to prevent further spread.