Coriander (Coriandrum sativum), which can be used for its root, stem, and leaf as both food and medicine (Prachayasittikul et al. 2018), is widely cultivated in China. The coriander cultivation area of Guanzhong region, including Xi' an, Xianyang, and Weinan, is 20 million m2, which accounts for 85.7% of the total cultivation area in Shaanxi. In September 2022, obvious galls were observed on the roots of coriander plants (cv. Xiaoye) growing in a field in Huyi District, Xi' an City (34°1'26.4"N, 108°31'58.8"E). The diseased plants did not show obvious above-ground symptoms. To identify the species, second-stage juveniles (J2s) and males were collected from soil in the root zone, and adult females were isolated from galls of diseased roots. The perineal patterns of adult females (n = 20) were round to oval, with high dorsal arches and no obvious lateral lines were observed. Morphological measurements of females (n = 20) included body length (L) = 682 ± 56 (554 to 780) μm, body width (BW) = 522 ± 45 (420 to 597) μm, stylet = 14.9 ± 0.9 (13.4 to 16.3) μm, dorsal pharyngeal gland orifice to stylet base (DGO) = 5.3 ± 0.5 (4.3 to 6.3) μm, vulval slit length = 26 ± 2.8 (20 to 32) μm, vulval slit to anus distance = 21 ± 1.7 (18.5 to 26) μm. Measurements of males (n = 8) were L = 1398 ± 57 (1308 to 1450) μm, BW = 28 ± 2.9 (23 to 32) μm, stylet = 16.1 ± 0.8 (15.3 to 17.3) μm, DGO = 4.5 ± 0.5 (3.5 to 4.9) μm, spicules = 27 ± 1.1 (26 to 29) μm. Measurements of J2s (n = 20) were as follows: L = 434 ± 16.8 (391 to 477) μm, BW = 15.6 ± 0.9 (13.7 to 17.3) μm, stylet = 12.6 ± 0.6 (11.3 to 13.6) μm, DGO = 3.9 ± 0.3 (3.4 to 4.5) μm, tail = 52 ± 4.0 (47 to 60) μm, hyaline tail length = 15.6 ± 1.3 (13.6 to 18.6) μm. These morphological characteristics were consistent with those described for Meloidogyne enterolobii (Yang and Eisenback 1983). Ten females were put in 10 tubes for DNA extraction following Htay et al. (2016). The ITS-rDNA sequence was amplified using the primers 18S/26S (Vrain et al. 1992). A 765 bp fragment was obtained and the sequence (GenBank OR789453) was 99.87% identical to sequences of M. enterolobii (MT406251 and MT067559). The mtDNA CoxII-16S sequence was amplified using primers C2F3/1108 (Powers and Harris, 1993). The sequence was 705 bp (OR795028) and 100% identical to sequences of M. enterolobii (MK455870 and MZ643270). A single 236 bp fragment was amplified using species-specific primers Me-F/Me-R, confirming the species as M. enterolobii (Long et al. 2006). The infection test was conducted in a greenhouse at 27 ± 2℃. Eight 2-week-old coriander plants (cv. Xiaoye) were individually grown in pots filled with sterilizer soil and inoculated with 800 J2s hatched from collected M. enterolobii egg masses. Forty-five days after nematode inoculation, the inoculated plants had galled roots like those observed in the field. The reproduction factor (final population density/initial population density) was 11.9 ± 2.0, indicating coriander was a suitable host for M. enterolobii. No symptoms were observed in controls. To our knowledge, this is the first known natural infection of coriander with M. enterolobii in China. M. enterolobii has been reported on various crops in southern provinces of China (EPPO, 2023). Considering the high level of agricultural trade between different regions, there is a high risk of M. enterolobii transmission to Guanzhong region through infested soil and susceptible plant materials. Further monitoring and research on effective control strategies are needed to prevent the spread of this nematode.
Keywords: Meloidogyne enterolobii; Shaanxi; coriander.