First report of potato rot nematode, Ditylenchus destructor Thorne, 1945 infecting Codonopsis pilosula in Gansu province, China

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Journal of Nematology

Society of Nematologists

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First report of potato rot nematode, Ditylenchus destructor Thorne, 1945 infecting Codonopsis pilosula in Gansu province, China

Chunhui Ni / Shuling Zhang / Huixia Li * / Yonggang Liu / Wenhao Li * / Xuefen Xu / Zhipeng Xu

Keywords : Chinese herbal medicine, Ditylenchus destructor, Molecular biology, Morphology, New host

Citation Information : Journal of Nematology. Volume 52, Pages 1-2, DOI: https://doi.org/10.21307/jofnem-2020-087

License : (CC-BY-4.0)

Received Date : 10-May-2020 / Published Online: 31-August-2020

ARTICLE

ABSTRACT

In November 2019, stem nematode was found on Codonopsis pilosula in Tanchang county, Gansu province, China. The population of stem nematode was identified on the basis of both molecular and morphological methods. The morphological and morphometric characteristics of this nematode population matched with Ditylenchus destructor Thorne, 1945. The sequences of rDNA-ITS and D2/D3 region of 28S-rRNA similarity with the D. destructor. The pathogenicity results revealed the symptom of dry rot on C. pilosula was caused by this nematode. To our knowledge, this is the first report that D. destructor on C. pilosula in China.

Codonopsis pilosula (Franch.) Nannf. (Campanulales: Campanulaceae) is a perennial herbaceous plant and its rhizomes are widely used in medicinal purpose. The acreage of C. pilosula is 2667 to 3333 hm2 annually planted in Gansu province, and the total output is 4000-5000 tons (Hou et al., 2019). During a survey for nematodes on C. pilosula in 2019 in Gansu province, China, diseased roots with wrinkled cuticles and tan or dark brown spots were observed in the fields in Tanchang county (N 34°23′82″, E 104°36′27″).

The roots of diseased plants were collected and nematodes were extracted using a modified Baermann technique (Hooper, 1990). The results of morphological and morphometric characteristics of this nematode population were as following. The lip regions of females were plain with obscure constriction and stylets were 9.9 to 10.8 (μm) long with distinct knobs. Oval median bulbs were with valves, narrow isthmus and the posterior esophageal extended over intestines dorsally. Tail tips were rounded. The vulva of females at the back of the body were slightly protruding and the posterior uterine sac extended to the anus, which was about 3/4 of the distance from the vulva to the anus.

The morphometrics (mean ± SD, n = 20) of females were as following: L = 980.8 ± 182.5 (779.1-1,131.2) μm, a = 39.7 ± 6.5 (33.6-49.2), b = 6.7 ± 1.0 (5.3-7.6), c = 15.6 ± 2.0 (13.3-18.5), c′ = 3.8 ± 0.3 (3.4-4.2), V = 81.3 ± 2.4 (77.8-83.9), V′ = 106.9 ± 0.9 (105.7-108.1), stylet length: 11.3 ± 0.9 (9.8-12.3) μm, tail length: 62.8 ± 9.2 (55.6-78.5) μm, ABW = 16.5 ± 2.5 (13.4-20.1) μm, PUS = 65.5 ± 5.8 (61.7-78.3) μm.

Male bodies were similar to those of females and slightly bent spicules were strong with bursas encircleing to 1/3 of the tail. The morphometrics (mean ± SD, n = 20) of males were as following: L = 772.0 ± 92.8 (679.8-876.6) μm, a = 40.3 ± 2.8 (37.3-43.0), b = 5.4 ± 0.4 (4.9-6.0), c = 12.8 ± 1.1 (11.5-14.5), c′ = 4.1 ± 0.3 (3.7-4.5), stylet length: 10.3 ± 0.4 (9.9-10.8) μm, tail length: 60.2 ± 5.0 (55.5-67.7) μm, ABW = 16.5 ± 2.5 (13.4-20.1) μm. These morphological characteristics matched with Ditylenchus destructor by Thorne. (Thorne, 1945).

DNA of single nematode (n = 5) was isolated using the Proteinase K method (Kumari and Subbotin, 2012) and amplification of rDNA-ITS region and D2/D3 fragments of the 28S rDNA sequencing were performed with the universal primers 18S (5′-TTGATTACGTCCCTGCCCTTT-3′) and 26S (5′-TTTCACTCGCCGTTACTAAGG-3′) (Vrain et al., 1992). D2A (5′-ACAAGTACCGTGAGGGAAAGTTG-3′) and D3B (5′-TCGGAAGGAACCAGCTACTA-3′) (Subbotin et al., 2006). The sequences of rDNA-ITS (978 bp; MT150860, MT150861) and D2/D3 region of 28S (735bp; MT672685, MT672686) were submitted to GenBank, and the BLAST result showed that rDNA-ITS sequences were 99.90%-100% identical to the D. destructor on potato from China (FJ911551) and Russia (AY987007), D2/D3 region of 28S sequences were 100% identical to the D. destructor on potato from Iran (HQ235698) and on maize from China (MT585824). Therefore, the nematode population was identified as D. destructor.

To confirm the pathogenicity of the population, the healthy C. pilosula seedlings (sterilized with 75% alcohol and 2.5% NaClO) were planted into sterilized substrates in a greenhouse at 25 to 30°C. After two weeks, every plant was inoculated with about 5000 mixed-stage nematodes near roots, repeated 5 plants and three plants served as control. After 60 days, symptoms on C. pilosula similar to those in the field were observed and D. destructor was isolated from inoculated plants, with population densities ranging from 52 to 101 mixed-stage nematode per 1g of fresh roots. The control plants remained healthy. To our knowledge, this is the first report that D. destructor on C. pilosula. By now, D. destructor damaged on angelica and potato in Gansu province (Wang et al., 1990; Li et al., 2016). Since C. pilosula is an important cash crop in Gansu province (Bi et al., 2008), more attentions should be paid to D. destructor on C. pilosula.AcknowledgmentsThis research was supported by the National Natural Science Foundation of China (31760507) and National Key Research and Development Plan (2018YFC1706301).

Acknowledgements

This research was supported by the National Natural Science Foundation of China (31760507) and National Key Research and Development Plan (2018YFC1706301).

References


  1. Bi, H. Y. , Zhang, L. P. , Chen, Z. and Wu, B. 2008. An overview of research on germplasm resources of Radix Codonopsis and their utilization. China Journal of Chinese Materia Medica 33:103–107 (in Chinese).
  2. Hooper, D. J. 1990. “Extraction and processing of plant and soil nematodes”, In Luc, M. , Sikora, R. A. and Bridge, J. (Eds), Plant Parasitic Nematodes in Subtropical and Tropical Agriculture. Wallingford: CAB International, pp. 45–68.
  3. Hou, J. , Guo, H. R. and Zhao, L. 2019. The development and prospect of Codonopsis Radix food value. Journal of Traditional Chinese Veterinary Medicine 38:20–23 (in Chinese).
  4. Kumari, S. and Subbotin, S. A. 2012. Molecular characterization and diagnostics of stubby root and virus vector nematodes of the family Trichodoridae (Nematoda: Triplonchida) using ribosomal RNA genes. Plant Pathology 61:1021–1031.
  5. Li, H. X. , Xu, P. G. , Li, J. R. , Jian, J. Z. , Zhao, P. and Peng, D. L. 2016. Identification of the pathogenic nematodes from potatoes in Dingxi of Gansu Province. Journal of Plant Protection 43:580–587 (in Chinese).
  6. Subbotin, S. A. , Sturhan, D. , Chizhov, V. N. , Vovlas, N. and Baldwin, J. G. 2006. Phylogenetic analysis of Tylenchida Thorne, 1949 as inferred from D2 and D3 expansion fragments of the 28S rRNA gene sequences. Nematology 8:455–474.
  7. Thorne, G. 1945. Ditylenchus destructor n. sp. the potato-rot nematode, and Ditylenchus dipsaci (Kuhn, 1857) Filipjev, 1936, the teasel nematode (Nematode: Tylenchidae). Proceedings of Helminthology of Society of Washington 12:27–33.
  8. Vrain, T. C. , Wakarchuk, D. , Lévesque, A. C. and Hamilton, R. I. 1992. Intraspecific rDNA restriction fragment length polymorphisms in the Xiphinema americanum group. Fundamental and Applied Nematology 15:563–573.
  9. Wang, Y. J. , Liu, F. Z. H. , Sheng, X. L. , Sun, Z. , Huo, K. C. , Jin, X. L. and Miao, X. C. 1990. On the causal nematode of angellca “Makou Bing” disease and its control. Acta Phytopathologica Sinica 20:13–19 (in Chinese).
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REFERENCES

  1. Bi, H. Y. , Zhang, L. P. , Chen, Z. and Wu, B. 2008. An overview of research on germplasm resources of Radix Codonopsis and their utilization. China Journal of Chinese Materia Medica 33:103–107 (in Chinese).
  2. Hooper, D. J. 1990. “Extraction and processing of plant and soil nematodes”, In Luc, M. , Sikora, R. A. and Bridge, J. (Eds), Plant Parasitic Nematodes in Subtropical and Tropical Agriculture. Wallingford: CAB International, pp. 45–68.
  3. Hou, J. , Guo, H. R. and Zhao, L. 2019. The development and prospect of Codonopsis Radix food value. Journal of Traditional Chinese Veterinary Medicine 38:20–23 (in Chinese).
  4. Kumari, S. and Subbotin, S. A. 2012. Molecular characterization and diagnostics of stubby root and virus vector nematodes of the family Trichodoridae (Nematoda: Triplonchida) using ribosomal RNA genes. Plant Pathology 61:1021–1031.
  5. Li, H. X. , Xu, P. G. , Li, J. R. , Jian, J. Z. , Zhao, P. and Peng, D. L. 2016. Identification of the pathogenic nematodes from potatoes in Dingxi of Gansu Province. Journal of Plant Protection 43:580–587 (in Chinese).
  6. Subbotin, S. A. , Sturhan, D. , Chizhov, V. N. , Vovlas, N. and Baldwin, J. G. 2006. Phylogenetic analysis of Tylenchida Thorne, 1949 as inferred from D2 and D3 expansion fragments of the 28S rRNA gene sequences. Nematology 8:455–474.
  7. Thorne, G. 1945. Ditylenchus destructor n. sp. the potato-rot nematode, and Ditylenchus dipsaci (Kuhn, 1857) Filipjev, 1936, the teasel nematode (Nematode: Tylenchidae). Proceedings of Helminthology of Society of Washington 12:27–33.
  8. Vrain, T. C. , Wakarchuk, D. , Lévesque, A. C. and Hamilton, R. I. 1992. Intraspecific rDNA restriction fragment length polymorphisms in the Xiphinema americanum group. Fundamental and Applied Nematology 15:563–573.
  9. Wang, Y. J. , Liu, F. Z. H. , Sheng, X. L. , Sun, Z. , Huo, K. C. , Jin, X. L. and Miao, X. C. 1990. On the causal nematode of angellca “Makou Bing” disease and its control. Acta Phytopathologica Sinica 20:13–19 (in Chinese).

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