Determining the identity of Pratylenchus species in the WA Wheatbelt

Rhys G. R. Copeland1, Professor Michael G. K. Jones1, Dr John Fosu-Nyarko1, Dr Sarah Collins2

1Crop Biotechnology Research Group, Murdoch University, Perth, Australia
2Department of Primary Industries and Regional Development, Perth, Australia.

Abstract:

Root-lesion nematodes (RLNs) (Pratylenchus spp.) are endoparasitic plant pests that are amongst the top three most economically important plant-parasitic nematodes. They have wide host ranges, including major crops such as wheat and barley, and cause estimated annual yield losses of 15 and 50% in Western Australia (WA).  For effective pest management in crops it is important to identify the species present.  Pratylenchus curvicauda was recently found in soils of grain-growing areas of WA by Begum et al. (2019). These soils had been identified previously as containing Pratylenchus quasitereoides, but Begum et al. (2019) found that P. curvicauda was the predominant species.  In this project the aim was to re-assess the prevalence of P. quasitereoides and/or P. curvicauda in the WA wheatbelt.  Genomic DNA was extracted from 50 RLNs isolated from soil samples from a cereal crop near Darkan, WA.  A segment of the D2-D3 region of the 28s rDNA sequence was amplified, cloned and the sequences used for analyses.  Phylogenetic relationships of the sequences were constructed with those of 52 recognised and 18 unspecified species of Pratylenchus from 17 regions worldwide.  We identified RLNs closely related to three Pratylenchus species: P. curvicauda (85.2%), P. penetrans (11.1%) and P. quasitereoides (3.7%).  Only one sequence with a close relationship to P. quasitereoides (Hodda et al., 2014) was found. These results support the findings of Begum et al. (2019) and suggest that P. curvicauda may be more widely distributed.  The result that the major RLN species from Darkan had close sequence identity to the newly characterised RLN P. curvicauda  indicates that more RLN species impact broadacre crops in WA than previously thought.  We plan to re-isolate RLNs from the original sites where P. quasitereoides was first identified to undertake more molecular and morphological analyses to gain a better understanding of the RLN species that impact these sites.

References:

  1. Begum, F., Jones, M.G.K. and Fosu‐Nyarko, J. 2020. Assessment of the pest status of Pratylenchus curvicauda and ultrastructural changes in roots of infected wheat and barley. Plant Pathology, 69(8), pp.1574-1588.
  2. Hodda, M., Collins, S.J., Vanstone, V.A., Hartley, D., Wanjura, W. and Kehoe, M. 2014. Pratylenchus quasitereoides n. sp. from cereals in Western Australia. Zootaxa, 3866(2), pp.277-288.

Acknowledgement: PhD scholarship support by the Grains Research and Development Corporation


Biography:
Rhys is undertaking PhD research at the Western Australian State Agricultural Biotechnology Centre, Murdoch University. His background is in plant-pathogen interactions, having completed Honours research at Murdoch in 2017, focusing on identifying and characterising putative parasitism genes of the root lesion nematode Pratylenchus neglectus.

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