Determining the identity of Pratylenchus species in the WA Wheatbelt

Rhys G. R. Copeland1, Professor Mike 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.

Root-lesion nematodes (RLN) (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 collected from a cereal crop near Darkan, WA. Specific primers were used to amplify the D2-D3 region of the 28s rDNA sequence, and these amplicons were then cloned and sequenced. Phylogenetic relationships of the sequences with other Pratylenchus spp. were constructed by comparing them to a constructed database of 122 28S-D3 sequences representing 27 species of Pratylenchus from 24 regions worldwide. Phylogenetic trees constructed with the sequences aligned the samples with two Pratylenchus species: P. teres (55.5%) and P. curvicauda (44.4%). Of the phylogenetic trees conducted for RLNs from the Darkan site, sequences with a close relationship to that published for P. quasitereoides (Hodda et al., 2014) were not found. These results support the findings of Begum et al. 2019 and suggest that P. curvicauda may be more widely distributed. Another species identified in this project, P. teres, a nematode native to South Africa, was redescribed to P. quasitereoides for populations found in WA by Hodda et al. (2014). The identification of RLNs from Darkan with close sequence identity to P. curvicauda and P. teres but not P. quasitereoides may indicate that more RLN species impact broadacre crops in WA than previously thought. Next, we aim to re-isolate RLN’s from the original sites where P. quasitereoides was first identified to conduct futher molecular and morphological analysis to gain a better understanding of the species that impact these sites.
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

Rhys is currently undertaking PhD research at the Western Australian State Agricultural Biotechnology Centre, Murdoch University. He has a background of research in plant-pathogen interactions, having completed Honour’s research at the University in 2017, focusing on identifying and characterising putative parasitism genes of the root lesion nematode Pratylenchus neglectus.

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