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115R471 PhD Characterising PCN Populations

Publication Date: 
25 April 2019
Author/Contact :
Author/Contact: 
Matt Back

Contractor :
Contractor: 
Harper Adams University

Full Research Project Title: Characterisation of Potato Cyst Nematode Populations in Great Britain for Sustainable Crop Management
Duration: October 2013 - September 2018

Aims and Objectives

Aim: To characterise PCN populations of Great Britain by examining the distribution of species, virulence and viability.

Objectives:

a. Conduct a survey of UK PCN populations in order to produce a current distribution map
b. Using the PCN samples from the survey, examine the virulence of G. pallida populations using different sources of resistance
c. Determine the best method for assessing PCN viability and develop a rapid and universal test
d. Evaluate the viability test under field conditions following inputs such as nematicide application and biofumigation
e. Using the PCN samples from the survey, examine the viability of the populations in relation to field history

 

A stratified survey was conducted in England and Wales based on the total ware potato growing area. The aim was to collect 500 soil samples comparable to that reported in a previous survey (Minnis et al, 2002). The samples were systematically distributed across 34 counties. Samples were taken from 1 ha blocks

  • Potato cyst nematodes were detected in 48% of samples obtained from ware potato growing land in England and Wales.
  •  Identification of PCN species from positive survey samples collected in England and Wales showed that 6% populations contained both species (mixed), 89% populations were pure G. pallida and 5% populations were pure G. rostochiensis.

Samples of 9 G. pallida field populations from the survey were selected for pathotype determination virulence tests. A range of potato genotypes, including a susceptible control and genotypes representing the main sources of resistance towards G. pallida pathotypes Pa1 and partial resistance towards Pa2/3, were used. 8 of the 9 samples could be assigned to pathotype Pa2/3. The remaining sample had high Pf/Pi ratios across all genotypes and could not be designated to G. pallida pathotype Pa1 or Pa2/3.

Determining the viability of eggs within the cysts is essential for assessing the effectiveness of control treatments and making decisions on inputs. The student assessed various techniques for estimating viability under identical conditions to identify the most reliable assay. Comparison of the assays showed that hatching in Potato Root Diffusate and a trehalose quantification assay mostly correctly detected samples containing non-viable nematodes.

Mitotype diversity assessment was attempted for a sub-set of the field samples however the approach was not successful and plans have been made to run a repeat of the sequencing.

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