Final report - PalAdapt project

Management of plant pests is probably the most serious challenge in sustainable food production and the maintenance of food security. Due to the strict regulation of or ban on major categories of pesticide, the potato cyst nematode G. pallida has been managed by a combination of crop rotation and the potato resistance locus Grp1, a relatively narrow range resistance gene which was introgressed into a range of commercial potato cultivars in Europe including Iledher, Seresta, Aveka, Innovator, Cardoso, Ivetta or Amanda. However, in 2014, G. pallida populations were described that can no longer be controlled by Grp1. Most likely similar highly virulent populations will also emerge in all major potato growing areas in North Western Europe where production practices are very similar

The PalAdapt project (2018-2020) has involved 8 scientists from three academic partners (INRAE, France; JKI, Germany; WU, Netherlands). The consortium conducted several knowledge dissemination actions and published an external scientific report to achieve a complete and broader dissemination of the results obtained during the project.

https://efsa.onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2020.EN-1874

In summary:

- Our results showed that all the virulent populations of G. pallida found to date in Europe seem to have adapted to potato resistance from already present populations and not to novel introductions from South America. Preliminary results also suggest that a single adaptation event occurred and resulted in the outbreaks reported in Germany and the Netherlands. This conclusion is in line with the fact that the virulence probably appeared in these regions because of the intensive use of resistant cultivars and the significant exchange of material between Germany and Netherlands, such as equipment.

- Miniaturized virulence tests that can be used as an alternative to laborious, time consuming and costly pot experiments. Miniaturized and in vitro tests give the same results as pot tests from a qualitative point of view but not from a quantitative point of view.

- We showed that virulent field populations found in Germany tend to have bigger cysts than their avirulent counterpart. Though some exceptions were observed, cyst size seems also to be impacted the same way in Peruvian field populations able to overcome the Grp1 resistance. However, additional experiments are needed before being able to recommend the use of cyst size monitoring as a proxy of Grp1 nematode virulence.

- Finally, thanks to a new G. pallida genome assembly produced in 2019, we have improved a previous set of candidate SNPs allowing the distinction of virulent and avirulent lineages of G. pallida selected in laboratory conditions. However, the first results obtained suggest that most of the candidate SNPs identified among the virulent and avirulent experimental lineages don’t vary the same way among virulent field populations. Further investigations on more natural populations are planned.