# The potato cyst nematode Globodera pallida overcomes major potato resistance through selection on standing variation at a single locus

## TL;DR

This study shows how a potato nematode evolves to overcome resistance by selecting on a single genetic locus.

## Contribution

The paper identifies a specific avirulence gene, Gp-pat-1, responsible for nematode adaptation to potato resistance.

## Key findings

- GpaV vrn resistance in potatoes is being overcome by selection on standing genetic variation in G. pallida.
- Gp-pat-1 is an avirulence gene whose silencing increases virulence on resistant potato varieties.
- Negative selection on Gp-pat-1 is driving the emergence of virulent nematode populations in the field.

## Abstract

Globodera pallida poses a major threat to potato production, with management strategies primarily relying on genetic resistance. However, increasing virulence in field populations across Western Europe raises major concerns for G. pallida control.To investigate the evolutionary mechanisms driving this rise in virulence, we propagated 13 field populations on 30 commercial potato varieties. Our findings indicate that the genetic basis of resistance in potatoes is small, with the major resistance conferred by GpaV from Solanum vernei. The wide application of GpaV

vrn
has led to continuous selection on standing genetic variation in G. pallida.To map virulence, we propagated two field populations on a GpaV

vrn
‐resistant variety for five generations. High‐coverage whole‐genome sequencing of each generation revealed that GpaV

vrn
‐mediated selection acted on a single locus of a newly assembled G. pallida Rookmaker reference genome. Examination of this virulence‐associated locus identified Gp‐pat‐1 as a candidate gene. Silencing Gp‐pat‐1 increased virulence on a GpaV

vrn
‐resistant variety but had no effect on nematode virulence on a susceptible variety, classifying Gp‐pat‐1 as an avirulence gene.Our findings show that GpaV

vrn
‐mediated negative selection on Gp‐pat‐1 is driving the emergence of virulence and improves our understanding of resistance breakdown and the evolutionary dynamics of nematode adaptation in the field.

Globodera pallida poses a major threat to potato production, with management strategies primarily relying on genetic resistance. However, increasing virulence in field populations across Western Europe raises major concerns for G. pallida control.

To investigate the evolutionary mechanisms driving this rise in virulence, we propagated 13 field populations on 30 commercial potato varieties. Our findings indicate that the genetic basis of resistance in potatoes is small, with the major resistance conferred by GpaV from Solanum vernei. The wide application of GpaV

vrn
has led to continuous selection on standing genetic variation in G. pallida.

To map virulence, we propagated two field populations on a GpaV

vrn
‐resistant variety for five generations. High‐coverage whole‐genome sequencing of each generation revealed that GpaV

vrn
‐mediated selection acted on a single locus of a newly assembled G. pallida Rookmaker reference genome. Examination of this virulence‐associated locus identified Gp‐pat‐1 as a candidate gene. Silencing Gp‐pat‐1 increased virulence on a GpaV

vrn
‐resistant variety but had no effect on nematode virulence on a susceptible variety, classifying Gp‐pat‐1 as an avirulence gene.

Our findings show that GpaV

vrn
‐mediated negative selection on Gp‐pat‐1 is driving the emergence of virulence and improves our understanding of resistance breakdown and the evolutionary dynamics of nematode adaptation in the field.