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What did you find?

We studied two different races of the Irish potato famine pathogen, and we discovered that the difference invirulence between these races could not be ascribed to a genetic difference but rather to a difference in the expression of the underlying virulence gene. This adds to our knowledge of how this important scourge on world agriculture evolves to evade plant immunity.

Why is this work important?

As our colleague Mark Gijzen tweeted, “is this a rare and unusual curiosity or another example of a widespread biological phenomenon?” Indeed, there are few other examples in related plant pathogens, including the soybean root rot pathogen that Mark studies. This finding has far reaching implications. It indicates that these pathogens can evolve even more rapidly than anticipated thus counteracting the efforts of plant breeders to deploy disease resistant crops.

Are potato varieties resistant to the pathogen available?

Yes, there are. But there are several examples of potato cultivars that were initially resistant to late blight when farmers started to grow them, but succumbed to the disease a few years later. The ability to switch on and off virulence genes such as we found in this research may partly explain why the pathogen is so effective at overcoming the plants defense barriers.

There are potato varieties initially resistant to Phytophthora infestans that have succumbed to late blight a few years later.

What is currently done to control the disease?

Susceptible potato cultivars must be protected by repeated applications of fungicides. If left unchecked, the disease will destroy the leaves and stems in a matter of days as in the pictured trial plot of potato varieties in the highlands of Peru.

Is chemical protection the only way to control late blight?

In nature, there are wild relatives of the cultivated potato and many of them can withstand the disease (see image of potato variety field trial). Breeders identify the genes in these plants and introduce them to cultivated potato through crosses or genetic transformation.

How did you put this project together?

We studied an Andean lineage of the Irish potato famine pathogen known as EC-1 so the project had an international flavor from day one. Ours was a wide reaching multinational collaboration bringing together scientists based in the UK, Japan, Netherlands, USA, Philippines, and Peru. It’s how science often goes on these days. Experts from all over the world team up to solve problems, make new discoveries and advance our knowledge.

Anything you would have done differently?

DNA sequencing technology develops so fast that by the time the paper gets published you wish you could apply a different method. It also takes more time to analyze the data, write up the paper etc. than to generate the sequence data. This can be frustrating.

You posted the paper in bioRxiv before submission. Why?

Why not? Posting the article on bioRxiv enabled us to share our findings with our colleagues and hear about it from the community as soon as possible. The tweet by Mark Gijzen we referred to above is an example of such feedback. Posting a preprint relieves some of the delays associated with publishing. It’s a liberating feeling to finish writing up a paper and immediately share it with anyone who’s interested.

Authors

Dr. Vivianne Vleeshouwers is assistant professor in Wageningen University & Research, the Netherlands. Her research is dedicated to understand the molecular interaction between the potato late blight pathogen Phytophthora infestans and potato, and exploit this knowledge to achieve a better and more durable disease resistance.

Dr. Hannele Lindqvist-Kreuze works as a Molecular Breeder at the International Potato Center (CIP) in Lima, Peru. Her current work focuses on the discovery and application of molecular markers in the potato and sweet potato breeding programs of CIP. She describes her work as a Haiku: Searching for Hidden Patterns, Coded in the DNA, Unknowingly selected.

Dr. Sophien Kamoun is a Senior Scientist at The Sainsbury Laboratory and a Professor of Biology at the University of East Anglia in Norwich, UK. He studies the interactions between plants and filamentous pathogens, notably the Irish potato famine pathogen and the rice and wheat blast fungus. He’s known for saying “Don’t bet against the pathogen.”