Why the Irish Potato Famine was not caused by a fungus

During the long, wet summer of 2012 (perfect late blight weather!), I gave a short public talk about the potato and late blight as part of the Taste of West Cork Festival in Skibbereen, Co. Cork.

The panel of speakers also included the excellent and informative broadcaster Éanna ní Lamhna (of RTE radio fame) who spoke about the history of the potato as well as the history of the Irish potato famine.

Despite the argument that political and economic issues had a great role to play in the Irish potato famine, there is no doubt that the loss of the potato crop due to late blight was the trigger that started it all.

Late blight was, and is, caused by the plant-pathogenic organism Phytophthora infestans which, unfortunately, many people describe as a 'fungus'.

Éanna ní Lamhna described it as such during her talk and I, humorously and good-naturedly (I think!), pulled her up on it. As you can imagine, given that much of the audience had come to see and hear the delightful Ms. ní Lamhna and not some young upstart like me, I had to thread very carefully and there was much friendly banter.

Speakers at the 'Humble Spud' talk

You can't blame anyone for making the mistake - P. infestans is often described as a fungus by those who really should no better.

Browsing through the excellent Atlas of the Great Irish Famine (Cork University Press) recently, I noticed the disease-causing organism is described in several places therein as a 'fungus'.

In a news report in a January issue of the journal Nature, P. infestans was described as "an organism similar to, and often grouped with, fungi". If the author meant that it is often grouped or lumped-in with fungi on a casual (and incorrect!) basis, she's quite right, but as we now know, the organism is not grouped (i.e. classified) as a fungus by fungal taxonomists.

The minutiae of fungal taxonomy is not something we should get bogged down in here (although some would argue that that boat has sailed!), but P. infestans is classified as an oomycete and can be found in the same kingdom as the brown algae and diatoms. Although it may have started out in the Fungi kingdom, it is now firmly categorised as a 'fungal-like organism'.

Damage caused by late blight of potato (APSNET)

A letter in this week's issue of Nature, taking issue with the original news report, states: "It was Anton de Bary, the father of mycology, who coined the genus name Phytophthora ('plant-destroyer') and classed the pathogen as a fungus. But modern molecular sequencing indicates that his interpretation was incorrect"

"The organism is actually an oomycete, a pseudo-fungus that evolved from killer ancestors in the ancient oceans and not from wood-degrading fungi", concluded the author.

Within mycology (the study of fungi), there is some debate over the use of the term fungus. While none would argue against the weight of molecular evidence that clearly puts P. infestans outside the Kingdon, some would argue that, since they are of interest to mycologists and they share many of the common morphological features of fungi, a broader defintion of the term is required.

Money (1998) has argued that the term fungus should have two distinct meanings: (1) the strict taxonomic name used to describe organisms from the Kingdom Fungi and (2) a practical reference to organisms studied by mycologists that share similar characteristics to fungi.

Somehow, I think the taxonomists would disapprove, and so would I.

GM Potato set to be planted in Ireland

A major new EU study is set to examine the effects of growing GM, blight-resistant potato plants on biodiversity and the environment in agricultural ecosystems. It will also see the first GM crops being grown in Ireland since the late 1990's.

In a statement issued at the end of February, Teagasc (the Irish agricultural development agency) announced that they are to seek a license to carry out field trials of GM potatoes as part of the AMIGA consortium - a group including representatives of research bodies from 15 EU countries.

Late Blight, caused by the fungal-like organism Phytophthora infestans, decimated the Irish potato crop  in the 1840s leading to the Great Famine. Since then, it has remained a problem for Irish farmers, requiring chemical fungicides to be used to maintain Irish potato yields. GM potatoes have the potential to protect the potato plant from Late Blight attack without the necessity for large amounts of fungicide to be applied.

The potato variety Desiree was transformed withe the Rpi-vnt1.1 gene which confers broad spectrum resistance to Phytophthora infestans. That gene, along with its own promoter and terminator regions were taken from the wild potato species Solanum venturii and inserted into the cultivated potato using Agrobacterium tumefaciens-mediated transformation.

While there are indications that public concern over GM crops has declined in the UK, the news that field experiments will be carried out in Ireland for the first time since the late 1990s has drawn some criticism here.

In a statement released last week, Irish Organic Farmers and Growers Association (IOFGA), called the experiments planned for Teagasc's Oakpark headquarters a waste of taxpayers money. "In light of the fact that Teagasc has lodged an application with the EPA (Environmental Protection Agency) for a licence to grow GM potatoes at its headquarters in Oakpark, IOFGA are demanding that Teagasc be held accountable for their decision to waste taxpayers money on this project."

File Photo: Minister Ruairi Quinn at an Anti-GM event last year

Grace Maher, Development Officer with IOFGA said that considering growing GM in Ireland is "economic suicide" and that the move would put at risk an export market worth 9.1 billion: "Ireland has an excellent reputation internationally as a clean green island that is also a GM free region, and we need to build on this reputation not destroy it”.

The statement ends by accusing Teagasc of pedalling an "unwanted technology":
"In this austere economic climate we need to end wasteful public spending immediately and enforce accountability on those who continue to do so."

Unfortunately, it seems the lobby group for the organic industry, is jumping the gun a bit here.

The funding comes directly from the EU's FP7 research programme - a €50 billion fund specifically designated for research and technological development. There is no question of further money coming from Irish taxpayers.

No matter where the money comes from, there is also a wider issue. Teagasc is Ireland's agriculture and food development agency. It is that organisation's role to carry out research leading to a better understanding of agriculture and new agronomic techniques. To accuse such a body of "wasting" money by doing the very thing is was set up to do, is ridiculous. Any arguments for or against GM crops need to be based on firm scientific evidence and that does not simple fall out of the sky.

The field tests to be carried out at Oakpark will look at the impact of GM plants on the surrounding ecosystem and John Spink, Head of Crops Research at Teagasc was keen to point out that the research is "not about testing the commercial viability of GM potatoes".

"The GM study is about gauging the environmental impact of growing GM potatoes in Ireland and monitoring how the pathogen, which causes blight, and the ecosystem reacts to GM varieties in the field over several seasons.”

Mindful of the controversy surrounding trials of GM sugar beet in Ireland in the late 1990s by Monsanto, these new experiments will use a potato developed at Wageningen University in the Netherlands and there will be no biotech or GM company involved. The sugar beet trials ended with a number of the sites being destroyed by a group styling itself the Gaelic Earth Liberation Front.

According to documents submitted to the EPA as part of the licence application, the field experiments are designed to measure the impact of GM potato cultivation on bacterial, fungal, nematode and earthworm diversity in the soil compared to a conventional system; to identify positive or negative impacts of GM potato on integrated pest management systems; and to use the project as a tool for education in order to engage and discuss the issues surrounding GM with stakeholders and the public.

As Teagasc researcher Dr. Ewen Mullins put it: “It is not enough to simply look at the benefits without also considering the potential costs. We need to investigate whether there are long term impacts associated with this specific GM crop and critically we need to gauge how the late blight disease itself responds. This is not just a question being asked in Ireland. The same issues are arising across Europe.”

Speaking to the Irish Examiner, Dr. Mullins remarked: "People are asking about the merits of GM potatoes.At Teagasc, we have a remit to inform people. We haven’t had GM field trials here since the late 1990s. The goal is to look at all of the environmental impacts, and to fill the vacuum that exists currently in terms of impartial knowledge."

An edited version of this article appears on the Guardian's Notes and Theories blog. You can read it here.