Fighting Fusarium wilt to beat the bananapocalypse

Dr. Sarah Schmidt (@BananarootsBlog), Researcher and Science Communicator at The Sainsbury Laboratory Science. Sarah got hooked on both banana research and science writing when she joined a banana Fusarium wilt field trip in Indonesia as a Fusarium expert. She began blogging at https://bananaroots.wordpress.com and just filmed her first science video. She speaks at public events like the Pint of Science and Norwich Science Festival.

 

Every morning I slice a banana onto my breakfast cereal.

And I am not alone.

Every person in the UK eats, on average, 100 bananas per year.

Bananas are rich in fiber, vitamins, and minerals like potassium and magnesium. Their high carbohydrate and potassium content makes them a favorite snack for professional sports players; the sugar provides energy and the potassium protects the players from muscle fatigue. Every year, around 5000 kg of bananas are consumed by tennis players at Wimbledon.

But bananas are not only delicious snacks and handy energy kicks. For around 100 million people in Sub-Saharan Africa, bananas are staple crops vital for food security. Staple crops are those foods that constitute the dominant portion of a standard diet and supply the major daily calorie intake. In the UK, the staple crop is wheat. We eat wheat-based products for breakfast (toast, cereals), lunch (sandwich), and dinner (pasta, pizza, beer).

In Uganda, bananas are staple crops. Every Ugandan eats 240 kg bananas per year. That is around 7–8 bananas per day. Ugandans do not only eat the sweet dessert banana that we know; in the East African countries such as Kenya, Burundi, Rwanda, and Uganda, the East African Highland banana, called Matooke, is the preferred banana for cooking. Highland bananas are large and starchy, and are harvested green. They can be cooked, fried, boiled, or even brewed into beer, so have very similar uses wheat in the UK.

In West Africa and many Middle and South American countries, another cooking banana, the plantain, is cooked and fried as a staple crop.

In terms of production, the sweet dessert banana we buy in supermarkets is still the most popular. This banana variety is called Cavendish and makes up 47% of the world’s banana production, followed by Highland bananas (24%) and plantains (17%). Last year, I visited Uganda and I managed to combine the top three banana cultivars in one dish: cooked and mashed Matooke, a fried plantain and a local sweet dessert banana!

 

Three types of banana in a single dish in Uganda.

Another important banana cultivar is the sweet dessert banana cultivar Gros Michel, which constitutes 12% of the global production. Gros Michel used to be the most popular banana cultivar worldwide until an epidemic of Fusarium wilt disease devastated the banana export plantations in the so-called “banana republics” in Middle America (Panama, Honduras, Guatemala, Costa Rica) in the 1950s.

Fusarium wilt disease is caused by the soil-borne fungus Fusarium oxysporum f. sp. cubense (FOC). The fungus infects the roots of the banana plants and grows up through the water-conducting, vascular system of the plant. Eventually, this blocks the water transport of the plant and the banana plants start wilting before they can set fruits.

Fusarium Wilt symptoms

Fusarium Wilt symptoms

The Fusarium wilt epidemic in Middle America marked the rise of the Cavendish, the only cultivar that could be grown on soils infested with FOC. The fact that they are also the highest yielding banana cultivar quickly made Cavendish the most popular banana variety, both for export and for local consumption.

Currently, Fusarium wilt is once again the biggest threat to worldwide banana production. In the 1990s, a new race of Fusarium wilt – called Tropical Race 4 (TR4) – occurred in Cavendish plantations in Indonesia and Malaysia. Since then, TR4 has spread to the neighboring countries (Taiwan, the Philippines, China, and Australia), but also to distant locations such as Pakistan, Oman, Jordan, and Mozambique.

Current presence of Fusarium wilt Tropical Race 4. Affected countries are colored in red.

In Mozambique, the losses incurred by TR4 amounted to USD 7.5 million within just two years. Other countries suffer even more; TR4 causes annual economic losses of around USD 14 million in Malaysia, USD 121 million in Indonesia, and in Taiwan the annual losses amount to a whopping USD 253 million.

TR4 is not only diminishing harvests. It also raises the price of production, because producers have to implement expensive preventative measures and treatments of affected plantations. These preventive measures and treatments are part of the discussion at The World Banana Forum (WBF). The WBF is a permanent platform for all stakeholders of the banana supply chain, and is housed by the United Nation’s Food and Agricultural Organization (FAO). In December 2013, the WBF created a special taskforce to deal with the threat posed by TR4.

Despite its massive impact on banana production, we know very little about the pathogen that is causing Fusarium wilt disease. We don’t know how it spreads, why the new TR4 is so aggressive, or how we can stop it.

Fusarium Wilt symptom

Fusarium Wilt symptoms in the discolored banana corm.

Breeding bananas is incredibly tedious, because edible cultivars are sterile and do not produce seeds. I am therefore exploring other ways to engineer resistance in banana against Fusarium wilt. As a scientist in the 2Blades group at The Sainsbury Laboratory, I am investigating how we can transfer resistance genes from other crop species into banana and, more recently, I have been investigating bacteria that are able to inhibit the growth and sporulation of F. oxysporum. These biologicals would be a fast and cost-effective way of preventing or even curing Fusarium wilt disease.

 

Twitter:           @BananarootsBlog

Email:              mailto:[email protected]

Website:          https://bananaroots.wordpress.com

How diverse is your food?

Dr Colin Khoury

Dr Colin Khoury

This post was written by Dr Colin Khoury. Colin studies diversity in the crops people grow and eat worldwide, and the implications of change in this diversity on human health and environmental sustainability. He is particularly interested in the wild relatives of crops. Colin is a research scientist at the International Center for Tropical Agriculture (CIAT), Colombia, and at the USDA National Laboratory for Genetic Resources Preservation in Fort Collins, Colorado.

 

New Changing Global Diet website explores changes in diets over the past 50 years in countries around the world.

One of the central concepts that unifies those concerned with biodiversity is the understanding that this diversity is being lost, piece by piece, to a greater or lesser degree, globally.

The same goes for the biodiversity of what we eat. Scientists and activists have worried about the loss of crops and their many traditional varieties for at least a hundred years, since botanist N. I. Vavilov traveled the world in search of plants useful for cultivation in his Russian homeland. He noticed that diversity was disappearing in the cradles of agriculture – places where crops had been cultivated continuously for thousands of years. The alarm sounded even louder 50 years ago, during the Green Revolution, when farmers in some of the most diverse regions of the world largely replaced their many locally adapted wheat, rice and other grain varieties with fewer, more uniform, higher yielding professionally bred varieties.

 

Map of crop diversity

Cradles of agriculture: origins and primary regions of diversity of agricultural crops

(Click to magnify)

 

This is ironic, since modern productive crop varieties are bred by wisely mixing and matching diverse genetic resources. The disappearance of old varieties thus reduces the options available to plant breeders, including those working to produce more nutritious or resilient crops.

Being a food biodiversity scientist, I grew up (in the professional sense) with the loss of crop diversity looming over my head, providing both a raison d’être, and an urgency to my efforts. Somewhere along the line, I became interested in understanding its magnitude. That is, counting how many crops and how many varieties have been lost.

That’s where it started to become complicated, and also more interesting. Because, when I went looking for signs of the loss of specific crops, I couldn’t find any. Instead, I found evidence of massive global changes in our food diversity that left me worried, but at the same time hopeful.

A bit of background. Most of the numbers seen in the news on how much crop diversity has been lost go back to a handful of reports and books that reference a few studies: for example, the changing number of vegetable varieties for sale in the U.S. over time. The results are estimations for a few crops at local to national levels, but they somehow have been inflated to generalized statements about the global state of crop diversity, the most common of which being some variation of “75% of diversity in crops has been lost”.

Market stand of fruit and vegetables

Diverse produce, but is it all local? Image credit:  Karyn Christner. Used under license: CC BY 2.0.

Putting true numbers on diversity loss turns out to be a complicated and contested business, with no shortage of strong opinions. One big part of the problem is that there aren’t many good ways to count the diversity that existed before it disappeared. Researchers have done some work to assess the changes in diversity in crop varieties of Green Revolution cereals, and to some degree on the genetic diversity within those varieties. The results indicate that, although diversity on farms decreased when farmers first replaced traditional varieties with modern types, the more recent trends are not so simple to decipher.

It was particularly surprising to me that very little work had been done to understand the changes in what is probably the simplest level to measure: the diversity of crop species in the human diet, that is, how successful is maize versus rice versus potato versus quinoa and so on. I realized that data on the contribution of crops to national food supplies were available for almost all countries worldwide via FAOSTAT, with information for every year since 1961. Perhaps these were the data that could show when a crop fell off the world map.

Fast forward through a couple of years of investigation. To my great surprise, I found that not a single crop was lost over the past 50 years! There was no evidence for extinction. What was going on?

Maize

Maize is a key crop in many countries. Image credit: Erfan A. Setiawan. Used under license: CC BY 2.0.

It turns out that my failure to see any loss of crops was due to the lack of sufficient resolution in the FAO data. Only 52 meaningful crop species-specific commodities are measured and a number of these are general groupings such as “cereals, other”. Because of this lack of specificity, the data couldn’t comprehensively assess the crops that have been most vulnerable to changes in the global food system over the past 50 years. In FAO data, these plants are either thrown into the general categories or they aren’t measured at all, especially if they are produced only on a small scale, for local markets or in home gardens. This is, in itself, sign enough that they may be imperiled. We need better statistics about what people eat (and grow) around the world. But, enough is known to be confident that many locally relevant crops are in decline.

Over the past 50 years, almost all countries’ diets actually became more diverse, not less, for the crops that FAO statistics do report on. We found that traditional diets that were primarily based on singular staples a half century ago, for instance rice in Southeast Asia, had diversified over time to include other staples such as wheat and potatoes. The same was true for maize-based diets in Latin America, sorghum- and millet-based diets in sub-Saharan Africa, and so on.

Not that there weren’t plant winners and losers. Wheat, rice, and maize, the most dominant crops worldwide 50 years ago, became more important globally. Other crops emerged as widespread staples, particularly oilcrops such as soybean, palm oil, sunflower, and rapeseed oil. And, as the winners came to take more precedence in food supplies around the world, alternative staples such as sorghum, millets, rye, cassava, sweet potato, and yam were marginalized. They haven’t disappeared (at least not yet), but they have become less important to what is eaten every day.

As countries’ food supplies became more diverse in the winner crops reported by FAO, and the relative abundance of these crops within diets became more even, food supplies worldwide became much more similar, with an average decrease in variation between diets in different countries of 68.8% over the past 50 years!

This is why, although we could see no absolute loss in crops consumed over the past 50 years, I am concerned. For even in the relatively small list of crops reported in the FAO data, many of these foods are becoming marginalized, day by day, bite by bite. That doesn’t seem like a good thing for the long-term resilience of our agricultural areas, nor for human health, although it’s important to remember that such changes are the collateral damage resulting from the creation of highly productive mega-crop farming systems, which have increased the affordability of these foods worldwide, leading to less stunting and other effects of undernutrition worldwide. On the other hand, global dependence on a few select crops equates to expansive monocultures, with more lives riding on the outcome of the game of cat and mouse between pestilence and uniform varieties grown over large areas. Moreover, cheaply available macronutrients have contributed to the negative effects of the nutrition transition, including obesity, heart disease and diabetes.

So why then am I hopeful? Because the data, and some literature, and my own direct experience also indicate that diets in recent years, in some countries, are beginning to move in different directions, reducing the excessive use of animal products and other energy-dense and environmentally expensive foods, and becoming more diverse, particularly with regard to fruits and vegetables, and even healthy grains. What better evidence than quinoa, which was relatively unknown outside the Andes a couple of decades ago, and is now cultivated in 100 countries and consumed in even more?

When we published our findings of increasing homogeneity in global food supplies, we hadn’t yet found a good way to make the underlying national-level data readily visible to interested readers. This is why I’m tremendously excited to announce the publication of our new Changing Global Diet website, which provides interactive visuals for 152 countries over 50 years of change. We that hope you will enjoy your own investigations of dietary change over time. Perhaps you can tell us where you think the changing global diet is headed.

Check out The Changing Global Diet website


Read the published article: Khoury CK, Bjorkman AD, Dempewolf H, Ramírez-Villegas J, Guarino L, Jarvis A, Rieseberg LH and Struik PC (2014). Increasing homogeneity in global food supplies and the implications for food security. PNAS 111(11): 4001-4006.

Round-up of Fascination of Plants Day 2016

On May 18th, botany geeks around the world shared their love of plants in this year’s Fascination of Plants Day! Here’s our round-up of some of the best #fopd tweets!

First things first, test your skills with this challenging plant science quiz:

Check out some of the amazing work done by Botanic Gardens Conservation International (BGCI):

Have you read this thought-provoking post from The Guardian?

Check out these amazing ears of maize! 

Read on to learn how signals are converted to epigenetic memory:

More from BGCI:

Includes the amazing subheading “Ovules before brovules”!:

Great to hear from some of our younger plant scientists:

Some fun facts to share with your friends:

A fantastic image featuring the adaptations of marram grass to its sand-dune home:

This fascinating mutation results from an elongated apical meristem:

How long does this starch need to last? Plants use their internal circadian clock to ration their energy stores:

The loblolly pine’s genome is over seven times larger than yours!

Need more Fascinating Plants? There are lots of great ‘Roots and Shoots’ articles on eLife‘s Medium page

How did you celebrate Fascination of Plants Day this year? Let us know in the comments below!

A year at the Global Plant Council

Last April I joined the Global Plant Council as a New Media Fellow along with Sarah Jose from the University of Bristol. The GPC is a small organization with a big remit: to bring together stakeholders in the plant and crop sciences from around the world! As New Media Fellows, Sarah and I have have assisted in raising the online profile of the GPC through various social media platforms. We wrote about our experiences in growing this blog and the GPC Twitter and Facebook accounts in the The Global Plant Council Guide to Social Media, which details our successes and difficulties in creating a more established online presence.

 

Why do it?

My wheat growing in Norfolk field trials. I have spent every summer for the past 3 years out here analysing photosynthesis and other possible contributors to crop yield

My wheat growing in Norfolk field trials. I have spent every summer for the past 3 years out here analysing photosynthesis and other possible contributors to crop yield

I chose to apply for the fellowship during the third year of my PhD. Around this time I had started to consider that perhaps a job in research wasn’t for me. It was therefore important to gain experience outside of my daily life in the lab and field, explore possible careers outside of academia and of course to add vital lines to my CV. I still loved science, and found my work interesting, so knew I wanted to stay close to the scientific community. Furthermore, I had always enjoyed being active on Twitter, and following scientific blogs, so the GPC fellowship sounded like the perfect opportunity!

 

The experience

I think I can speak for both Sarah and myself when I say that this fellowship has been one of the best things I’ve done during my PhD. Managing this blog for a year has allowed me to speak to researchers working on diverse aspects of the plant sciences from around the world. My speed and writing efficiency have improved no end, and I can now write a decent 1000 word post in under an hour! I discovered the best places to find freely available photos, and best way to present a WordPress article. Assisting with Twitter gave me an excuse to spend hours reading interesting articles on the web – basically paid procrastination – and I got to use my creativity to come up with new ways of engaging our community.

Next career move, camera woman?

Filming interviews at the Stress Resilience Forum. Next career move, camera woman?

Of course going to Brazil for the Stress Resilience Symposium, GPC AGM and IPMB was a highlight of my year. I got to present to the international community both about my own PhD research and the work of the GPC, Sarah and I became expert camera women while making the Stress Resilience videos, and I saw the backstage workings of a conference giving out Plantae badges on the ASPB stand at IPMB. It didn’t hurt that I got to see Iguassu Falls, drink more than a few caipirinhas and spend a sneaky week in Rio de Janeiro!

Helping out on the ASPB stand

Helping out on the ASPB stand with Sarah

 

Thank you

Working with the GPC team has been fantastic. I learnt a lot about how scientific societies are run and the work they do by talking to the representatives from member societies at the AGM. The executive board have been highly supportive of our activities throughout. Last but not least, the lovely GPC ladies, Ruth, Lisa and Sarah have been an amazing team to work with – I cannot thank you enough!

I have now handed in my PhD, left the GPC, and moved on to a new career outside of academic research. I’m going into a job focused on public engagement and widening access to higher education, and have no doubt my GPC experiences have helped me get there. My advice if you’re unsure about where you want to end up after your PhD? Say “yes” to all new opportunities as you never know where they will take you.

Thank you the GPC! Hopefully I’ll be back one day!

 

Thank you! It's been amazing!

Thank you! It’s been amazing!