Towards a new tree-borne staple

Cotoneaster breeding

I’m back from my holiday break with an ambitious new plant breeding project.

In other news, I decided that I will offer my paid subscription as 50% off for the foreseeable future. You’ll see this if you ever decide to create a paid subscription. All my work, except my plant breeding projects, will fall behind a paid subscription membership after 6 months.

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The nights are getting longer now, and you’ve decided it’s time to light the fire. The roast is almost ready, another quarter of an hour should do it. You fancy a change from potatoes today - the harvest was pretty good but it can get monotonous - so you step out into the back garden with a wicker basket. You walk over to a shady spot where you planted a beautiful Sharavo Tree several years ago. You ordered this cultivar from your local food forest nursery, who provide robust grafted trees to anyone for a reasonable price.

The “Sharavo” was just one of the Cotoneaster cultivars on offer, another being “Xinan”. You recall the nursery owner telling you that these are local names, names of parent species that have intermingled their genes to create these delicious offspring and were themselves eaten by peoples in Asia. The owner said that this was a great way to honour those people and to carry on their traditions, and you found yourself agreeing whole-heartedly.

Apple sized fruits hang like red baubles from the elegantly arching herringbone branches, and you pause to admire the scene. A couple of Sharavo fruits each should suffice and you pluck them, one at a time, placing them lovingly in your willow wicker basket.

Back inside, you grate the red fruits and boil the mash in a little water for a ten minutes. A fragrant and subtle apple scent wafts into your face. You add a little seasoning into the Sharavo mash and place generous dollops onto some flat plates.

Time to carve the roast.

Just one of the many Cotoneaster species around my neighbour that has to potential to be the next food staple

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So what am I talking about here?

This is my second plant breeding project, and the little story I’ve written above sets the scene nicely for the end goal.

The goal is to breed a Cotoneaster that is particularly large and long lasting, which can be used as a food staple in the same way as a potato.

We will spend at least two articles discussing the worthiness of Cotoneaster as future food staple. I hope by the end of the series to have convinced you that it does deserve that crown and equally importantly how I plan to breed Cotoneaster into the future food that humanity deserves.

In this preliminary article, we will talk about why I think Cotoneaster is almost staple worthy in its wild form and also address some concerns regarding toxicity.

Staple worthy?

At least one species of Cotoneaster has remarkably high nutrient content. I’ll leave the details in the appendix, but my research has shown that compared to potatoes, C. nummularius (Asian Cotoneaster) has similar amounts of carbohydrates, more than twice as much protein, and more than thirty times the amount of fat. One area where the potato has Cotoneaster beat is vitamin C, with up to ten times the amount. Asian Cotoneaster is no slouch though, with almost twice as much calcium.

We can continue on and on, but my point is that Cotoneaster, has the potential to be another staple crop. In fact, one of the few blockers is the fruit size (small), and in this sense, improving the size of edible flesh is not dissimilar to breeding programs dedicated to increasing a walnut tree’s nut size.

Increasing the fruit size will decrease the harvest time, and as our story demonstrated, turns a chore into a delight.

The hidden but obvious question here is whether Cotoneaster has an acceptable taste. Whenever I’ve had Cotoneaster fruit, they’re quite bland and anecdotal chats tend to agree. Blandness can act as a nice tableau for other flavours. If the wild form - often the form with the strongest and most pungent flavours - is this innocuous then we have an extremely promising blank canvas for domestication.

A Poison Apple?

Cotoneaster’s cyanogenic glycoside content is something to be mindful of.

Cyanogenic glycoside breaks down in the body into hydrogen cyanide. The cyanide ion in this compound blocks your body’s ability to respire using oxygen. It then follows that the parts of your body that have a higher metabolic demand will be damaged first (such as the brain and the nervous system). Luckily, our body can process small amounts of hydrogen cyanide by converting it into another compound (thiocyanate, still not something to be trifled with) that passes out of us in our urine.

Consequences of overwhelming your body’s ability to process cyanide include nausea, vomiting, convulsions, stomach ache and in really high dosages: death.

In day to day life, humans will encounter cyanide by consuming natural products that contain cyanogenic glycoside. Famous examples of poisoning from this compound are, of course, eating a peach pit (one is possibly enough to kill you), apple pips (you’ll need to grind up and eat hundreds of seeds in one go to kill you), and perhaps more insidiously, cassava.

Cassava is a particular concern because it is the main staple for lots of impoverished people in arid locations. If you subsist entirely on cassava, you’ll develop a whole host of neurological and growth problems. Just look up “Konzo” and “Congenital iodine deficiency syndrome” for some nightmarish lessons in single food over reliance.

Am I undermining my own case for taming the Cotoneaster?

Not really, and here’s why.

The lesson for the consumer is simple: don’t over-rely on one staple. It’s a deceptively deep lesson, permeating all areas of life. Our failings in this one thing result in dangerously imbalanced monoculture fields, western malnutrition (corn, wheat or potatoes), gut flora imbalance and more.

The lesson for the plant breeder is also simple: do due diligence on your plant.

So, the question you’re dying (no pun intended) to ask is simply, what’s the cyanogenic glycoside content in Cotoneaster fruit?

The bad news is that this is a poorly researched topic, no doubt a reflection of how little it has been consumed even in times past.

The good news is what little research I found showed that Cotoneaster does not have anywhere near cassava levels of cyanogenic glycosides, and that simple methods exist to bring the levels down even further. In our little introduction story, we grate and boil the Sharavo fruit. In hotter climates, we could have sun dried the pulverised fruit. Fermentation also does the trick, amongst other methods.

If you’re worrying about the cyanogenic glycoside content of our future Sharavo Tree, then you would have some justification. We should be responsible with our health, so we should probably have some of the fruit tested in a lab before we start promoting our bred Sharavo Tree as a staple.

If it makes you feel any better, not even the WHO (World Health Organisation) can agree on safe levels of cyanogenic glycoside. According to one metric, the average child’s apple juice consumption exceeds the recommended safe dose by almost two-fold!

What is clear is that a balanced and reasonable diet is the best, but we knew that already!

So far, so good

So let’s wind it back and refocus:

The goal is to breed a Cotoneaster that is particularly large and long lasting, which can be used as a food staple in the same way as a potato.

We’ve addressed probably the biggest concern of all, that being the cyanogenic glycosides (cyanide) content of Cotoneasters. Along the way, we’ve learnt a fair amount about cassava. We’ve also addressed some doubts about the nutrient content by showing that Cotoneaster compares excellently to potato.

In the next post, we will expand further into the attributes that make Cotoneaster an attractive food staple, and how we can enhance these features to make it an enticing alternative dinner time proposition as we demonstrated in the Sharavo Tree in our introduction story.

Until next time.

Appendix

“Sharavo” is the name given by the indigenous people of the Thakht-e-Sulamian hills, itself located in the North-West tribal belt of Pakistan to Cotoneaster minitus. These people have a history of eating C. minitus directly.

“Xinan” is the Anglicization of the Chinese for southwest (西南). The Naxi, who live in Southwest China, have been known to directly consume Cotoneaster franchetti - which they call the Southwest Cotoneaster.

As a side by side, let’s compare one species, C. nummularius (Asian Cotoneaster), against the modern day potato.

Carbohydrate:

• Asian Cotoneaster - 65g per 100g (dry weight)

• Potato - 60-80g per 100g (dry weight)

Fat:

• Asian Cotoneaster - 17g per 100g (dry weight)

• Potato - 0.5g per 100g, (dry weight)

Fibre:

• Asian Cotoneaster - 15.5g per 100g (dry weight)

• Potato - 1.8g per 100g (boiled potato with skin)

Protein:

• Asian Cotoneaster - 12.4g per 100g (dry weight)

• Potato - ~4.5g per 100g (boiled potato with skin)

Calcium:

• Asian Cotoneaster - 0.87g per 100g (DW)

• Potato - 0.52g per 100g (DW)

References

• An overview of Cotoneaster species in Europe

• An Overview of the Genus Cotoneaster (Rosaceae): Phytochemistry, Biological Activity, and Toxicology

• Cotoneaster nummularius eaten in Pakistan, including detailed nutrient content breakdown.

• Cyanogenic glycoside content of a few Cotoneaster species and cassava

• A Review of Cyanogenic Glycosides in Edible Plants

• Public Health England, Hydrogen cyanide, toxicological overview

• Detoxification methods for cyanogenic glycosides

• WHO Technical Report Series 966, Evaluation of Certain Food Additives and Contaminants, Seventy-fourth report of the Joint FAO/WHO Expert Committee on Food Additives

• More about cassava in the modern world