PPB with Gardeners

The keenness of gardeners to get involved in plant breeding has long been known. During the 1950s, tens of thousands of gardeners in the USA submitted marigolds to the Burpee seed company in a competition to find a white one.

But, despite this, gardeners have actually been very hard for plant breeders to work with.

The biggest problem is that, in a single country, there may be millions of them, often with few commonalities. This diversity makes it difficult – but also all the more essential – to get a representative sample.

Most gardeners also aren’t linked in any way, for example, through an association. Fortunately, the World Wide Web solves this: websites, internet, social networks etc make it easy and cheap now to work with many people.

Another problem of gardeners is that most have only small gardens so they don’t have much land for growing seedlings – yet breeders usually want to grow hundreds, if not thousands, of these. But again, computers plus modern statistics are now able to analyse thousands of little bits of data.

So, it is now practical. Here are the examples I’ve found.


The Guild of Oca Breeders

This is a web-based plant breeding club started in the UK around 2015 by Dr Owen Glyn Smith at Plymouth University.

Oca comes from the tropical highlands (Andes) of S. America and has an underground tuber, like the potato. It has been grown only a short time at high latitudes, for example, in lowland UK and Europe.

As a result, it remains adapted to produce tubers only in short daylengths experienced during the growing season in the Tropics; in the UK it produces tubers only in late autumn.

The Guild of Oca Breeders uses PPB with gardeners to breed varieties of oca that develop tubers in the long days of a European summer. Gardeners are recruited using its website and they make a small payment to be involved.

The Guild does all the crossing and grows the seedlings to produce tubers. It sends these to its members to grow in their gardens for their assessment and to return any really good ones.

Members have to sign the Open Source Seed Initiative pledge, so receiving plant material is a commitment to keeping the germplasm in the public domain.

Unfortunately, this initiative seems at least temporarily (2019) to have fallen foul of official regulations to prevent the spread of diseases on vegetatively-propagated planting material; apart from this, the idea seems brilliant!

1000 Gardens Soybean Breeding Project

This soybean breeding project combines a German specialist manufacturer of tofu called Taifun-Tofu GmbH, the German University of Hohenheim State Plant Breeding Institute, and German gardeners.

The aims of the project are to expand the cultivation of soybeans in cooler regions of Germany by breeding cool-tolerant varieties suitable for tofu production.

A condition of being a part of the project is that the intellectual property rights of the breeding lines remained with Taifun-Tofu GmbH and the State Plant Breeding Institute.

In 2016, the project received online registrations from around 2,500 gardeners. About half remain committed, sending in their data (plant height, ripening date etc) online and posting their harvest by surface mail.

The beans are analysed by scientists and all data is shared online with the gardeners. This includes lots of photographs (see below) and explanations to maintain interest (Wurschum et al., 2019).

And these photos illustrate that, once again, everyone is enjoying themselves as well as doing something beneficial. But what seems truly ground-breaking about this project is its recruitment of so many gardeners via the internet!

Citizen scientists at work. A collection of impressions of the volunteer soybean gardeners at work, uploaded by themselves. Credit: Wurschum et al, 2019

Lettuce breeding with gardeners

Downy mildew (Bremia lactucae) is perhaps the most important diseases of lettuce. Over thirty strong and dominant resistance genes (Dm genes) able individually to control the disease have been identified in mainly wild lettuce species and these have been used, sometimes in combination with fungicide, to provide control. However, both means of control have been broken as more virulent strains have repeatedly and rapidly evolved. One way being tried of controlling the disease is to ‘stack’ several of these strong resistance genes in a single variety.

However, quantitative resistance based on the presence of many but weaker resistance genes has also been identified in mainly heirloom varieties of lettuce and may, like the example of Sarpo Mira potato and late blight, provide a more durable resistance. This is the route an organic, not-for-profit Swiss seed company, Sativa Rheinau AG, and gardeners throughout Europe have taken in the development of new lettuce varieties.

Parental lines are selected from mildew-tolerant traditional varieties by plant breeders at Sativa and crossed. Then, “In order for the lettuce to come into contact with a large number of different mildew strains, it is necessary for the lettuce lines to be cultivated at a large number of [garden] locations in Central Europe.”

Like the soybean project, some 1,200 gardeners were involved by 2020 but what is really impressive with this project is that, like the Dwarf Tomato Project, it has become international with gardeners in many European countries involved and a French website.

The location in Europe of the thousands of gardeners who contributed (by 2020) to Sativa Rheinau’s trials on mildew-resistant lettuces. Image credit: Sativa Rheinau
Crossing lettuce varieties selected by gardeners at Sativa Rheinau. Image credit: Sativa Rheinau

Like the soybean project, they include photographs and explanations on the project’s websites and feedback to the gardeners to maintain their enthusiasm.

Because Sativa Rheinau AG is a small company, the participatory breeding must cover its costs! And it already breeds vegetable varieties for gardeners conventionally and therefore understands these costs.

Sativa Rheinhau also says it is intending PPB to be a part of their future! The method is clearly practical.

Overall progress of PPB with gardeners

The above three examples are farsighted and extraordinarily hopeful. It’s taken a long time but the idea seems so simple and logical. And there are lots of other institutions that could follow the same pathway.

In the UK, we also have similar organisations. The Seed Co-operative is an organic and bio-dynamic seed company owned by its members and Real Seeds is a small seed company that provides advice on seed saving, the action of a company wanting to make only an ethical amount of profit. The National Institute of Agricultural Botany includes “NIAB EMR, at East Malling in Kent [working] on perennial fruit crops. [Its] research programme is based on genetics, genomics and breeding [my italics]”.

And many other developed countries have a similar range of institutions with breeding expertise.

I want to move on though to one major criticism of the three examples given of PPB with gardeners. They all try very hard to involve gardeners as much as possible but, although gardeners provide much of the data, they aren’t making the really important decisions such as choosing the crop or the traits to breed for.

But that would occur if the gardeners provided the leadership. There are lots of gardeners and lots of gardening clubs of different forms and sizes. And some have lots of resources and would seem able to provide leadership.

For example, my allotment half-plot (above) is in a site of over a hundred and fifty plots. The site is managed by a society which also manages two others, so perhaps three hundred plots in total. It also has a shop, Facebook website and email addresses of most members so we are relatively easy to contact.

And bigger cities have bigger organisations with more sites: the Greater London Authority looks after 763 allotment and community growing sites! There are also regional associations, for example, The Yorkshire Allotments and Gardens Federation.

Even higher, there is the UK National Allotment Society (NSALG). And NSALG belongs to the Europe-wide International Office of Allotment and Leisure Gardens (Office International du Coin de Terre et des Jardins Familiaux) in Paris.

In its newsletter, I came across the statistics that Dresden in Germany, with a population of around half a million people, has 25,000 allotments in 366 sites and occupying 793 ha and Hamburg, with a population of nearly two million people has 34,780 allotments in 312 sites occupying 1,829 ha.

Any one of those levels could organise participatory plant breeding with a local horticultural college, university or institute! And gardeners would be taking the lead.

My allotment society also doubles as a horticultural society and there are about three thousand such local societies in England affiliated to the Royal Horticultural Society (RHS), with hundreds of thousands of members. The RHS has “Understanding and promoting the benefits, use [my italics] and conservation of plant genetic resources in UK gardens” on its website.

There are also several horticultural colleges and universities with horticultural leanings dotted across the UK, at least some of which would surely be interested in partnering gardeners in PPB. And similar institutions are replicated, sometimes in slightly different forms, in most developed countries at least.

But, if it is so good, why isn’t everybody doing it?

Well, it mostly comes back to ownership of plant genetic resources.

In all the above examples, none involves a commercial plant breeding company (Taifun-Tofu GmbH is a commercial company but it is more interested in extracting tofu and similar products from soybeans than in selling soybean varieties). All the others involve governments, universities, overseas aid or a not-for-profit company. Legal agreements can retain ownership for commercial companies if all participants are worth suing (e.g., Dutch potato farmers perhaps) but these seem not strong enough to tempt most commercial breeding companies into PPB.

So, in PPB, gardeners and other users tend to be partnered with institutions for which ownership of plant varieties is less important, for example, not-for-profit companies, charities, universities and government institutes. We should therefore expect this trend to continue and prioritise such partners.

But we shouldn’t give up on at least small for-profit plant breeding companies, cooperatives or seed retailers; some may be attracted by the benefits of PPB for at least a portion of their activities.

So, I think: It’s ‘all to play for!’