Death to the hybrids — cancelling plant breeding technologies
Plant breeding has always been fraught with politics. But, it is still baffling to plant scientists why some technologies are readily adopted while others are rejected.
Cite as: Kamoun, S. (2022). Death to the hybrids — cancelling plant breeding technologies. Zenodo https://doi.org/10.5281/zenodo.6334667
“I’m not a scientist, I’m a breeder.”
Early in my career, I was left puzzled when a rather old fashioned speaker at a potato conference proudly proclaimed in their keynote lecture, “I’m not a scientist, I’m a breeder.” Their underlying argument at the time was that they viewed molecular markers as useless to the “art of potato breeding”.
This is nothing new under the sun. Luther Burbank — the famed American horticulturist and plant breeder — is credited with introducing over 800 plants to American horticulture and agriculture. But was he a scientist? He received accolades from certain academic corners, notably his unanimous election to honorary membership at the opening meeting of the American Breeders’ Association (ABA) at St. Louis in 1903, a learned society infamous for its ardent support of eugenics. Yet many scientists dispute whether Burbank actually followed a scientifc approach in his variety development and some even described him as a charlatan. Burbank’s work doesn’t come across as constrained by the rigors of the scientific method. His rejection of Mendelian genetics certainly doesn’t help his case. Perhaps the offending speaker at that potato conference was simply extending the romantic tradition of viewing plant breeding as an art form rather than the scientific discipline it should be.
This attitude may also be at the origin of the rejection of new technologies and knowledge, something I have witnessed over and over in some applied plant biology quarters. At the closing lecture of an applied plant pathology conference I attended over 10 years ago, the speaker made fun of the use of pathogen virulence effectors as tools for disease resistance screening despite the evidence. Other regularly ignore or down-play the value of genomics, of both crop and pathogen, in helping improve disease resistance breeding. Believe or not, I can understand where this attitude originates from. When your job is to deliver concrete results, you don’t have the luxury to experiment with unproven new approaches. This might also be a way of emphasizing the importance of tested and proven methods and know-how. A fear of losing expertise in a rapidly changing world.
Nonetheless, the potato breeder’s comment was puzzling at the time because it was evident that molecular markers and genomics-enabled approaches, were going to revolutionize plant breeding. And they have done just that. Leading plant breeding companies have fully embraced robotized genomic selection. Gene editing is now routine in plants, and the first commercial varieties have reached the market. And potato, that odd tetraploid plant, may be facing a total make-over with hybrid diploid potatoes becoming a reality on both sides of the globe. At a 2019 Plant Biology conference, Tom Osborn, Head of Vegetable Product Design at Bayer Crop Science, said “we’re hiring more data scientists than plant breeders these days.”
Vive La Résistance!
I was recently reminded of these issues following a message from my colleague Jeff Ellis FRS, an Australian plant scientist at CSIRO Plant Industry. Jeff is a pioneer in the field of plant disease resistance and a francophile, so it was no surprise that he shared this photo of a Bas Armagnac called RESISTANCE. Armagnac is a type of spirit distilled from wine in the Gascogne region of southwest France. It is known as the world’s oldest brandy tracing its origin all the way to the 14th century. Of course, a spirit called RESISTANCE poked our interest.
The answer is two-fold. One cue is from the insect illustrated on the label. This is the microscopic but fearsome pest called grape phylloxera, latin name Daktulosphaira vitifoliae or Phylloxera vitifoliae (yes, its binomial name does change every now and then). Back in the 1860s, this hemipteran insect started attacking grapevines in Britain before reaching southeastern France where it caused severe damage in a major wine producing region. The phylloxera plague, as it was called, threatened to destroy entire vineyards. The industry was facing an unprecendented disaster. Desperate times call for desperate measures. Some farmers apparently resorted to burying live toads under the vines to “draw out the poison.”
The solution, as always, came from science. How plant breeders and entomologists dealt with phylloxera is a stirring tale of scientific triumph — a 19th century equivalent to the success of mRNA vaccines and genomic surveillance in driving the response to the COVID-19 pandemic. Given that phylloxera naturally occurs in North America, scientists hypothesized that native North American vines would be resistant unlike the European grapevine Vitis vinifera. This turned out to be true and paved the way to two creative technologies.
The first tech was grafting a Vitis vinifera scion onto a resistant North American rootstock, which works because phylloxera primarily attacks the roots. Grafting saved the day and the industry by enabling farmers to propagate traditional grapevine varieties on resistant North American rootstock of various Vitis species and their derivatives. One wonders where the European wine industry would be today without this technological intervention. Several scientists led the way. A key player was French botanist Jules Émile Planchon, who worked at Kew Gardens and collaborated closely with American scientists, building the sort of international research network we are used to today. Another is Gustave Foëx who developed a research vineyard on the campus of the École nationale d’agriculture de Montpellier, currently known as SupAgro. I visited this campus a few years ago and snapped a photo of a fascinating allegorical monument to grapevine grafting.
The second tech is hybridization or breeding European Vitis vinifera with various resistant stock of North American species. One of the key players was François Baco, a school teacher who moonlighted as a plant breeder and pioneered methods of Vitis hybridization. We owe to François Baco the famous hybrid Baco Blanc or Maurice Baco 22A, named after his deceased son. Baco 22A is resistant to phylloxera, and although it makes terrible wine, its high alcohol and low acidity make it perfect for distillation. Over the 20th century, Baco 22A became the most popular brandy variety in Southern France and was widely adopted by Armagnac producers. A success story and a cheaper alternative solution to grafting to deal with the phylloxera plague.
But that’s without counting on the odd politics of plant breeding. For reasons that seem to be rooted in romance rather than science, France’s Institut national de l’origine et de la qualité (INAO) decreed that Baco 22A cannot be used for Armagnac. It advised farmers to uproot all Baco 22A plants from their vineyards by 2010. They advised that Armagnac must be made of pure 100% Vitis vinifera grapes, even though various hybrids have been in use for over a century.
Armagnac producers fought back and managed to revert the harsh decree. Their arguments are as follows: “ i) Baco 22A was created in the region, by François Baco; ii) It was planted and adapted to the region; iii) It gives an originality to Armagnac; and iv) it offers additional quality.” I find it striking how they justify a pragmatic solution with some rather subjective romantic arguments.
Which takes us back to Jeff’s bottle of Bas Armagnac. RESISTANCE, as the label states, is made exclusively with Maurice Baco 22A grapes. Cyril Laudet, 8th generation wine maker of Chateau Laballe, named his “vibrant, next-gen Armagnac” RESISTANCE not just to highlight the phylloxera resistance of Baco 22A, but also to commemorate the stand that Armagnac producers took against INAO decree of uprooting Baco 22A from their vineyards. Vive La Résistance!
The modern politics of plant breeding
Many have argued that the modern polemics around the application of transgenics (GMO) and Gene Editing (GE) technologies to plant breeding are just an extension of this long-standing reluctance to accept new methods and approaches. As Noel Kingsbury reminds us in Hybrid — his monumental treatise of the history of plant breeding — plant breeding has always been fraught with politics, as in the fight for power and control.
But isn’t it funny how some fuss about the introduction of a single gene or mutation into a crop, but to save the wine industry, entire species and hybrids with their tens of thousands of genes have been introduced to European agriculture. Funny also how INAO fusses about the genetic purity of grapevines by rejecting widely grown inter-specific hybrids, but somehow tolerates grafting onto exotic species other than Vitis vinifera.
This is more politics than science. The arguments center around subjective and even romantic ideas that aren’t always rooted in facts. Perhaps it will take a crisis like the phylloxera plague to bring science to the forefront. And perhaps this crisis is just around the corner (see below).
There are also a lot of people out there trying to make a buck and con consumers with superficial populist arguments. Just watch Mondovino, the 2004 documentary about the wine industry, and make up your own mind. Spoiler alert: if you enjoy fancy wines and pay any attention to wine critics like Robert Parker, this will ruin it for you.
We face serious issues in agriculture. Climate change, global trade, population growth and a litany of issues are putting our agricultural production under unprecedented pressures. It’s time to adopt science and technology to address this global challenge.
The Ukraine war and the looming global food catastrophe
As I was writing this post, war broke up in Ukraine. In addition to the humanitarian and geopolitical upheaval, the war is expected to cause major disruptions to global food production and trade, not just because Ukraine and Russia are key food exporters, but also because these countries are major producer of the fertilizers that fuel crop production throughout the world. Already, there is an unprecedented spike in wheat prices as shown in @SergeZaka tweet.
Will this crisis impact the adoption of new plant breeding technologies? The future will tell.
I’m grateful to Jeff Ellis for alerting me to the RESISTANCE Armagnac and Ian Dry for sharing the pedigree of Baco 22A.