50 years of cassava diversity: what went into the bank, and what came out

Two new papers in Plants, published two months apart, tell the story of CIAT’s cassava genebank 1 from opposite ends: how the collection was assembled and conserved, and what breeders have actually done with it. Read together, they amount to a remarkably candid 50-year audit of a slow-motion agricultural asset. I’ll just give you the main beats here. It’s really worth reading both papers in full.

Part I is the origin story. Botanist Victor Manuel Patiño’s 1969–70 expeditions alone brought in roughly a third of today’s 5,000 or so cassava landraces, transported as stem cuttings across Colombia, Ecuador, Venezuela and beyond, often in difficult conditions and under changing quarantine rules.

The collection has its blind spots: Brazil and the Guianas remain poorly represented 2, passport information can be patchy, and the overwhelmingly male composition of historical collecting teams probably meant that some of the varietal knowledge held by women farmers went unrecorded.

Conservation itself has been a moving target. It has evolved from field genebanks to in vitro slow-growth tissue culture storage after a frogskin-disease scare forced the field collection to close in 2003, and now cryopreservation at CIAT’s Future Seeds facility. Meanwhile, DNA fingerprinting keeps revealing an awkward truth familiar to genebank curators everywhere: the names people give varieties and the genetic identities of the material do not always agree. A lot of effort over the years has also gone into testing for pathogens to ensure that distribution is safe.

Part II asks what all this diversity is actually for? The answer has also changed considerably over five decades. Early researchers chased traits such as high protein and low cyanogenic content before turning towards yield and starch percentage in the Green Revolution era.

The payoffs have been considerable: landraces have contributed traits such as resistance to pests and diseases, adaptation to acid soils and highland cold, and quality traits for fresh-market cooking versus industrial starch. The route from accession to released variety is rarely direct: a landrace gets screened for a trait, crossed, then recombined and selected over several more generations before anything reaches a farmer’s field. The results include varieties like Nataima-3, bred for whitefly resistance thanks to an Ecuadorian landrace. At the same time, the authors argue that cassava breeding now needs to move beyond broad phenotypic selection towards more systematic use of inbred lines, because the crop’s high heterozygosity makes the introduction of specific traits particularly difficult.

The two papers therefore tell a big story about genebanks. Collecting diversity is only the beginning; its value is realized decades later, when a breeder encounters a problem that nobody could have anticipated when the stuff was first collected. The cassava collection is a long-term portfolio of biological options, one whose contents have taken half a century to assemble, whose inventory is still being corrected, and whose most valuable assets may be the ones that have not yet been used.

A new project is looking to genetically engineer cassava to photosynthesize more efficiently at higher temperatures. I do wonder whether someone has already checked whether any of those 5,000 landraces might help with that. Maybe they can’t, but it’s worth having a look. And you never know, something else of interest might jump out. That’s the beauty of large international collections of crop diversity such as CIAT’s.

Brainfood: Mung bean pan-genome, Sunflower resistance, Olive adaptation, Allergic peanuts, Weird coffees, Chinese tea, Measuring selection

Nibbles: Processing, Shōjin Ryōri, Philippines landraces, National Soybean Germplasm Collection, Kazakhstan genebank, Reading chocolate, Parmesan bank

  1. Grinding, fermenting, and detoxifying our way to bigger brains — an anthropologist makes the case that food processing, historically women’s work, did as much for human evolution as the mammoth-spearing got credit for.
  2. Speaking of transforming raw ingredients into something civilization-defining: a Japanese temple has been quietly perfecting vegan cooking for 700 years, no marketing department required.
  3. Meanwhile in the Philippines, Naturland, the international association for organic farming from Germany, is linking up with Global Seed Savers Philippines, to help farmers get their hands on indigenous crop diversity before it disappears.
  4. If you want to see what “future-proofing seeds” looks like at scale, the National Soybean Germplasm Collection just turned 100: a century of squirreling away soybean diversity, just in case.
  5. Kazakhstan wants in on the squirreling too: plans are moving forward for a new genebank to safeguard agricultural biodiversity across Islamic Organization for Food Security member states.
  6. The University of Reading is also 100, and in celebration scientists there harvested beans from its cacao collection (yes, it has a cacao collection) to make Britain’s first homegrown chocolate bar since 1932, a novelty act with a serious undertone: climate change is squeezing cacao’s traditional growing belt.
  7. And in Italy, the squeeze is already showing up on the balance sheet: Parmesan’s “Fort Knox” — $350 million of cheese squirreled away as loan collateral — is feeling the heat, with rising cooling costs and falling yields rattling wine and olive oil too.

Nibbles: Festivals, Wheat breeding, Cowpea, Community seed bank, Mint diversity

  1. Festivals, rituals and seed-saving go hand in hand, as this photo essay on Koraput’s Adivasis shows for World Indigenous Peoples Day.
  2. Speaking of unlikely alliances, Israeli and Palestinian researchers have teamed up on wheat that can take the heat in a warming, drying Middle East.
  3. Not to be outdone in the resilience stakes, the cowpea shrugs off both drought and flooding, according to FAO.
  4. If all this talk of resilient crops has you inspired, here’s a how-to on starting your own community seed bank, in South Africa or anywhere else for that matter.
  5. And for when preservation is really about nostalgia: Romania’s Buzau genebank is keeping childhood mint flavours alive, chocolate, clove and vanilla notes included.

Nibbles: Museum of Cider, Aport apple, Rattan genebank, Sri Lanka rice, Saudi coffee landscapes

  1. In the UK, Herefordshire’s Museum of Cider is picking up national recognition for its genebank of heritage apple trees. The BBC’s canonical autumnal apple story comes a little early this year.
  2. Speaking of iconic apples, Kazakhstan is scaling up efforts to bring back the Aport, the giant heirloom that once made Almaty famous. No word of museums, though. Or cider.
  3. Over in the Philippines, Department of Environment and Natural Resources is beefing up its rattan genebank to keep pace with demand, with forest stewards in Bukidnon planting seedlings to match. Furniture makers need genebanks as much as cider makers.
  4. Sri Lanka’s pre-Green Revolution heirloom rice varieties, purana haal, are being eyed for their resilience and disease-management potential. Good thing they’re in the national genebank.
  5. Saudi Arabia’s Jazan terraced coffee farms are turning into rural and ecotourism hotspots, proving not all agrobiodiversity needs to be in a genebank to survive. But it helps.