Category: Genebanks

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The error of genebanks’ ways

ResearchBlogging.orgThe Crop Science paper by Mark van de Wouw, Rob van Treurena and Theo van Hintum ((Wouw, M., Treuren, R., & Hintum, T. (2011). Authenticity of Old Cultivars in Genebank Collections: A Case Study on Lettuce Crop Science, 51 (2) DOI: 10.2135/cropsci2010.09.0511)) of the Centre for
Genetic Resources, the Netherlands (CGN) probably deserves more than the rather cryptic Nibble we gave it yesterday. It certainly seems to be eliciting some interest in the media.

What van de Wouw and friends did was look in detail at alleged duplicates in a collection, the Dutch collection of old lettuce cultivars to be precise. I say alleged because when the researchers DNA fingerprinted plants from accessions which by all rights should have been identical, they weren’t. Known duplicates turned out to be unknown something elses. About 20% of accessions with the same cultivar name (out of a total of 283 accessions in 124 name groups) were in fact significantly different at the DNA level, and they shouldn’t have been. So, for example, 3 of the 12 accessions labelled Maikönig (or similar) in the collection are probably no such thing:

Lettuce is inbreeding, and “[d]iversity within accessions and accidental crossing is not a major issue for cultivars of a self-pollinating crop…” The researchers therefore blame “mislabeling and seed contaminations during processing and handling of the accessions,” mostly “from the period before uptake in the CGN collection.” Better procedures and better documentation systems now exist, and similar problems are much less likely, at least in properly run genebanks.

But what to do with the existing errors? Just remove the erroneous name from the database? Or get rid of the seeds too?

Removing the seeds might be the preferred option, as maintaining a collection is a costly operation and funds are limited… However, if the nonauthentic accession has been extensively evaluated and shown to have valuable characteristics it might be worthwhile to keep the accession, without the cultivar name, in the collection, provided it is confirmed that the accession was already nonauthentic at the time the evaluations were performed. Alternatively, a seed sample could be reacquired in case authentic material is still available elsewhere.

Was it all worth it? Does the significance of this study go beyond the fact that some accessions of old lettuce cultivars in the Dutch genebank may have got mixed up in the past? Well, there are 7.4 million odd accessions in the world’s genebanks, but they’re not all different. Some have no duplicates at all, others dozens. Maybe only about 2 million are unique. That adds to costs, so it would be worthwhile getting rid of a few duplicates. But only if they are in fact truly duplicates, and can easily be identified as such. As the cost of genotyping declines, detecting duplicates (at least in inbreeders and vegetatively propagated species) is becoming cheaper than maintaining them. That may be the most important message to take home from this thought-provoking paper.

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The Economist mentions crop wild relatives!

The Economist’s special feature on feeding the world pretty much pushed all the expected buttons. The challenges are great: food supplies probably have to increase by 70% in the next 40 years. More inputs — land, irrigation, fertilizers — is not exactly off the table as a strategy, but won’t be nearly enough. Technology is what we need: in particular plant breeding, though also intensification of livestock keeping. It won’t be easy: that 70% increase in production translates into things like a doubling of the growth rates in yields of wheat, to >2% per year. And climate change will make what would have been a difficult task at the best of times even harder. The growth rate in wheat yield will have to be achieved in the face of a likely 20% fall caused by a 2ºC increase in global temperatures. But advances in genomics make all this possible, although the way this was presented was somewhat eccentric, I thought:

…the change likely to generate the biggest yield gains in the food business—perhaps 1.5-2% a year—is the development of “marker-assisted breeding”—in other words, genetic marking and selection in plants, which includes genetically modifying them but also involves a range of other techniques.

Also predictable was the trotting out of the dreaded 75% figure for loss of agrobiodiversity:

Three-quarters of all the world’s plant genetic material may have gone already, mostly by habitat destruction, says Pasquale Steduto of the FAO, and more is going every day.

What was less expected, at least to me, was a final, brief but nevertheless welcome, section on the importance of micronutrients, which even suggested that technology might not be sufficient on its own:

Better nutrition, in short, is not a matter of handing out diet sheets and expecting everyone to eat happily ever after. Rather, you have to try a range of things: education; supplements; fortifying processed foods with extra vitamins; breeding crops with extra nutrients in them. But the nutrients have to be in things people want to eat.

Most unexpected, however, and most welcome, were the couple of references crop wild relatives as possible sources for solutions:

…hundreds of thousands of older varieties and wild relatives are left to the vagaries of land-use change, global warming and chance. This is a worry because some of the most desirable characteristics of plants—taste, drought- and pest-resistance—originally came from the wild gene pool, which will be needed again one day.

Alas, no mention of genebanks there, you’ll notice. Which I suppose one comes to expect. Didn’t anyone at CIMMYT, IRRI or ILRI — who all get nice name-checks — mention to the writer that in fact hundreds of thousands of samples of landraces and wild relatives are (relatively) safe in genebanks, not least in those very institutes? And that these genebanks need support, and should not be taken for granted?

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