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Effective communication on preserving crop diversity

This talk by Cary Fowler, on the Global Seed Vault at Svalbard, is worth watching both for the content and as a model for effective public speaking. For that reason, I've categorized it under "careers in science" as well as "agriculture." Note the lack of bullet-point slides!

[Note added 9/11: text slides can make presentations boring, but handouts of text slides help students focus on understanding rather than scribbling notes. So I'm going to cut down on text slides in talks at meetings, but not necessarily in guest lectures to undergraduate classes.]

It's worth noting that even dry, frozen seeds may lose viability in storage. (You could probably still recover DNA, but that's only of practical value for the few traits, if any, whose value can be identified from DNA sequence alone.) So it's good to take seeds out of storage and grow fresh seed periodically. Usually, you want to do this in a way that minimizes natural selection in the seed-increase environment, to avoid losing traits that were useful where the crop was grown originally. For example, you want plants far apart enough that tall plants don't shade shorter neighbors enough to keep them from producing seed. And you don't want plants that were particularly prolific in the seed-increase environment to be over-represented in your next stored sample. Preserving crop diversity is a vastly under-funded activity, although that is true of most areas of agricultural research without immediate links to short-term profit.

Although even a few stored seeds can be multiplied enough in a few years to deal with slowly developing problems, such as climate change, if there's a global wheat epidemic you need at least enough disease-resistant seed on hand that one cycle of seed multiplication will meet farmer needs for the next growing season.


It is worth emphasizing that the genebank Cary Fowler was talking about, in Svalbard, is a safety backup duplicate of seeds that are also stored in other genebanks. It is those other genebanks, the front line, if you like, that are responsible for maintaining the viability of the seeds. And you are right to point out the difficulties of doing that.

It will be interesting if the genebanks also deposit the regenerated samples at Svalbard. One could then accumulate a time series that might show how the genetic make-up of a variety changes over time.

I agree you do want to keep viable seed in storage, but I'll quibble that the only value of the DNA from non-viable seed is to allow retroactive examination of some traits. In the corporate plant breeding world the DNA fingerprint of a particular plant variety can have serious legal content (and thus consequences). So while a seed sample may no longer be viable to grow a plant, the DNA in the sample might still have its day in court.

The point about care and feeding of grow outs is spot on. One should also consider how many individual plants should be grown in a regeneration step - if the accession is not highly homozygous then there will be some loci with allele frequencies that might be low enough to be lost at random - even is care is taken to not shade shorter members, etc.

But finally I might make a plug for large scale industrial seed developers. If governments and NGOs are not going to put together the financial infrastructure to maintain significantly large seed quantities (re: Ford's point in his last paragraph) then perhaps the capitalist model of several significant entrepreneurial ventures competing for seed sales is one hope for getting around a global epidemic. Wheat actually makes a fine example - seed multiplication for wheat would naturally depend upon how much one has to start with, but beginning with say one kilogram of seed it will take many cycles to produce enough seedstock for the whole planet. Better perhaps to have in situ preservation of diversity such that relatively large quantities of seed are available to start.

I meant that you could extract DNA and use it to transform another plant, but it would be hard to identify useful genes without living plants to link DNA sequence to phenotype. I agree there could be other uses.

Commercial seed companies bear some responsibility for the genetic uniformity that led to the Southern Corn Leaf Blight epidemic, but (consistent with your point) they are also the ones who had enough resistant seed in storage and the infrastructure and initiative to arrange seed increase in the southern hemisphere, producing enough resistant seed for next year's northern hemisphere crop.

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