Breeders not so bad after all

by Luigi Guarino on January 12, 2010

ResearchBlogging.orgSpeaking of evil plant breeders:

It is generally thought that continuous selection among crosses of genetically related cultivars has led to a narrowing of the genetic base of the crops on which modern agriculture is based, contributing to the genetic erosion of the crop gene pools on which breeding is based.

But this may be another faulty meta-narrative. At least that’s what a group of researchers from the Dutch genebank say, as a result of a meta-analysis of 44 genetic diversity studies of the varieties of 8 crops released in successive decades.1 This is the result:

trend

The meta analysis demonstrated that overall in the long run no substantial reduction in the regional diversity of crop varieties released by plant breeders has taken place.

Of course, that says nothing about the relative frequency at which these varieties have been grown by farmers, also an important aspect of overall diversity, along with how different the varieties are. Anyway, that decrease in the 60’s was only about 6%, and that has been reversed since then. How? Because of genebanks, say the authors.

In the 1960s and 1970s the introduction of the new Green Revolution-type cultivars for the major staple crops led to concerns on the disappearance of the world’s varietal wealth of crop plants. The widely shared concerns ultimately resulted in the establishment of a worldwide network of international genebanks hosted by the CGIAR research centres. The seed samples stored in these genebanks facilitated access of the world’s crop diversity to plant breeders world wide. It seems likely that the easy access to crop diversity provided by the genebanks, improved communication among breeders and easier exchange of seeds were factors contributing to the reversal of the initial trend in diversity reduction as observed in this meta analysis. Also the increased use of crop wild relatives for breeding and in recent years the use of synthetic wheats will have contributed to the observed diversity increase.

Well, it will be interesting to see, in due course, whether the restrictions on access which followed the Convention on Biological Diversity, had an effect, and whether the International Treaty on PGRFA eventually set the world to rights. As it was designed to do.

Footnotes:
  1. Wouw, M., Hintum, T., Kik, C., Treuren, R., & Visser, B. (2010). Genetic diversity trends in twentieth century crop cultivars: a meta analysis Theoretical and Applied Genetics DOI: 10.1007/s00122-009-1252-6 []

{ 4 comments… read them below or add one }

André January 13, 2010 at 4:56 pm

This is a very interesting analysis, but one must be careful with the conclusions one might wish to draw from it. There was, as the authors say, in agreement with authors of the background studies, “no substantial reduction in the regional diversity of crop varieties”, but surely the nature of the diversity has changed and a number of alleles (‘genes’ in common parlance) have been ‘lost’ in the process. This is no doubt a good thing in relation to ‘bad genes’.

Unfortunately, the statistics will not convince those who believe in diversity loss, as a matter of faith or more trivially of convenience as a support for their cause or business. Nor will they necessarily prevail over anecdotal evidence of disappearances from the countryside or the marketplace.

I have put ‘lost’ between quotes above. Of course, a gene is only lost when has completely disappeared or is no longer readily available. Hence the need for a locally-rooted vibrant and diversified breeding industry (breeders maintain germplasm collections…) and for an extensive and well-endowed genebanks network.

By the way, Le Clerc et al. (2006) provide an interesting histogramme of the distribution of scores for ‘time of anthesis’, by decade. Any interest in looking at this from the point of view of climate change?

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Luigi January 13, 2010 at 8:28 pm

Interesting. Do you have a pdf?

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Monkey January 14, 2010 at 9:52 am

Genebanks from the plant breeders in developed countries where biodiversity is gone long ago. This research focuses on the past but how about the future? Protect biodiversity by aiding low scale farmers in developed countries with the most sustainable and productive crops, not by charging royalties which will only lead to the ‘erosion’ of REAL diversity and not STORED one.

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Ewan R January 14, 2010 at 3:44 pm

By “most sustainable and productive” crops do you mean those which are already used, or do you suggest a switch to sustainable productive crops – there is absolutely no reason why sustainable productive crops do not include those for which royalties are charged. Indeed as far as I am aware, most hybrids (most productive) are protected by exactly the same kind of ‘don’t save seed’ laws as are transgenic plants (which depending on the system utilized are arguably more sustainable than non-transgenic hybrids, and likely to become more-so in coming yeears).

In terms of biodiversity the role agriculture has to play is varied – is it important to have as much variety in the field as possible (thus probably reducing yields, and therefore increasing agricultures footprint to meet yield demands) or should agriculture strive to produce as much as is possible in as small a footprint as possible thus conserving biodiversity outside of the field (a recent(ish) paper in science seemed to suggest that biodiversity falls off massively when land is farmed under even very lax farming, with only a minor difference between lax and intensive farming, such that it is likely the case that for a given amount of yield it is preferable to utilize intensive farming on the smaller amount of land leading to more land available which isnt actively being farmed where biodiversity will be much higher than under either farming system.

The role that seedbanks etc play in this system is important in maintaining a diverse range of germplasms available to generate hybrids from – frankly I dont see that any crop species should really be heralded as a great thing in terms of biodiversity other than in the role it may play in agriculture – as even historically agriculture is the biggest kick in the teeth to biodiversity you can get – far better to have non-ag species out in the real world providing biodiversity while storing the biodiversity of crop species against future need.

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