Putting high-tech breeding in more hands

New Agriculturist has a long report about marker-assisted selection and cowpea breeding. The gist of it is that cowpea is susceptible to Striga, or witchweed, a parasitic plant that can destroy the harvest totally. A resistance gene turned up in “an unimproved variety from Botswana”1 and is the basis of breeding programmes. Screening the results of crossing programmes conventionally is a nightmare, but a doddle if all you’re looking for is the presence of the resistance gene (or a marker close by). That, however, normally requires a well-equipped biotech lab. A UK charity, the Kirkhouse Trust, has been funding a consortium of cowpea breeders in west Africa with the specific aim of making marker-assisted selection available in the field.

The requirements for MAS boil down to a means of extracting DNA from the plant, and the equipment and reagents to then amplify the critical sequence in order to establish its presence or absence. The Trust’s priority has been to source reagents which do not require constant refrigeration and are not hazardous. DNA extraction has become a matter of squashing a leaf segment onto a specially treated paper, and the amplification reaction is provided in dry form, to which the user needs only to add water, and the DNA in the form of a small disc of paper.

One of the project’s six west African partners, in Burkina Faso, has made excellent progress and is now the focus of efforts and a training centre.

The key to the whole effort is the search for sustainability; the Trust believes that this is much more likely to be achieved by putting the technology directly into the hands of the practitioners, rather than by gifting it from on high. This way, the breeders themselves are more likely to have a stake in proving its worth and to be prepared to generate the internal pressure to incorporate MAS into their own national programmes over the long term.

I wonder, though, how many other valuable genes are hiding in unimproved varieties in Botswana and elsewhere. What about their sustainability?

  1. Where, bizarrely, Striga does not occur. Go figure. []

7 Replies to “Putting high-tech breeding in more hands”

  1. The Botswana landrace has the boring name of B-301. It was picked up on the basis of its field resistance to Alectra vogelii but then shown to be resistant to Striga populations from various parts of West Africa (see Annals of Applied Biology 1990 Vol. 116 No. 2 pp. 305-311). IITA got hold of this material and used it to breed IT97K-499-35, a line which has been heavily used as a parent for Striga resistance breeding throughout the region.

    The presence of unexpected resistances crops up all the time. A celebrated example is the gene for resistance to wheat eyespot disease, which was detected in a wild relative endemic to the Mediterranean basin, where the eyespot fungus does not exist.

    It does make one wonder, as Jeremy says, how many other things are hiding out there. It might be that it’s a mistake to take the rational view that suggest that it’s more likely that one will find a resistance gene among plant populations where the pathogen is present, or to find salinity tolerance in saline environments etc. But it’s hard to justify such irrationality when it comes to writing a grant proposal!

    1. I would call the “rational view”, a “reasonable hypothesis”. I think the support for it is not overwhelming and that, therefore, a random sample could be considered the most rational approach (best reflecting what we know), particularly if you stratify by geography (distance between samples and distance from the area of crop origin/highest diversity).

      Another weird case: tuber-less wild species Solanum etuberosum has been used to breed resistance to a tuber disease (scab?, I do not remember) in potato.

  2. I was interested by the mention of the “unimproved variety from Botswana” (I worked in Botswana in the ‘80s) so also did some sleuthing and found a reference (Euphytica 63, p85-93, behind a paywall) to “variety B301, a cowpea collected in Botswana by C. Riches…” Charlie was a weed scientist at the Botswana dept of agricultural research, now at NRI.

    1. Thanks Kate. Are you still in contact with Charlie? If so, would you consider asking him to write us a brief account of how he came to collect that variety?

  3. The Euphytica article referred to by Kate (Resistance of cowpea and cereals to the parasitic angiosperm Striga, by Lane and Bailey) was published in 1992. The Ann App Biol one that I mentioned was published 2 years earlier by Parker & Polniaszek. Curiously, all four authors came from the same institution, the now disbanded Long Ashton Research Station, near Bristol. Polniaszek, Parker and Charlie Riches jointly published a paper on Alectra resistance in cowpea in 1991 (Tropical Pest Management 1991 Vol. 37 No. 2 pp. 152-154).

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