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?
- Where, bizarrely, Striga does not occur. Go figure. [↩]