Category: Breeding

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Cowpea B301’s back story

Via Kate Gold at RBG Kew comes Charlie Riches‘ account of how he found the Striga-resistant cowpea B301 and how it came to IITA.

Here is the story of B301 — serendipity perhaps but not such a random find as the previous blog entries suggest!

If we think about origin and diversity in cowpea there should be no surprise to find Striga gesnerioides resistance in a landrace from Botswana — B301 is not the only one. I collected the seed in 1981, if my memory serves from the field of a farmer called Batleng near of the village of Kopong just a few miles from the Agricultural Research Station at Sebele. 1 At that time I was starting on my quest for resistance to the root parasite Alectra vogelii. 2 My hypothesis was that resistance may be available among the many landraces grown by farmers on fields infested by A. vogelii. I had observed that while landraces often had few parasites, fields of the introduced cultivar Blackeye would be thick with A. vogelii. So as I travelled around the villages where I was doing various agronomic trials with farmers I looked out for cowpea landrace plants that had no parasite stems growing near to them or maybe just one among stands of cowpea where there were otherwise many emerged A. vogelii.

During the 1981 harvest I collected 30 or 40 accessions that eventually were contributed to the Botswana Cowpea collection — they were all characterised and listed in the Botswana Cowpea Catalogue produced by colleagues at Sebele. I think my copy is in the attic! My collections were a pod or two from single plants so initially I had to multiply seed. Then I did a pot trial with 66 exotic and local lines, including 39 of my single plant selections, growing the plants in A. vogelii infested soil. This indicated possible resistance; i.e, no parasite attachments could be found on the roots washed from pots, in B301, B319 and B359. I reported this finding and subsequent confirmation trials at the 4th International Symposium on Parasitic Flowering Plants in Marburg. (Riches C. 1987. The Identification of Resistance to Alectra vogelii in Cowpea. pages 701-708 of the Proceedings).

Subsequently I screened 358 local accessions and found a further 12 with no emerged parasite stems. I continued working with a number of landraces that supported no or very few A. vogelii. In the end B359 proved to be the best source of resistance in pots and the field — B301 did sometimes allow the odd parasite stem to develop.

Anyway to continue the story! While I was working in Botswana I was in contact with Chris Parker, who had been working on Striga for many years at the Weed Research Organisation [near Oxford in the UK] (closed down in 1986). He visited Botswana to discuss my work and it made sense to us to check out if my A. vogelii-resistant materials were also useful for S. gesnerioides. By this time Chris was working at Long Ashton Research Station (now also closed!) and with Tess Polniaszek demonstrated that B301 showed resistance to Striga populations from Burkina Faso, Cameroon, Niger and Mali — the first line to have this multi-strain resistance (Parker, C. and Polniaszek, T.I. 1990. Parasitism of cowpea by Striga gesnerioides: variation in virulence and discovery of a new source of host resistance. Annals of Applied Biology, 116: 305-311). I provided all my Botswana accessions to B.B. Singh at IITA and the rest is history.

B301 is not the only line to provide dual parasite resistance in West Africa; there are now a number of others e.g. IT81D 849. Because there are a number of strains of A. vogelii, cowpea lines that are resistant in West Africa are not always so in East and Southern Africa. There is currently a group working in Malawi and Tanzania, funded by Collaborative Crop Research Program of the McKnight Foundation, that is developing resistant lines for southern Africa. B301 is being used as one parent in a back-cross breeding program. So after nearly 30 years the genes are on their way home!

What this story shows is the importance of collaboration and for researchers to share their findings.

Returning to the original comments in the blog I do not think it curious at all that resistance to S. gesnerioides can be found in Botswana where this species is very common but does not parasitise cowpea. As migrations and trade took cowpea across the continent from West Africa some landraces will probably have been taken from areas of West Africa infested by S. gesnerioides. 3

A more interesting question is why strains of Striga that are capable of attacking cowpea have not been disseminated from West to East and Southern Africa on cowpea seed! In these regions there are a number of distinct, host specific, morphotypic variants mainly on wild legumes and occasionally tobacco but never cowpea (see Ralston, Riches & Musselman, 1997. Morphology and hosts of three Striga species in Botswana. Adansonia 2, 195-215). 4

Thanks so much to Charles Riches for this account. Gotta love the interwebs.

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Is it a bird? Is it a plane? It’s Super Rice.

Cutting through the hype, there may be some substance in the announcement by the University of Arizona that it is leading a team funded to the tune of USD 9.9 million “to develop ‘super rice’“. 5 The plan is to understand the genomes of all 24 rice species, the better to breed the two species — Oryza sativa and O. glaberrima — that yield the rice crop.

The announcement contains a lot of information about how this effort will help researchers to understand the evolutionary history and current functioning of rice. But there’s also a food security angle, natch.

“During the domestication process, people end up selecting a couple of plants and crossing them,” [said University of Arizona plant scientist Rod] Wing. “This way, one of them became the founder of all the domesticated plants. That variety was then improved over thousands of years, but it contains only a very small variety of genes that could be used for crop improvement.” … This so-called domestication bottleneck leads to crop plants with highly desirable traits such as high yield but deficiencies in other areas such as compromised ability to fight off diseases or cope with droughts.

I expect the researchers might be wondering whether they can duplicate the domestication events that resulted in modern rice, as wheat researchers did in constructing synthetic bread wheats, injecting a whole lot more agricultural biodiversity into the crop.

And here’s a cool idea; spend some of the loot on public awareness:

As an outreach component, the project will include a biannual Plant Science Family Night program at Ventana Vista Elementary School in Tucson, targeting K-5 students and families, with the goal of getting children and their families in the greater Tucson area excited about plants and the role plant science plays in ensuring a safe, sustainable and secure food supply for our planet.

Shouldn’t every big grant do something similar?

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Nibbles: Cattle nutrition, Maize, Freshwater biota, Modeling maize, Rice, Book, Veg, Urban ag

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Is there really no downside to Brazil’s agricultural miracle?

It’s not easy to explain the Brazilian agricultural miracle to a lay audience in a couple of magazine pages, and The Economist makes a pretty good fist of it. It points out that the astonishing increase in crop and meat production in Brazil in the past ten to fifteen year — and it is astonishing, more that 300% by value — has come about due to an expansion in the amount of land under the plow, sure, but much more so due to an increase in productivity. It rightly heaps praise on Embrapa, Brazil’s agricultural research corporation, for devising a system that has made the cerrado, Brazil’s hitherto agronomically intractable savannah, so productive. It highlights the fact that a key part of that system is improved germplasm — of Brachiaria, soybean, zebu cattle — originally from other parts of the world, incidentally helping make the case for international interdependence in genetic resources. 6 And much more.

What it resolutely does not do is give any sense of the cost of all this. I don’t mean the monetary cost, though it would have been nice for policy makers to be reminded that agricultural research does cost money, though the potential returns are great. The graph shows what’s been happening to Embrapa’s budget of late. A billion reais of agricultural research in 2006 bought 108 billion reais of crop production.

But I was really thinking of environmental and social costs. The Economist article says that Brazil is “often accused of levelling the rainforest to create its farms, but hardly any of this new land lies in Amazonia; most is cerrado.” So that’s all right then. No problem at all if 50% of one of the world’s biodiversity hotspots has been destroyed. 7 After all, it’s not the Amazon. A truly comprehensive overview of Brazil’s undoubted agricultural successes would surely cast at least a cursory look at the downside, if only to say that it’s all been worth it. Especially since plans are afoot to export the system to the African savannah. And it’s not as if the information is not out there.

A final observation. One key point the article makes is that the success of the agricultural development model used in the cerrado is that farms are big.

Like almost every large farming country, Brazil is divided between productive giant operations and inefficient hobby farms.

Well, leave aside for a moment whether it is empirically true that big means efficient and small inefficient in farming. Leave aside also the issue of with regard to what efficiency is being measured, and whether that makes any sense. Leave all that aside. I would not be surprised if millions of subsistence farming families around the world were to concede that what they did was not particularly efficient. But I think they would find it astonishing — and not a little insulting — to see their daily struggles described as a hobby.