Category: Breeding

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Unbottling the lentil

ResearchBlogging.orgIt is well known that crops go through a genetic bottleneck at domestication. Due to the founder effect, they typically show a fraction of the genetic diversity found in their wild relatives. Which is bad, but fixable: fixing it is the plant breeder’s job — or part of it anyway. What’s less well known, according to a recent paper on lentils by Willy Erskine and co-authors in GRACE, is that the movement of a crop around the world can also often lead to bottlenecks. ((Erskine, W., Sarker, A., & Ashraf, M. (2010). Reconstructing an ancient bottleneck of the movement of the lentil (Lens culinaris ssp. culinaris) into South Asia Genetic Resources and Crop Evolution DOI: 10.1007/s10722-010-9582-4))

Lentil cultivation moved from Afghanistan into the Indo-Gangetic Plain sometime between 7000 and 4000 BC. The authors “reconstructed” this movement by growing random subsets of the ICARDA world lentil collection at two sites, Islamabad and Faisalabad, in Pakistan. Faisalabad is typical of conditions in the Plain, Islamabad is a transitional, mid-altitude environment.

They found that most Afghani accessions did not flower in Islamabad before the local material matured, due to a combination of temperature and photoperiod, the main determinants of flowering in lentils. The few that did were among the most late-flowering in the world. This is probably related to the shift in sowing from winter to spring as lentils moved from their area of origin in lowland SE Turkey and N Syria into the central Asian plateau. The data from Faisalabad in addition showed that every week’s delay in flowering resulted in a 9% loss of yield potential in the lowlands.

So there was strong selection for reduced sensitivity to photoperiod and a return to early flowering as the lentil moved into the Indo-Gangetic Plain, and consequently a genetic bottleneck. ((Incidentally, I am told by Jacob that a genetic bottleneck related to flowering time (earliness) also occurs in the Northern flint maize varieties in the US and Canada.)) But in a way the surprising thing is that there was no cork in the bottle. Where did the genetic variation that allowed adaptation to the Plain come from? The authors note that time to flower in lentils is controlled by both single gene and polygenic systems, and that early flowering is always recessive. Those recessive alleles for early flowering, which may have come from introgression from a wild relative in Afghanistan, must have occasionally come together and been selected for at mid-altitudes, which then “allowed selection for a radically earlier flowering habit as a new adaptive peak for the novel environment of the Indo-Gangetic Plain.”

The challenge is now for breeders to use these insights to broaden the genetic base of the crop in India, where lentil germplasm “is among the least variable among lentil-producing countries for agro-morphological traits … despite its vast area of cultivation there today.”

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Nibbles: FAOSTAT, Drought, Seeds, Helianthus, Coffee trade, CePaCT, Figs, Old rice and new pigeonpea, Navajo tea, Cattle diversity, Diabetes, Art, Aurochs, Cocks

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Nibbles: Climate change, Monitoring, Evaluation, Vegetables, FAO newsletters, Guardians

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Livestock genomes not enough

You may remember we nibbled a Science paper entitled Time to Tap Africa’s Livestock Genomes which got a lot of traction in the press a few weeks ago. It has also generated an interesting discussion at the DAD-Net forum, set off by the following contribution by Dr Ilse Köhler-Rollefson of the League for Pastoral Peoples and Endogenous Livestock Development, which she has kindly allowed us to reproduce here.

Congratulations on this article – it is certainly great to have these issues raised in a high profile scientific journal! However, after reading the summary about it presented in the BBC interview, I am a bit worried about the notion of the need to “tap Africa’s animal genetic resources” before they have become extinct. For one, they are already being “tapped” by African pastoralists — and have been tapped for hundreds or thousands of years — to enable survival in inhospitable areas. One crucial aspect of pastoralist livestock is the ability to walk for ever and thereby access and then ingest and metabolize vegetation that would otherwise be of no use to humans. Their contribution to food security is thus enormous. Unfortunately, to my knowledge, no scientific research has ever focused on “walkability.”

But what we urgently need to realise is that many of the wonderful characteristics of African and other pastoralist livestock are not a question of genetics, but of learned behaviour, as Saverio Kraetli has shown in his seminal studies of WoDaaBe cattle breeders in Niger. It is therefore a fallacy to believe that we can “fix” certain weaknesses of Western or high-performance breeds by introducing the genes of African livestock into them.

This does not make it less urgent to conserve pastoralist livestock, as food security for people in marginal areas remains a major concern. In their Biocultural Community Protocol, the Samburu have testified how replacement of the Red Massai sheep with Dorper has undermined their drought resistance.

African livestock breeds and their unique traits can only be conserved in living systems, using agroecosystem approaches as spelled out in one of the Strategic Priorities for Action of the Global Plan of Action for Animal Genetic Resources. Consequently we need enabling policies for livestock keepers, much more than additional research at the genome level — which would be unable to address complex traits such as walkability.

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Perennial grains gain credibility

ResearchBlogging.org It has been almost 10 days since the publication of Increased Food and Ecosystem Security via Perennial Grains in the Policy Forum of the journal Science. ((Glover, J., Reganold, J., Bell, L., Borevitz, J., Brummer, E., Buckler, E., Cox, C., Cox, T., Crews, T., Culman, S., DeHaan, L., Eriksson, D., Gill, B., Holland, J., Hu, F., Hulke, B., Ibrahim, A., Jackson, W., Jones, S., Murray, S., Paterson, A., Ploschuk, E., Sacks, E., Snapp, S., Tao, D., Van Tassel, D., Wade, L., Wyse, D., & Xu, Y. (2010). Increased Food and Ecosystem Security via Perennial Grains Science, 328 (5986), 1638-1639 DOI: 10.1126/science.1188761)) Not long in the 10,000 year history of agriculture, agreed, but long enough to have had a bit more impact, which it deserves for two reasons. First, there’s the subject itself: perennial grains. Then, there’s where it appeared; Science is pretty mainstream on most things, and its willingness to publish 29 authors from 21 institutions must help to bring perennial grains in from the cold.

As ever, the article is behind a paywall, so a summary is in order. Jerry Glover, of the Land institute in Salinas, Kansas, and his co-authors make several points. Grain yields from major crops have doubled since the 1950s, but 1 in 7 people are malnourished. Populations continue to grow, and biofuels are competing with food production. The best croplands are not at risk of soil erosion or degradation, but those lands are only 12.6% of total land area. More than half the world’s population depends instead on marginal lands, which are capable of growing crops but which are at risk of degradation under annual crops. Global food security depends on annual production of cereals, legumes and oilseeds, but for a variety of reasons the production of these staples is unsustainable and fragile. Against this background, as the authors say:

Development of perennial versions of important grain crops could expand options.

They go on to list the benefits of perennial crops, which I won’t repeat here, and some of the past history of this exciting research area. One of the key arguments against perennial crops is that plants make a trade-off between storing resources to overwinter vegetatively and putting those resources into seeds that can survive adverse conditions. In other words, you can have deep roots etc. or big seeds, but not both. But even if true, perennial grains may still be a good idea, for two reasons.

First, high yield is not the only factor governing the use of specific crops. Wheat, for example, yields less than maize, but is grown on a larger area than maize because it will produce some yield under conditions where most maize will produce none.

[L]ower yield perennial crops could be options where higher yield annuals cannot reliably achieve full yields. In semiarid regions of sub-Saharan Africa, annual crops often use less than 30% of rainfall due to high rates of water draining below root zones, evaporation and runoff … Perennial crops can reduce … water losses and be grown on highly erodable sites. For example perennial types of pigeon peas, important food crops and sources of biologically fixed nitrogen, are grown on steep slopes in regions of Malawi, China, and India.

The second reason perennial crops may be a good idea even though yields remain lower at present is that by virtue of their deeper roots and longer-lived leaf canopy, they can convert more sunlight into biomass than even the most advanced, most pampered annual crops. Miscanthus (a grass heavily touted for biofuel production) for example, with no additional fertilizer, produces almost 60% more aboveground biomass than heavily-fertilized maize.

Glover and his co-authors point out that plant breeders need to combine many desirable traits in perennial grains, and that new technologies like genome screening and marker-assisted selection can speed the process. They also point out that this requires greater investment, calling for new and expanded breeding programmes, expanded research, better global coordination, agreed prioritiy-setting and capacity development and training. ((Sound familiar?)) They also identify the many ways in which perennial crops could contribute to what they call “domestic and international challenges,” pointing out that several US agencies ought to have an interest in promoting R&D into perennial grains.

And that, perhaps, is where the article’s real importance lies, and why I am a little surprised that it has not (yet?) generated more discussion. With governments increasingly talking about food security in a much broader context than mere calories and proteins, and given Science’s clout as an outlet for important ideas, one can but hope that somewhere serious-minded people are considering shifting just a tiny bit of the agricultural research budget into obviously attractive alternatives to seeds and feeds.