A Tale of Two Plants

The first is about  genetic engineering, but it is about improving the survival rates and nutritional value of a plant that as many as 500,000,000 depend upon. It is NOT about kill genes, pesticides, and profit.

Manioc – probably better known as cassava (Manihot esculenta) in Europe – is native to South America, but is extensively cultivated as an annual crop in tropical and subtropical regions for its edible starchy, tuberous root, a major source of carbohydrates.

Manihot esculenta

It is a staple for 250,000,000 dwellers of sub-Sahara Africa, but the genetic diversity varies throughout the African region with greater diversity in the south and less towards the north. Surprisingly, this diversity is related to marriage customs.

The authors collected and genotyped varieties of manioc grown in each village, and found that the genetic diversity of manioc clustered into distinct geographic regions, with the greatest diversity found in the southern part of the country, and the lowest diversity in the north. The authors suggest that regional differences in manioc diversity may reflect in part the different marital practices in the two regions: In the south, a new bride moves to her husband’s village and brings along manioc varieties from her mother’s farm, whereas in the north, new brides move empty-handed and receive manioc varieties from their mothers-in-law. The result, the authors suggest, is that the inflow of women in the north is not accompanied by an inflow of new varieties of manioc. According to the authors, understanding the relationship between marriage exchanges and seed exchanges may help decipher geographical patterns of crop diversity.

The original study is here.

Cassava is primarily a source of carbohydrates and provides only 30% of protein requirements. It also contains substances that release poisonous hydrogen cyanide. Now the geneticists got involved.

Narayanan Narayanan et al. at the Donald Danforth Plant Science Center (St. Louis, USA) have delivered a ‘double-whammy’ to cassava research, which not only reduces cyanogen content, but also increases protein levels. Using a GM approach they created plants that over-express hydroxynitrile lyase (HNL), which accelerates production and hence also loss of HCN during food processing, and – because the HNL is located in the cell walls, which survive the processing – leads to an increase in protein content of the foodstuff!

In addition,

Nearly US$12 million – from the Bill & Melinda Gates Foundation, The Monsanto Fund and the Howard Buffett Foundation – has been provided to VIRCA (the Virus Resistant Cassava for Africa project). The hope is to generate cassava resistant to such viruses as CBSD (cassava brown streak disease) and CMD (cassava mosaic disease), which are causing major, devastating losses to cassava crops in Uganda and Kenya; indeed, CBSD is listed as one of the seven most dangerous plant diseases in the world for the impact it can have on food and economic security across Africa. And news that will be boosted by the announcement that BGI (formerly the Beijing Genomics Institute) will ‘work with Colombia’s International Center for Tropical Agriculture (CIAT) to sequence 5,000 cassava genotypes in a project that will aid scientists as they improve the crop through genetic engineering’.

Unfortunately, many countries have banned the production of genetically modified crops, including those such as Brazil, Paraguay, and Peru, countries that have a combined production of 25million tons. This knee-jerk reaction to the well-publicized predatory business practices of industry giants such as Monsanto, will impact the ability of these nations to feed their people, just as demands on agriculture are increasing.

The other plant in the scientific news is wheat.

Triticum durum

Plant scientists on Sunday said they had bred a strain of wheat that thrives in saline soils, boosting the quest to feed Earth’s growing population at a time of water stress and climate change.

Durum wheat with a salt-loving gene had yields which were up to 25 percent greater than ordinary counterparts, according to trials carried out in highly saline fields.

The gene, called TmHKT1;5-A, helps remove sodium from water that is transported from the plant’s roots to the leaves, said a research team led by Matthew Gilliham of the University of Adelaide, southern Australia.

Spotted in a scan of ancestral wheat strains, TmHKT1;5-A was inserted into a commercial strain by traditional cross-breeding, not through genetic engineering, which is contested in many countries.

Durum wheat – Latin name Triticum turgidum – is used for making pasta, bulgur and couscous. It is more salt-sensitive than bread wheat (Triticum aestivum).

By some estimates, world food requirements will soar by 70 percent by 2050 as the planet’s population rises from seven billion today to nine billion.

Salinity is a growing issue in many arid and semi-arid regions where irrigation exacerbates the already salty soils.

Publication of the study in the journal Nature Biotechnology coincided with the eve of the World Water Forum, in Marseille, France, where water scarcity and agricultural needs for water will be major issues.

In January, scientists in Britain and Japan unveiled a fast-track way to spot promising genes and splice them, using classical methods, into rice plants to make them salt-tolerant.

The first beneficiaries of this could be Japanese farmers whose fields were submerged by last year’s tsunami.

Around 20,000 hectares (50,000 acres) of paddy fields in northeastern Japan were flooded by seawater, wrecking their ability to produce crops with conventional rice cultivars.

A combination of traditional and transgenic gene manipulation is the future of feeding the world.

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