Super-rice defies triple whammy of stresses (Drought is no problem for super-rice)

For the first time, a single strain of genetically modified rice has been developed to handle drought, salty soils and lack of fertiliser. The aim is to “climate-proof” rice farms in Asia and Africa so that they can grow the same variety each year, regardless of the conditions.

Crops have previously been developed that cope with individual environmental stresses such as drought and salt, but this rice is the first to counter three at once.

“Considering the impact of climate instability on crop yields and food security, trait combinations such as our triple-stack technology will play a critical role in sustaining future generations,” says Eric Rey, president of Arcadia Biosciences in Davis, California, which developed the rice.

The salt-tolerance gene came from Arabidopsis thaliana, a type of cress widely used in plant research, and the drought-tolerance gene came from a common soil bacterium called Agrobacterium tumefaciens. The gene that enables the plant to use nitrogen more efficiently, so that it doesn’t need fertiliser, came from barley.

According to the International Rice Research Institute, drought affects 23 million hectares of rice in south and South-East Asia and costs $13 billion a year globally. In some states in India, it can reduce rice yields by 40 per cent. Salt is similarly problematic. According to the Food and Agriculture Organization of the United Nations, about 800 million hectares of land are affected by salt, costing agriculture an estimated $1 billion per year.

Passed the test

On 21 February, Arcadia announced it had completed two years of trials on the rice. The company compared the performance of its super rice with that of the unmodified parent rice in different environments.

Under a range of drought conditions, the yield of the modified rice was 12 to 17 per cent greater than that of the parent rice. With low levels of fertiliser, its yield was 13 to 18 per cent greater. When exposed to both of these stresses at once, the yield of the modified rice was 15 per cent more than that of the unmodified rice. Trials using a range of salty conditions showed the altered rice had a yield that was as much as 42 per cent more than the parent rice.

“This sounds very promising,” says Jonathan Jones of the Sainsbury Laboratory in Norwich, UK. “It is the first public claim I’ve heard of a stack of three different environmental tolerance traits, though I’m sure other companies are attempting something like it too.” Jones’s team recently developed and tested potatoes resistant to blight, the disease that caused the Irish potato famine.

“This looks good from the press release, but I’d like to see it pass peer review,” says Matthew Paul of Rothamsted Research in Harpenden, UK.

Arcadia is in the process of submitting its results to a peer-reviewed journal, says spokesman Ken Li.

Lots of genes

Arcadia is working to advance the technology in Asia and in Africa, collaborating with the African Agricultural Technology Foundation in Nairobi, Kenya. “In Africa, rice plants with some of these genes have completed initial trials already,” says Li. Arcadia is also developing wheat and maize with the climate-stress resistance genes.

Last year, drought-resistant maize became available in the US for the first time. Around 2000 farmers in the Corn Belt planted it on 50,000 hectares,according to the International Service for the Acquisition of Agri-Biotech Applications, a monitoring group funded by the biotechnology industry. The ISAAA also says the world’s first drought-resistant sugar cane is due for commercial release in Indonesia later this year.

Many genetically modified crops with “stacked” traits have been developed, says the ISAAA. But most are resistant to weedkiller, insects or diseases, rather than environmental stresses.