Signs of hope for higher rice yields

IRIN Reuters AlertNet 17 Aug 10;

LOS BANOS, 17 August 2010 (IRIN) - Scientists at the International Rice Research Institute (IRRI) report signs of progress in their efforts to enhance rice's photosynthetic efficiency to boost yields.

If successful, global yields could rise by as much as 50 percent, avoiding potential rice shortages, or even future famines, specialists say.

According to IRRI, a global population increase of some two billion people by 2050 will require an extra 250 million metric tonnes of rice in Asia alone.

"Fifteen months into the project, things are looking positive," Paul Quick, principal scientist and head of IRRI's C4 rice project, told IRIN in Los Banos, the Philippines. "We have identified at least 10 to 15 plant phenotypes that look like the type of plant we are looking for, plants that are starting to show a switch to C4."

C4 plants - such as maize and sorghum - use a much more efficient photosynthesis process than rice (a C3 plant), produce a higher yield and use 1.5-3 times less water, he said.

With funding from the Bill and Melinda Gates Foundation, the first phase of the 15-year project is focusing on the discovery of the genes required for C4 photosynthesis.

"Achieving this goal will be extremely challenging as many of the processes that need to be changed are poorly understood at the genetic level," Quick said.

Plants typically have more than 30,000 genes so it is not easy to identify which genes are necessary to create the C4 engine. At the same time, thousands of plants need to be grown and screened for errors in their photosynthetic engine.

"It's like making a cake. We still don't know the recipe, but we now have a better idea of what the ingredients are," Jacqueline Dionora, a senior associate scientist for the project said.

New crop strains needed

According to the UN, food production needs to rise by 50 percent by the year 2030 to meet rising demand, fuelled by population growth, competition for water and increasing use of agricultural products for bio-fuels.

"Increased photosynthetic efficiency through the introduction of the C4 photosynthetic pathway is one mechanism by which this can be achieved," Quick said, citing its high light, water and nitrogen use efficiency.

"The C4-Rice project is seen as a high-risk scientific venture but this is nothing compared with the potential future risks to human health if food supply cannot meet demand."

A new study published by the Proceedings of the National Academy of Sciences (PNAS) [http://www.pnas.org/] - a peer-reviewed, scientific journal from the US - warned that rice production would be affected with rising temperatures due to climate change.

The study [http://www.pnas.org/content/early/2010/07/26/1001222107.full.pdf+html] by international scientists found evidence that the net impact of projected temperature increases would slow the growth of rice production in Asia. Rising temperatures during the past 25 years have already cut the yield growth rate by 10-20 percent in several areas.

About three billion people eat rice every day, and more than 60 percent of the world's one billion poorest and undernourished people who live in Asia depend on rice as their staple food, according to IRRI.

A decline in rice production would mean more people in poverty and hunger, the report's researchers warned.

"If we cannot change our rice production methods or develop new rice strains that can withstand higher temperatures, there will be a loss in rice production over the next few decades as days and nights get hotter," said Jarrod Welch, lead author of the report.

"This will get increasingly worse as temperatures rise further towards the middle of the century."

On 18 August, scientists will gather in Shanghai for the 15th international congress of photosynthesis research [http://www.picb.ac.cn/PS2010/index.html]. The three-day meeting will bring together experts from various disciplines of C4 biology, including biochemistry, evolution, genetic regulation, gene discovery, systems modelling and genetic engineering.