AgroPages-Bangladeshi wild variety rekindles hope for breakthrough in global rice yield boost-Agricultural news

Bangladeshi scientist Md Sazzadur Rahman at IRRI’s C4 Rice Project research facility in Los Banos, the Philippines Dhaka Tribune

For the past 11 years, scientists have been trying to convert paddy into a photosynthesis-efficient plant, which would produce up to 50% more grains using the sunlight, without requiring more land and water.

The idea came from the concern that the traditional research, which results in just 1% rise in the yearly yield, would not be enough to meet the ever-growing demand.

The plan was to engineer paddy in a way that its leaf anatomy permits greater efficiency in photosynthesis thereby, dramatically boosting the yields in one of the world’s most consumed cereal.

Now a wild rice – Uri dhan (Porteresia coarctata) – that grows in saline estuaries of Bangladesh rekindled hope for a possible breakthrough in changing rice plant architecture.

Bangladeshi scientists have found elements of greater photosynthesis efficiency in Uri dhan.

Scientists at the International Rice Research Institute (IRRI) in the Philippines, who are working in tandem with researchers drawn from 12 institutions in eight countries on a 20-year ‘C4 Rice Project’ are now seeking to take the Uri dhan samples to Los Banos, the IRRI headquarters, for a fusion.

“We’re working out an MTA (material transfer agreement) to receive Uri dhan samples from Bangladesh,” Principal Scientist and Head of the C4 Rice Project, William Paul Quick told the Dhaka Tribune during this writer’s recent visit to the IRRI.

An MTA is a contract that governs the transfer of tangible research materials between two organizations, when the recipient intends to use it for research purposes.

Prof Zeba Islam Seraj, who teaches biochemistry and molecular biology at the University of Dhaka and has a long experience of salt-tolerant rice breeding employing Uri dhan, told the Dhaka Tribune that her lab is ready to provide the IRRI with the material.

During photosynthesis, plants take carbon dioxide, water, and light, and turn them into sugar and oxygen. The sugar is then used by the plants for food, and the oxygen is released into the atmosphere.

Rice uses the C3 photosynthetic pathway, which in hot and dry environments is much less efficient than the C4 pathway used by other plants such as maize, sugarcane and sorghum. Scientists thought that if rice could "switch" to use C4 photosynthesis, its productivity would increase by 50 percent.

Prof Zeba Islam Seraj explained, "Maize, sorghum and sugarcane are C4 photo-synthesisers, while rice is C3. The C4 photo-synthesisers are more efficient in energy uptake." She said C4 plants such as maize and sorghum are more efficient at carbon assimilation than C3 species, and in addition they display greater water use efficiency, better nitrogen use efficiency and higher-temperature tolerance.

The C4 Rice Project, often dubbed as "grand challenge" of the 21st century, is an international collaboration between 18 research groups, from 12 institutions in eight countries. The institutions are: Australian National University (Australia), University of Toronto (Canada), Chinese Academy of Sciences (China), Max Planck Institute of Molecular Plant Physiology and Heinrich Heine University (Germany), International Rice Research Institute(the Philippines), Academia Sinica Institute of Molecular Biology (Taipei), University of Cambridge and University of Oxford (UK), Donald Danforth Center, Washington State University, and University of Minnesota (USA).

Over three billion people, including 160 million in Bangladesh, depend on rice for survival, and owing to predicted population increases and a general trend towards urbanisation, land that provided enough rice to feed 27 people in 2010 will need to support 43 by 2050.

Talking to the Dhaka Tribune, William Paul Quick said, “Its well over 10 years now and we’re still studying how to regulate the leaf anatomy (to make rice plant more efficient photo- synthesizer). Zeba is working (on Uri dhan) in Bangladesh. We’re looking forward to acquire the material.”

Dr Paul Quick, also a plant physiology professor of the University of Sheffield, UK, said his team, where two Bangladeshi rice scientists (Md Sazzadur Rahman and Dr Hisam Al Rabbi) are also working now, has been screening as many as 4,500 rice accessions for this photosynthesis trait.

“We’ve established joint lab in China and works are going on in different locations,” said Dr Paul Quick adding that in the process they’ve applied gene editing techniques and ended up getting some water-efficient rice lines.

“If successes come our way we’ll have rice varieties in the future requiring half the water they do require now. We’re now examining the advanced lines to see whether there is ‘yield penalty’ – meaning whether we’re getting less grains.”

The C4 Rice Project was first conceived by John Sheehy, a plant physiologist who was the head of the Applied Photosynthesis Group at the IRRI from 1995 to 2009. The costs of the project were estimated to be about $5m per year. In October 2008, the Bill & Melinda Gates Foundation awarded IRRI a grant of $11.1 million to begin the research. Currently the project is into its phase-III (2015-2019).

Experts noted that successful completion of engineering rice into a C4 plant would be a "game-changer" since the '60s of last century when scientists had first developed semi-dwarf rice varieties heralding the famous "Green Revolution".