Friday, October 11, 2013

Flood-tolerant rice: The future of agriculture

With sea levels rising and weather conditions worsening, plant scientists continue to search for ways to save agricultural plants from environmental threats to sustain the world's food supply.
Countries are in need of rice varieties that can "tolerate higher temperature and drought, survive prolonged flooding, and soil salinity," said Dr. Robert S. Zeigler, Director General, International Rice Research Institute (IRRI) during the 11th International Society for Plant Anaerobiosis (ISPA) International Conference, Monday.
Rice shortage is one of the threats the scientists of IRRI are trying to prevent from coming to pass.
Being the primary staple food of 70% of the world's poor, the demand for rice increases with each generation. Even with the world's temperature increase, changes in rainfall, and weather disasters, we would still need to make 100 million more tons of rice every 12 years, Zeigler said.
Rice is also grown in monsoonal areas are prone to flooding.
"But everything we need, nature has already figured out," said Professor Rens Voesenek, President of the ISPA. "It's only a matter of looking for the genes responsible for desirable traits that need to be interbred within the species of plants."
"We have to explore nature to find those genes which are relevant to help us make more tolerant crops. Nature discovered this all very many, many times," he added.
"There are many plants close to rivers, and many plants in marshes, and in swamps throughout the world. So there are genes, there are processes out there in nature to protect plants against flooding. The trick now is to pick them out, find them, and bring them into rice or other vulnerable crops."
The SUB1 gene
One example is the SUB1 gene, which became famous thanks to a study published in the scientific journal Nature in 2006.
SUB1 is the gene responsible for submergence tolerance. It was discovered in a low-yielding breed of rice in India. It was tediously cross-bred with high yielding varieties for years.
"It took a long time to introduce it to other varieties," said Dr. Abdelbagi Ismail, Principal Scientist and Plant Physiologist of IRRI.
"Actually until 1996, there was very little success. Few varieties have developed that are high yield that (also) have this gene."
In 1995 IRRI was able to map this gene. Using molecular markers, scientists were able to tell which varieties have the gene, and how much of the genome from the original plant was passed on to its "offspring." This process is called marker-assisted breeding, which quickened the cross-breeding process.
"Any variety when flooded in one week, it will die," said Dr. Abdelbagi Ismail, Principal Scientist and Plant Physiologist of IRRI. "But the varieties with the SUB1, they can withstand flooding even up to 16 to 18 days sometimes in the field."
The new plant was introduced in 2008. About three million farmers have planted these submergence-tolerant rice varieties in 2012.
Dream variety
At the moment, IRRI is working breeding rice varieties that are drought-tolerant and salinity tolerant as well.
"Our dream varieties are (those) that can tolerate drought, submergence, salinity, and actually we are developing these varieties now. We are hoping that in two or three years, we'll start releasing them," said Ismail.
But the level of tolerance developed this year will probably not be sufficient five to 10 years from now, he said.
"Fortunately, plant science now is advancing very quickly. We are learning a lot about adaptation—how plants adapt to these conditions. We go and study plants living in very tough conditions and learn from them and try to bring that information to improve crops."
Ismail said that with the advancements in genetics and genomics, and the sequences of rice genomes available, there is a lot of promise in the advancement of plant science.

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