Scientific finding paves way for rice genetic engineering to develop efficient water storage

June 29, 2017 - 6:58 PM
stomata and chloroblasts
Illustration of the role of chloroblasts on activation of stomata on a leaf structure.

Researchers at the Australian National University (ANU) have found a way to survive drought conditions 50 percent longer by leveraging chloroplasts to initiate the conservation of water by causing plant pores or stoma to close as temperatures rise.

The plant pumps water into the leaves, which, in turn, absorb carbon dioxide. Chlorophyll, water, carbon dioxide, and other food producing substances are available inside the chloroplast, and the entire process of photosynthesis takes place in the chloroplast.

Scientists observed that chloroplasts can sense drought stress and always activate a chemical that closes the plant’s pores or stomata to conserve water.

A rice variety efficient in storing water, similar to the Submarino series developed by the Philippine Rice Research Institute, could help boost Philippine rice production, which is hobbled annually by an estimated deficit ranging from 8.5 percent to 10 percent.

This finding was revealed in the article written by lead author Dr. Wannarat Pornsiriwong and others entitled “A chloroplast retrograde signal, 3′-phosphoadenosine5′-phosphate, acts as a secondary messenger in abscisic acid signaling in stomatal closure and germination,” in the peer-reviewed journal eLife on March 21, 2017.

The research team, led by Dr. Wannarat Pornsiriwong, Dr. Gonzalo Estavillo, Dr. Kai Chan and Dr. Barry Pogson from the Australian National University (ANU) Research School of Biology, found that chloroplasts, better known for their role in photosynthesis, play a role in regulating plant response during heat stress.

“Chloroplasts are actually capable of sensing drought stress and telling the leaves to shut up and prevent water from being lost during drought stress,” Dr. Pogson added.

“So the chloroplasts are actually helping the plants to prevent losing too much water. We know how the drought alarm actually calls for help and we know how help comes in the form of closing pores on the leaves,” he stressed.

“Boosting the levels of this chloroplast signal also restores tolerance in drought-sensitive plants and extended their drought survival by about 50 per cent,” Dr. Chan added.

By increasing the activity of the chloroplasts or stimulating this chemical signal in another way, plants could store water for a longer period and survive despite higher temperatures.

Through this specific function of chloroplasts, plant geneticists may employ genetic modification (GM) to develop plants with more spores or crops that have roots and stems big enough to store water the way pineapple, watermelon and turnips do.

This finding is significant as climatologists have predicted more intense global warming that could reduce rice yields.

The finding would also boost efforts by biotechnologists and plant breeders to coax rice varieties to use their chloroplasts efficiently to help the plants store water and thus support a bigger volume of rice grains in a panicle.

“This basic scientific research has the potential to improve farming productivity … in countries that suffer from drought stress,” Dr. Pogson said.

“If we can even alleviate drought stress a little, it would have a significant impact on our farmers and the economy,” he added.