Scientists aim to develop drought-resistant crops using genetic engineering

Researchers have identified the genetic underpinnings of drought resistant plants, allowing them to potentially develop crops that could grow, and even thrive, in dry conditions.

Crop production is one the world’s largest consumers of fresh water, a supply under threat by a growing world population and increased urbanisation. Crops that require less water could be hugely beneficial in semi-arid parts of the world, where crop failures can be disastrous for local populations.

Drought-resistant plants share a mechanism known as crassulacean acid metabolism, or CAM, which allows them to survive despite low levels of water.

In a new study, published in the journal Nature Communications, a team of researchers has identified the set of genes underpinning CAM, laying the groundwork for future genetic engineering of food crops.

“CAM is a proven mechanism for increasing water-use efficiency in plants,” said Dr Xiaohan Yang, a plant biologist at the US Department of Energy’s Oak Ridge National Laboratory and co-author of the new study.

CAM is essentially a form of photosynthesis in which the pores in a plant’s leaves only open to let in carbon dioxide at night.

During the day, when the sun is out, the pores remain closed in order to prevent water escaping through them. This means they are better able to tolerate dry conditions.

“As we reveal the building blocks that make up CAM photosynthesis, we will be able to bioengineer the metabolic processes of water-heavy crops such as rice, wheat, soybeans and poplar to accelerate their adaptation to water-limited environments,” he said.

Dr Yang and his collaborators looked at the genomes of three plant species that use CAM, including orchids and pineapples.

In doing so, they found 60 genes that had evolved in the same way in all three different species to give them CAM.

These genes are the “building blocks” that Dr Yang referred to, which had evolved independently in a process known as “convergent evolution” to produce the same mechanism in all three species.

The research team hope that with the knowledge of these genes, they could engineer the capacity for CAM into food and energy crops. This could allow crops to be grown in previously impossible environments, or provide them with greater resilience when faced with unfavourable climates.

“These convergent changes in gene expression and protein sequences could be introduced into plants that rely on traditional photosynthesis, accelerating their evolution to become more water-use efficient,” said Dr Yang.