Researchers identify new crops more tolerant to water shortage

The identified genes could enable different drought-resistant plants to survive in semi-arid conditions

Researchers have identified new drought-resistant plant genes that could accelerate the development of water-efficient crops. The identified genes could enable different drought-resistant plants to survive in semi-arid conditions.
According to the new study conducted by scientists at the US Department of Energy's Oak Ridge National Laboratory (ORNL), those genes could play a significant role in bioengineering and creating energy-producing crops that are tolerant to water deficits.
According to the study titled "Tthe Kalanchoë genome provides insights into convergent evolution and building blocks of crassulacean acid metabolism," crop production is the world's largest consumer of freshwater. Meanwhile, the availability of clean water resources is shrinking due to urbanisation, human population growth, and changes in climate, which present a challenge to optimal growing environments.
The study focuses on a form of photosynthesis, known as crassulacean acid metabolism (CAM), which has evolved over millions of years, and which is responsible for building water-saving characteristics in plants such as the orchid and pineapple, where the Kalanchoë genome has been latelyrecently identified. Kalanchoë works in plants growing in drylands by keeping their stomata, or pores, shut during the day to conserve water and open at night to collect carbon dioxide, according to the paper published in Nature Communications.
Integrating CAM photosynthesis into the production of food and high-energy crops could boost crop resilience when the water supply is less than desirable, and reduce agricultural water use, according to the study.
The ORNL-led team of researchers reached these findings through investigating and comparing the genomes of Kalanchoë fedtschenkoi, Phalaenopsis equestris (orchid) and Ananas comosus (pineapple) using ORNL's Titan supercomputer.
The team is studying a variety of drought-resistant plants to unlock the mystery of CAM photosynthesis. For this mission, they sequenced the genome Kalanchoë fedtschenkoi, an emerging model in CAM genomics research, due to its relatively small genome structure and amenability to genetic modification.
They identified 60 genes that exhibited convergent evolution in CAM-using species, including convergent daytime and night time gene expression changes in 54 genes, as well as protein sequence convergence in six genes.
"CAM is a proven mechanism for increasing water-use efficiency in plants. 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," ORNL co-author Xiaohan Yang said.
Yang added that it is widely accepted that some unrelated plants exhibit similar characteristics under similar environmental conditions, a process known as convergent evolution. He also explained that 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.
"If we can identify the mechanisms for water-use efficiency, we could move this trait into agronomic plants, supply non-potable water as irrigation to those plants, and save the clean water for drinking," said Jerry Tuskan, co-author and chief executive officer of the Center for Bioenergy Innovation led by ORNL.
Tuskan added that "studying the genome of water-efficient plants may also provide insights into a plant's ability to use slightly saline water and maintain growth under higher temperature and lower clean water availability."