Secrets of succulents’ water use revealed – sciencedaily
Plant scientists at the University of Liverpool have revealed new knowledge about the mechanisms that allow certain plants to conserve water and tolerate drought.
The research, published in The plant cell, could be used to help grow new crops that can thrive in previously inhospitable, hot and dry regions around the world.
Drought tolerant plants, such as cacti, agaves, and succulents, use an enhanced form of photosynthesis known as Crassulacean Acid Metabolism, or CAM, to minimize water loss.
Photosynthesis involves taking carbon dioxide from the atmosphere and turning it into sugars using sunlight. Unlike other factories, CAM factories are able to absorb CO2 during the cooler night, which reduces water loss and stores captured CO2 in the form of malic acid inside the cell, allowing its use for photosynthesis without loss of water the next day.
CAM photosynthesis is regulated by the plant’s internal circadian clock, which allows plants to differentiate and anticipate day and night and adjust their metabolism accordingly. However, relatively little is known about the exact molecular processes underlying the optimal timing of CO2 stored and released in this unique way.
A team of researchers from the University’s Institute for Integrative Biology examined an enzyme of interest called PPCK which is involved in controlling the conversion of CO2 to its form stored overnight (malic acid; the fruit acid which gives a tangy taste to apples) and vice versa. They wanted to know if PPCK was a necessary component for engineering CAM photosynthesis and tested it by turning off the PPCK gene in the CAM succulent plant. Kalanchoe fedtschenkoi.
They found that for CAM to work properly, cells must activate PPCK every night based on their internal circadian clock. When they stopped Kalanchoë from making PPCK at night, the plants were only able to pick up a third of the CO2 captured by normal plants.
In addition, they found that plants unable to make PPCK every night exhibited alterations in their circadian clock, a surprising finding that suggests that metabolites associated with CAM communicate time of day information to the clock. central plant.
Dr James Hartwell commented: “Drought is a key cause of crop loss around the world, so it is essential to understand the mechanisms by which certain desert-adapted plants have evolved to survive water stress to improve tolerance to drought. drought of cultivated species.
“Our work demonstrates that ongoing efforts to design CAM photosynthesis in other plants will need to include PPCK. The unexpected complexity we have revealed in the relationship between PPCK, CAM and the circadian clock also highlights the need to continue researching CAM processes before they can fully understand and exploit their pathways. “
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