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Plant tissue engineering improves drought and salinity tolerance Jul 03, 2020 | 14:13 / Interesting information

After several years of experimentation, scientists have engineered thale cress, or Arabidopsis thaliana, to behave like a succulent, improving water-use efficiency, salinity tolerance and reducing the effects of drought. "Water-storing tissue is one of the most successful adaptations in plants that enables them to survive long periods of drought. This anatomical trait will become more important as global temperatures rise, increasing the magnitude and duration of drought events during the 21st century," said University of Nevada, Reno Biochemistry and Molecular Biology Professor John Cushman, co-author of a new scientific paper on plant tissue succulence published in the Plant Journal. The work will be combined with another of Cushman's projects: engineering another trait called crassulacean acid metabolism (CAM), a water-conserving mode of photosynthesis that can be applied to plants to improve water-use efficiency. Cushman's team of scientists created genetically modified A. thaliana with increased cell size resulting in larger plants with increased leaf thickness, more water-storage capacity, and fewer and less open stomatal pores to limit water loss from the leaf due to the overexpression of a gene, known as VvCEB1 to scientists. "Larger cells have larger vacuoles to store malate at night, which serves as the carbon source for carbon dioxide release and refixation, by what's called Rubisco enzyme action, during the day behind closed stomatal pores, thereby limiting photorespiration and water loss" Cushman said. "And, the succulent tissue traps the carbon dioxide that is released during the day from the decarboxylation of malate so that it can be refixed more efficiently by Rubisco. CAM plants are very smart, keeping their stomata closed during the day, and only opening them at night when evapotranspiration is low because it is cooler and the sun is not shining,” Cushman explained. The significance of CAM is found in its unique ability to conserve water. Where most plants would take in carbon dioxide during the day, CAM plants do so at night. "We plan to move both tissue succulence and CAM engineering into crop plants. This current work is proof-of-concept," Cushman said.

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