Engineering Crassulacean Acid Metabolism to Improve Water-Use Efficiency

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A novel technology to increase the water-use efficiency and drought tolerance in plants using synthetic biological approaches. Crassulacean acid metabolisms (CAM) is a specialized form of photosynthesis that reduces crop water demands by 3-to-6-fold compared with non-CAM species by shifting all or part of atmospheric CO2 fixation from the day, when water loss due to evapotranspiration is high to the cooler night, when these losses are much lower. Engineered CAM can improve the overall carbon budget of the plant leading to improved growth and biomass production especially under the hotter and drier conditions of the future.  Bioengineered CAM also dramatically improves drought tolerance.


The genetic engineering of CAM was developed using the constitutive and drought-inducible expression of various gene circuits expressing the enzymes and regulators required for the operation of the carboxylation and decarboxylation modules of CAM and the complete CAM cycle in a C3 (or C4) photosynthesis host plant.


  • Plants grow larger with increased biomass and seed production
  • Improves drought tolerance
  • Improves water-use efficiency
  • Crop production requires lower water inputs.






Fig. 1. Engineered Crassulacean acid metabolism confers drought stress tolerance. A) Water was withheld from plants for 16 d. B) Water was withheld from plants for 18 d and the rewatered and allowed to recover for 3 d. Wild-type control plants (WT). Carboxylation gene circuit (CGC). Decarboxylation gene circuit (DGC). Complete CAM circuit (CAM). Three WT or independent transformants (#1, #2, and #3) are shown for each gene circuit. C) Survival rates (n = 60). Values represents means ±s.d., ns, non-significant, ***p < 0.001. One-way ANOVA with Dunnett’s multiple comparison test.



Patent Information:
For Information, Contact:
David Maine
Senior Licensing Associate
University of Nevada, Reno
John Cushman
Sung Lim
Won Cheol Yim