Engineering Plant Enzymes for Enhanced Agricultural Productivity and Stress Tolerance

Biocatalysts or enzymes are natural, eco-friendly proteins that are essential for biochemical changes in all living beings. However, native enzymes are not reusable, unstable at extreme pH and temperature and are also costly for use in agriculture and industries. Engineering of enzymes to address these limitations involves exploiting structure–function relationships to create robust biocatalytic variants that are catalytically more efficient, have altered substrate specificity and will operate for longer. Some of these novel techniques including rational design, directed evolution, random mutagenesis, DNA shuffling, homology modeling and high throughput screening based on cell surface display allow the modification of existing enzymes to create valuable and cost-effective agricultural products. The engineering of plant enzymes to make them more tolerant to heat or acid, or to extract from biomass, has been less studied, but plant enzymes are known to be engineered to have enhanced properties for use in crops, disease resistance and yield. The design of plant biocatalytic systems, with higher abiotic stress resistance and productivity, has significant potential. The chapter presents a detailed description of the sophisticated techniques of protein engineering that have been developed to obtain catalytically superior and more thermostable and environmentally tough proteins. We explore some of the enzymes of plants–ascorbate peroxidase, papain, carbonic anhydrase and some glycoside hydrolases–that show how molecular optimization directly impacts crop stress adaptation and yields. Lastly, we highlight new, unconventional plant-derived enzymes that could be a valuable resource for scientific research in sustainable biotechnology.