Photosynthetic Resilience Under Stress: Unraveling The Role Of Phytohormones And Phytometabolites

Photosynthetic organisms grow in diverse habitats and also continuously deal with the fluctuating environmental conditions. The changes in the environmental factors such as intensity and quality of light, salt and nutrient concentrations, temperature extremes, and heavy metal contaminations widely affect the growth and photosynthetic efficiency of the phototrophs. However, these organisms display outstanding ability to cope up with such adverse conditions present on the earth, which is the result of resilience in the photosynthesis. Phototrophs show resistance against ever changing environmental conditions up to a certain level by maintaining their photosynthetic yield. Some phytochemicals such as secondary metabolites and phytohormones play crucial role in the resilient behavior of photosynthesis. Among phytometabolites, alpha tocopherol plays a potent role in scavenging reactive oxygen species under adverse conditions. In phototrophs, during the synthesis of alpha-tocopherol, gamma tocopherol, a phytometabolite is converted into alpha tocopherol via gamma tocopherol methyl transferase (gamma TMT) enzyme in final rate-limiting step. This enzyme has been successfully characterized in plants, but annotation and characterization are still lacking in cyanobacteria. So, diversity and phylogenetic analyses of methyltransferase domain, responsible for gamma TMT activity, have been done in this chapter. After bioinformatic analysis, it was found that some amino acid residues are conserved among domain found in all three groups of phototrophs, and these residues may be crucial for the activity of gamma TMT. Additionally, molecular docking was performed between gamma TMT-containing domain protein (Nostoc sphaeroides CCNUC1) and gamma-tocopherol to validate the interaction between them. Moreover, there are some literature that individually define.