Thiamine and Its Role in Protection Against Stress in Plants (Enhancement in Thiamine Content for Nutritional Quality Improvement)

Thiamine or vitamin B1 plays an indispensable role in many metabolic reactions. The active form, thiamine pyrophosphate (TPP), functions as a cofactor in various crucial metabolic reactions including glycolysis, pentose phosphate pathway, and the tricarboxylic acid cycle in all living organisms. Recently, thiamine is also associated with the induction of systemic acquired resistance (SAR) in the plant. It has also been shown that thiamine has a role in boosting plants’ immunity and defence system. Many plants have been investigated and indeed thiamine may be one of the key molecules involved in plant protection against stress. Numerous studies have shown that the expression of thiamine biosynthesis genes was upregulated upon both biotic and abiotic stress induction in various plants. Various analyses including looking at the expression of thiamine biosynthesis genes, the accumulation of thiamine and its intermediates and also on enzyme function complementation studies have supported the role that thiamine may play in plant protection. In this chapter, the role of thiamine as a stress-responsive signalling molecule, its biosynthesis pathway and how it is being regulated will be discussed. The application that entails the understanding of this role will be briefly described and hence provide the support for the suggestion of its role in protection against stress in plants.