ABSTRACT
Optimal environmental conditions substantially influence all aspects of plant survival and abiotic constraints such as salinity, drought, chilling and high temperature adversely affect their growth. These limitations pose serious threats to plant growth and yield by inactivating enzymes, causing protein denaturation, disrupting membrane structure, and producing toxic chemicals such as Reactive Oxygen Species (ROS). Naturally, plants have mechanisms to perceive stress and generate appropriate molecular and cellular responses due to active signaling networks (transcriptional regulators, transducer, and metabolites). Moreover, numerous chemical compounds such as phytohormones, antioxidant chemicals, anti-oxidative enzymes, low-molecular-weight osmolytes (proline, glycine, betaine, sugars, amines), trace elements and signaling molecules (NO, H2O2) act as phytoprotectants. They modulate the signaling cascades and confer tolerance to plants against numerous abiotic stresses. These protectants have a potential role in different cellular events, such as gene expression, activation of transcriptional networking like bZIP through phosphorylation and crosstalk between different signaling pathways, leading to robust defense responses. A better understanding of these protectants that mediate tolerance in plants will help in the genetic engineering of crops for better stress tolerance with their enhanced production. This chapter will focus on the importance of these protectants for the acclimation in adverse environmental conditions and their effect on plant physiology in modulating abiotic stress signaling.
