Decoding Sugar Regulation and Homeostasis in Plants: Cracking Functional Roles Under Stresses

The plant system has been endowed with highly extensive defence system in order to protect them under severe environmental conditions. In response to adversities, plants have well developed and complexed metabolic network that comprises stress-responsive genes and metabolites for stress acclimation. Sugars are the part of many metabolic processes such as photosynthesis that plays crucial role in maintaining osmotic balance as well as sugar homeostasis. During stresses, they play critical role in stress perception as well as signalling and act as regulatory circuit for stress-mediated responses encoding for osmotic adjustments, ROS scavenging and cellular homeostasis. Numerous sugar transporters have been identified in carbohydrate partitioning along with signal transduction pathways in plants subjected to stresses. Specific sugar transporters, namely, SUGARS WILL EVENTUALLY BE EXPORTED TRANSPORTER (SWEETs), POLYOLS TRANSPORTERS, SUCROSE TRANSPORTERS (SUTs), ORGANELLES SUGAR TRANSPORTERS, MONOSACCHARIDE TRANSPORTERS (MSTs) and SUGAR TRANSPORTER PROTEIN are predominantly involved for sugar loading/unloading and long-distance transport followed by stress tolerance. Therefore, it is essential to gain knowledge about structure and functions of sugar transporters and homeostasis in plants under stressed conditions. Advancement in studies have explored different sugar signalling cascades and their crosstalk during stressed conditions. Moreover, integrated approaches also enable the identification as well as characterisation of sugar transporters that may act as targets for stress resistance in plants along with enhancing crop yield and productivity. The present review aims at updated knowledge about sugar homeostasis in plants during stressed conditions along with detailed understanding about sugar transporters.