Genetic and molecular mechanisms underlying root architecture and function under heat stress - A hidden story.

Heat stress events are resulting in a significant negative impact on global food production. The dynamics of cellular, molecular and physiological homeostasis in aboveground parts under heat stress are extensively deciphered. However, root responses to higher soil/air temperature or stress signaling from shoot to root are limited. Therefore, this review presents a holistic view of root physio-morphological and molecular responses to adapt under hotter environments. Heat stress reprograms root cellular machinery, including crosstalk between genes, phytohormones, reactive oxygen species (ROS), and antioxidants. Spatio-temporal regulation and long-distance transport of phytohormones such as auxin, cytokinin, and abscisic acid (ABA) determines the root growth and development under heat stress. ABA cardinally integrates a signaling pathway involving heat shock factors, heat shock proteins, and ROS to govern heat stress responses. Additionally, epigenetic modifications by transposable elements, DNA methylation, and acetylation also regulate root growth under heat stress. Exogenous application of chemical compounds or biological agents such as ascorbic acid, metal ion chelators, fungi, and bacteria can alleviate heat stress induced reduction in root biomass. Future research should focus on the systemic effect of heat stress from shoot to root with more detailed investigations to decipher the molecular cues underlying the architectural changes. This article is protected by copyright. All rights reserved.