Dissecting the role of cytokinin in root response to heat stress in Arabidopsis thaliana.

Abstract

Global food security is threatened by rising temperatures, which impair crop productivity. This study aimed to elucidate the molecular mechanisms enabling plant root adaptation to heat stress, focusing on the roles of cytokinin signalling, reactive oxygen species (ROS) regulation, and apoplastic pH in modulating root system resilience in Arabidopsis thaliana. Exogenous cytokinin application was found to enhance thermotolerance by reducing oxidative damage through ROS modulation in roots, although receptor mutants failed to exhibit similar antioxidant effects. Cytokinin was found to induce dynamic spatiotemporal alterations in apoplastic pH within root tissues. Moreover, a bidirectional relationship was revealed between cytokinin and pH, with exogenous pH changes reciprocally impacting cytokinin signalling intensity in roots. Acidic pH enhanced cytokinin responses, uncovering pH-mediated modulation of hormone signalling as a key factor in stress adaptation. This highlights the interconnectedness of hormonal, metabolic, and physiological factors orchestrating stress adaptation through a complex molecular interplay within plant root systems. The key findings significantly advance mechanistic understanding of the factors enabling root architecture preservation and function under temperature extremes. They provide a foundation for targeted interventions via biotechnology or agricultural strategies to improve crop heat tolerance and climate resilience by enhancing root thermotolerance. However, further validation across diverse genetic backgrounds is essential before translating these fundamental insights into implementable solutions. Overall, by elucidating the crosstalk between cytokinin, ROS, and apoplastic pH in the heat response in roots, this research makes important strides toward enabling precise crop improvement under global climate change.