Biosynthesis, Signaling, Homeostasis, Transport, and Regulatory Mechanisms of Cytokinin in Rice and Arabidopsis Response to Heat Stress

Plants are occasionally exposed to various biotic and abiotic stresses throughout their growth and developmental stages, which significantly impacts crop production and poses a significant threat to global food security. Among abiotic stresses, heat stress (HS) expressively affects growth and drastically reduces crop yield due to changing the morphology and physiology of plants. Cytokinin (CK) is a plant hormone that successfully activates stress-responsive regulatory genes and plays a critical role in protecting plants against HS. However, the processes of CK-alleviating stress vary across a diversity of stress interactions. To optimize CK utilization in agriculture and enhance crop yield, it is important to understand how CK functions in challenging environments. In this review, we addressed CK-regulated functions including their biosynthesis and metabolism, signaling pathways with related gene regulation, transport mechanisms, homeostasis, and diverse roles with a special focus on their contribution to plant growth, development, and HS resistance in rice and Arabidopsis. We have provided a comprehensive summary of recent findings on the CK-mediated processes of plant growth, development, and responses to HS, aiming to disseminate a comprehensive overview of how CK coordinates crucial signals in this process. Our review might lead to identifying key areas for further study and future potential application prospects in stress resistance research.