Advances on Molecular Mechanisms of Plant Balanced Growth and Development and Response to Stress

Due to the characteristics of fixed growth, plants cannot effectively avoid external unfavorable factors like animals. Therefore, its growth and development will be affected by various adversity stresses. A timely and effective response to these adversity stresses is a prerequisite for plant survival. The plant hormone Abscisic acid (ABA) is called "adversity hormone", and it participates in the response process of plants to drought, cold, and salt stress. Brassinosteroid (BR) signaling pathway participates in processes such as cell division and controls plant growth and development. Exploring the signal cross-interaction between two important pathways can better understand how plants switch between growth and development and response to adversity to maintain vitality. Xie Qi, a researcher at the Institute of Genetics and Developmental Biology of the Chinese Academy of Sciences, published a titled Balancing growth and adaptation to stress: crosstalk between brassinosteroid and abscisic acid signaling (DOI: 10.1111/pce.13846) in Plant Cell and Environment. A review article that elaborates on this process and discusses urgent problems and future research directions.   By summarizing the molecular mechanism of the signal crossing of ABA and BR signaling pathways, it is found that the two mainly regulate each other in an antagonistic manner. That is when subjected to adversity stress, plants will activate ABA signals and inhibit the growth and development process mediated by BR signals to a certain extent; BR signals can inhibit ABA signals to ensure normal plant growth and development under non-stress conditions. Studies have found that the mutual regulation between ABA and BR occurs at multiple levels. The two can regulate the expression or activity of transcription factors such as ABI3, ABI5, and BZR1, so that extensive signal exchange occurs at the transcription level. Both of them regulate important protein modifications such as phosphorylation, dephosphorylation, and ubiquitination to change their activity or stability and regulate them at the level of protein post-translational modification. Multi-level and multi-modal regulation and extensive communication between the two and other hormone signals form a complex regulatory network that enables plants to maintain a dynamic balance between growth and development and response to stress. In addition, the study compared the similarities and differences between model plants and crops in the cross-regulation of ABA and BR signaling pathways, and provided certain guidance for the improvement of crops with both stress resistance and high yield traits.