A plant-specific calmodulin-binding protein, AtCBP60b mediates Ca2+ homeostasis and is critical for growth and development in temperature-dependent manner

Authors: CHENG, NINGHUI - Children'S Nutrition Research Center (CNRC); RAO, XIAOLAN - Hubei University; Nakata, Paul

Submitted to: Journal of Experimental Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/26/2026
Publication Date: 4/9/2026
Citation: Cheng, N., Rao, X., Nakata, P.A. 2026. A plant-specific calmodulin-binding protein, AtCBP60b mediates Ca2+ homeostasis and is critical for growth and development in temperature-dependent manner. Journal of Experimental Botany. https://doi.org/10.1093/jxb/erag164.
DOI: https://doi.org/10.1093/jxb/erag164

Interpretive Summary: Plant scientists have been avidly working to discover new strategies to improve our ability to grow and produce food crops. In this report, we investigate the role of a transcription factor, called CBP60b, in controlling plant growth and development. We determined using genetics that CBP60b is essential for normal plant growth and development in Arabidopsis. Deleting this CBP60b gene in Arabidopsis resulted in a dramatic reduction in plant size, decrease in cell number, increase in cell size, and a delay in plant development. Using molecular genomics we analyzed the expression of all the genes in the normal Arabidopsis plant and a plant lacking the CBP60b gene. We determine, using computer analysis, that the genes associated with the processes of plant growth, cell division, and calcium transport were expressed less in the smaller plant lacking the CBP60b gene compared to the normal Arabidopsis plant. The genes involved in the process of plant immunity were found to be expressed more in the smaller plant lacking the CBP60b gene than the normal Arabidopsis plant. We show, using a combination of biochemistry and molecular biology that CBP60b controls the transcription of the genes associated with the process mentioned above and this control requires the binding of a second protein called calmodulin. Temperature studies also revealed that growing the smaller plant lacking the CBP60b gene at a higher growth temperature returns its growth and development back to normal. Overall, this study gives us a better understanding of the factors regulating plant growth and development. Such an understanding is necessary in developing strategies to improve our ability to grow and produce crop foods.

Technical Abstract: Calcium (Ca2+) is an essential mineral nutrient and a vital signaling molecule for plant growth and organ development. Ca2+/calmodulins (CaMs) can bind or interact with proteins, called CaM binding proteins (CBPs), to relay Ca2+ signals and modulate transcriptional activity. In this study, we demonstrate that AtCBP60b, a member of CBP60 family, is an essential factor in regulating plant growth and organ development. AtCBP60b loss of function plants showed impaired seedling growth, leaf development, and plant structural architecture under normal growth condition. Transcriptomic profiles indicated a central role for AtCBP60b in the transcriptional regulation of Ca2+ signaling pathway, growth homeostasis, immune, and stress responses. Disruption of AtCBP60b leads to Ca2+ deficiency hypersensitivity, reduced cytosolic Ca2+ concentration and altered Ca2+ signaling responses. AtCBP60b was found to bind calmodulin which was determined to be required for AtCBP60b function in transcriptional regulation of the genes encoding the pathways regulating calcium homeostasis and signaling, defense response, and plant growth and development. In addition, we show that elevated temperatures can rescue the Atcpb60b growth and development defects through reprogramming of the transcriptional profiles of the genes regulating these processes. Overall, our findings provide a nexus between the pathways regulating plant Ca2+ signaling and homeostasis, growth and development, and responses to elevated temperature.