The hormone gibberellin (GA) controls plant growth and regulates growth responses to environmental stress. In monocotyledonous leaves, GA controls growth by regulating division-zone size. We used a systems approach to investigate the establishment of the GA distribution in the maize leaf growth zone to understand how drought and cold alter leaf growth. By developing and parameterizing a multiscale computational model that includes cell movement, growth-induced dilution and metabolic activities, we revealed that the GA distribution is predominantly determined by variations in GA metabolism. Considering wild-type and UBI::GA20-OX-1 leaves, the model predicted the peak in GA concentration, which has been shown to determine division-zone size. Drought and cold modified enzyme transcript levels, although the model revealed that this did not explain the observed GA distributions. Instead, the model predicted that GA distributions are also mediated by post-transcriptional modifications increasing the activity of GA20oxidase in drought and of GA2oxidase in cold, which we confirmed by enzyme activity measurements. This work provides a new, mechanistic understanding of the GA metabolism in plant growth regulation.
Band, L. R., Nelissen, H., Preston, S. P., Rymen, B., Prinsen, E., Abd Elgawad, H., & Beemster, G. T. S. (2022). Modelling reveals post-transcriptional regulation of GA metabolism enzymes in response to drought and cold. Proceedings of the National Academy of Sciences, 119(31), Article e2121288119. https://doi.org/10.1073/pnas.2121288119