Effect of gibberellins on metabolism during rosette growth in Arabidopsis. Arabidopsis thaliana

To understand the effect of high and low GA levels on plant metabolism and development in Arabidopsis we made use of the GA biosynthesis inhibitor paclobutrazol (PBZ) and exogenously applied GA. The whole genome response at the translation level was assessed by immunopurification of polysomes from PBZ- and GA treated plants expressing FLAG-tagged ribosomal protein L18 (RPL18B). Polysomal associated RNA was isolated and subjected to affymterix ATH1 CHIP analysis. A total of 140 genes were statistically determined to be differentially translated after GA treatment whereas 89 genes where affected PBZ treatment. Our analysis revealed that GA and PBZ have opposing effects on the expression of cell wall and wax layer biosynthesis related genes. In addition, many genes involved in secondary metabolism are upregulated upon PBZ treatment. A set of SAUR-like genes important for mediating auxin responses are downregulated by PBZ, which is of interest to coordinatian of GA levels with growth and development. Interestingly, GA treatment induces the upregulation of transcription factors related to plant defense and senescence, which is in agreement with the early flowering upon GA treatment. Our study provides a first picture of the response of Arabidopsis to altered GA levels at the translation level, and thus will be valuable for understanding gene regulation at the polysome level. Overall design: Two replicates for each treatment including GA, PBZ and control samples.