The mechanism of cell cycle repression by sprouting inhibitors

The potato is an important global crop that requires specialised storage to prevent sprouting and maintain quality between harvests. Chemical sprout suppressants are required but are increasingly regulated or banned due to potential environmental damage. Isopropyl N-(3-chlorophenyl) carbamate (CIPC) was the primary sprout suppressant in Europe prior to its ban. The mechanism of action of CIPC is poorly understood, hindering development of novel, alternative chemicals. Our current understanding of CIPC is mostly the result of microscopy-based investigations. In Chapter 2, I optimise an in vitro sprouting assay for identification of key timepoints in CIPC-suppressed sprouting and production of RNA samples. From imaging of sprouting buds using scanning electron microscopy, I characterised CIPC-induced changes in morphology, highlighting timepoints of interest. These images showed altered morphology from CIPC exposure which, to my knowledge, have not been documented in potato buds previously. In Chapter 3, I outline the creation and analysis of a novel RNA-sequencing dataset from the sprouting bud tissues, both with and without application of CIPC. This analysis identified many differentially expressed genes in response to CIPC treatment, with distinct differences between CIPC treatment and eco-dormant buds. Finally, in Chapter 4, I assay Arabidopsis T-DNA insertional mutants of candidate CIPC target genes selected from the RNA-sequencing dataset to detect lines with altered CIPC response. Several significant lines were identified and these lines provide insights into the mechanism of action of CIPC and offer avenues for further research.