A simple and efficient -mediated transient expression system to dissect molecular processes in and .

Unlabelled: The family Brassicaceae is a source of important crop species, including (oilseed rape), , and , that is used globally for oil production or as a food source ( pak choi or turnip). However, despite advances in recent years, including genome sequencing, a lack of established tools tailored to the study of crop species has impeded efforts to understand their molecular processes in greater detail. Here, we describe the use of a simple -mediated transient expression system adapted to and that could facilitate study of molecular and biochemical events in these species. We also demonstrate the use of this method to characterize the N-degron pathway of protein degradation in . The N-degron pathway is a subset of the ubiquitin-proteasome system and represents a mechanism through which proteins may be targeted for degradation based on the identity of their N-terminal amino acid residue. Interestingly, N-degron-mediated processes in plants have been implicated in the regulation of traits with potential agronomic importance, including the responses to pathogens and to abiotic stresses such as flooding tolerance. The stability of transiently expressed N-degron reporter proteins in indicates that its N-degron pathway is highly conserved with that of . These findings highlight the utility of -mediated transient expression in and and establish a framework to investigate the N-degron pathway and its roles in regulating agronomical traits in these species.

Significance Statement: We describe an mediated transient expression system applicable to crops and demonstrate its utility by identifying the destabilizing residues of the N-degron pathway in . As the N-degron pathway functions as an integrator of environmental signals, this study could facilitate efforts to improve the robustness of crops.