Understanding the mechanisms underlying herbicide synergy

Herbicide synergies are desirable, allowing lower application rates, or frequency of treatments, reducing the incidence of herbicide resistance and conferring effects across a greater range of weed species. Although herbicide synergies appear to be rare and unpredictable, synergism between 4-hydroxyphenylpyruvate dioxygenase (HPPD) and Photosystem II (PSII) inhibitors are well documented and have been confirmed in industrial relevant environments [1]. However, the underlying mechanisms delivering the synergistic effects, beyond additive predictions, remain elusive. A common feature between HPPD and PSII inhibitors is the involvement of plastoquinone (PQ), a molecule involved in multiple plastid biosynthetic pathways and essential biological processes. HPPD inhibitors block the formation of plastoquinone, while PSII inhibitors impair the transport of electrons to the PQ pool [2]. Our challenge now, is to employ innovative technologies/approaches to decipher the direct and indirect effects associated with the combined effects of HPPD/PSII inhibitors, to reveal plausible mechanistic explanations for their synergism.

Our aim is to elucidate the underlying biochemical and molecular mechanisms associated with synergistic herbicidal combinations. To achieve this goal the known synergistic herbicidal combination(s) of HPPD and PSII herbicides will be used. Following the establishment of in vitro cultivation techniques, modern metabolomic and proteomic approaches to determine changes in metabolite pools associated with HPPD and PS II inhibitors independently and in combination. To validate direct and indirect metabolite changes observed genetic resources conferring resistant HPPD and PS II inhibitors will be used.

The host laboratory is well funded and equipped, with dedicated GC-MS (x3), GC-FID, HPLC-PDA (x3), a HPLC-PDA-radiodetector, UPLC-PDA, and numerous real-time PCR machines. The laboratory has dedicated plant growth facilities. Customised MS libraries have been developed [3 & 4]. High throughput modular cloning and an extensive repository of DNA parts available for Synthetic Biology. Recent investments include a suite of state-of-the-art hyphenated MS platforms.

The group's involvement in European networks (H2020 and COST ACTIONS) means that students are provided with the opportunity to carry out work in laboratories abroad as part of their interdisciplinary training, while the CASE partner facilitates direct industrial interaction. Collectively the studentship will provide excellent first-hand training in plant physiology, cell biology, biochemistry, molecular biology all in an applied industrial format.