US Partnering Award: Elucidating the Chloroplast Derived Signals Driving Initiation of Plant Systemic Acquired Immunity.

Summary: This USA Partnering Award application has been catalyzed by recent discoveries in the Grant lab on chloroplast immunity (Understanding the mechanism of chloroplast immunity, BB/P002560/1) that provides evidence for a pivotal role of the chloroplast in the generation of the immunizing signal necessary for activation of systemic acquired resistance (SAR; also known as systemic immunity). The application aims to establish collaborative links with the Grant lab (MG) and those of Pradeep Kachroo (PK) and Aardra Kachroo (AK) in the Department of Plant Pathology at the University of Kentucky, Lexington, USA. By doing so we can combine a unique set of tools, expertise and facilities to better understand plant systemic immunity. Why the USA lab? Systemic immunity, established following an immunizing challenge, makes a whole plant more resistant to a range of diverse pathogens. SAR is not triggered by a single generic signal but is rather, a multi-faceted process1-5. The Kachroo labs have emerged as the world-leading group in elucidating the complex processes involved in SAR. They have pioneered the discovery and functional characterization of a number of small molecules that, following a local defence response, collectively function to induce broad spectrum systemic immunity in systemic leaves. Driver: A mechanistic understanding of systemic immunity has wide ranging implications from a food security perspective and knowledge of the bioactives has enormous agri-chemical potential. Recent research has firmly established a pivotal role for chloroplasts in underpinning plant innate immune responses. Chloroplasts have been shown to be central components of Microbe Associated Molecular Pattern triggered immunity (described by MG6), effector triggered immunity7 and – the focus of this Partnering Award – systemic immunity. The driver behind establishing this collaboration is the combination of recent results emerging from the MG lab and the immense contribution the PK/AK labs have made during the past 5-6 years in elucidating the signaling processes underpinning SAR. These collective results unequivocally demonstrate a clear link to chloroplasts and systemic immunity. MG and PK met at the EBMO Conference on Plasmodesmata in Berlin this summer and shared results. It was clear there were tremendous synergies to be gained through collaboration that would accelerate progress in understanding SAR signaling by using the respective expertise and sharing access to the tools and facilities.