Hypersensitive response (HR)-conferred resistance is an effective defense response determined by the resistance (R) genes. In potato cv. Rywal, HR is initiated by the Ny‐1 gene and is manifested as the formation of necrotic lesions on inoculated leaves. Whereas the activation of R proteins has been intensively studied, the downstream signaling mechanisms leading to the restriction of the pathogen remain mostly unknown.
HR is preceded by a series of biochemical and cellular signals, including salicylic acid (SA) biosynthesis, accumulation of redox oxidative species (ROS) in different subcellular compartments and stromules (stroma filled tubules that extend from chloroplasts) formation. Precise temporal and spatial coordination of induced signaling pathways is required to successfully restrict the pathogen with minimal damage to the host. Thus, it is crucial to understand the interconnectedness between the key players of HR-conferred resistance.
The aim of the proposed research project is to evaluate the connection between apoplastic ROS, chloroplastic ROS, SA and stromule formation and its role in HR-conferred resistance.
We hypothesize that HR is a process where the precise spatiotemporal regulation of organelle specific ROS, SA levels and stromule induction is crucial for the effectiveness of viral arrest. The change of organelle specific ROS and SA levels in various combinations alter the rate of cell-to-cell and systemic virus spread, rate of cell death induction, frequency of stromules formation and spatial transcriptional response in HR-conferred resistance. We suggest that only a coordinated and intertwined action of all key players enable effective immune response.
We will address this hypothesis through the following specific objectives:
- To evaluate the impact of apoROS and SA on chloroplastic redox state and stromules formation with spatiotemporal resolution
- To decipher how the connection between apoROS, chlROS, SA and stromule formation regulates viral cell-to-cell movement, systemic virus spread and HR cell death initiation
- To identify previously unknown key players of HR-conferred resistance by spatial non-targeted transcriptomics
- To unravel the role of stromules in HR-conferred resistance