Transcriptomic evidence of a link between cell wall biogenesis, pathogenesis, and vigor in walnut root and trunk diseases

Authors: SAXE, HOUSTON - University Of California, Davis; WALAWAGE, SRIEMA - University Of California, Davis; BALAN, BIPIN - University Of California, Davis; LESLIE, CHARLES - University Of California, Davis; BROWN, PATRICK - University Of California, Davis; Browne, Greg; Kluepfel, Daniel; WESTPHAL, ANDREAS - University Of California, Riverside; DANDEKAR, ABHAYA - University Of California, Davis

Submitted to: International Journal of Molecular Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/8/2024
Publication Date: 1/11/2024
Citation: Saxe, H., Walawage, S., Balan, B., Leslie, C., Brown, P.J., Browne, G.T., Kluepfel, D.A., Westphal, A., Dandekar, A.M. 2024. Transcriptomic evidence of a link between cell wall biogenesis, pathogenesis, and vigor in walnut root and trunk diseases. International Journal of Molecular Sciences. 25(2). Article 931. https://doi.org/10.3390/ijms25020931.
DOI: https://doi.org/10.3390/ijms25020931

Interpretive Summary:

Technical Abstract: Agrobacterium tumefaciens (Crown Gall Disease), Phytophthora (Phytophthora crown and root rot), and Pratylenchus vulnus (Root Lesion Nematode) are the leading rootstock pathogens and pests of walnut limiting their productivity and quality in California. Recent walnut breeding efforts have generated hundreds of hybrid rootstocks to capture natural sources of resistance to these pathogens and pests. To uncover potential pre-formed resistance factors, we performed transcriptomic analysis without pathogen challenge of six selected hybrids that vary in their disease phenotype. Principal component analysis revealed unique transcriptomic profiles associated with each disease trait, suggesting the uninfected transcriptional repertoires are critical resistance and that this may be a basal defense mechanism. Modeling of the expressed genes revealed coexpressed genes associated with each disease trait, many of which were shared across traits. Gene Ontology Overrepresentation Analysis of these coexpressed genes suggested that host cell wall biogenesis may play a key role in defense. Furthermore, BUSCA subcellular localization analysis showed that, on average, the genes most associated with resistance were targeted to the plasma membrane and extracellular apoplastic space, implicating barrier function as a potential resistance factor in these diseases. This research suggests that cell wall biogenesis and barrier function are likely involved in Crown Gall Disease, Phytophthora crown and root rot, and Root Lesion Nematode and that modulation of these processes may modulate disease resistance.