Location: Physiology and Pathology of Tree Fruits Research
Title: Microscopic study of lignin deposition patterns in young apple roots during defense activation in response to Pythium ultimum infection [abstract]Author
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Submitted to: APS Annual Meeting
Publication Type: Abstract Only Publication Acceptance Date: 3/16/2023 Publication Date: 8/25/2023 Citation: Zhu, Y., Rainbow, J.L. 2023. Microscopic study of lignin deposition patterns in young apple roots during defense activation in response to Pythium ultimum infection [abstract]. APS Annual Meeting. Paper No. 268. Interpretive Summary: Technical Abstract: Our recent transcriptome analyses have uncovered a multi-phase and multi-layer defense tactic in apple roots against infection from the necrotrophic oomycete pathogen, Pythium ultimum. Notable transcriptome changes specifically associated with effective defense activation include upregulation of the phenylpropanoid biosynthesis pathway, robust secondary metabolite transport, and enhanced laccase-directed lignin formation. By taking advantage of lignin-specific staining methods and lignin autofluorescence, we investigated lignin deposition in young apple roots with and without infection and between resistant and susceptible apple rootstock genotypes. Preliminary data indicated that, compared to the Wiesner test, the Maule test is a more effective lignin staining method for young apple root tissue. Using both bright-field and fluorescence imaging, the intensity of lignin deposition was elevated in the parenchyma cells of infected root cortex tissues. Genotype-specific lignin deposition patterns, particularly around vascular bundles, indicated that inherent variation in lignin richness and composition may also be associated with the observed resistance traits. In order to define the functional roles of identified genes and pathways in apple root resistance traits, it is crucial to develop reliable methods to detect anatomical and biochemical changes such as cell wall lignification. |
