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United States Department of Agriculture

Agricultural Research Service

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Research Project: Utilizing High Resolution Computed Tomography to Visualize Early Stages of Wood Canker Disease in Resistant and Susceptible Grapevines

Location: Crops Pathology and Genetics Research

2012 Annual Report


1a.Objectives (from AD-416):
Using High Resolution Computed Tomography (a type of CAT scan) to assess the following objectives: 1)Characterize the early stages of wood canker infection with unprecendented resolution on intact and excised woody portions of grapevines; and 2)Examine the influence of drought stress on the progression of early stages of infection.


1b.Approach (from AD-416):
High Resolution Computed Tomography (HRCT-a type of CAT scan) technology and custom software has recently been developed and used in the lab to analyze fine scale details of xylem that contribute to drought resistance in stems. We will pair HRCT with scanning electron and light microscopy to characterize the early stages of infection at unprecedented resolution. This work will involve culturing of wood canker pathogens at discrete points after inoculation to determine the extent of spread within the grapevine xylem.


3.Progress Report:

This agreement was established in support of objective 3 of the in-house project, which is to develop sustainable water management practices for vineyards. The goal of this project is to examine the influence of drought stress on the progression of early stages of wood canker infection of grapevines. This agreement was recently established on 06/01/2012. We will utilize High Resolution Computed Tomography (a type of CAT scan; HRCT) to characterize the early stages of wood canker infection with unprecedented resolution on intact and excised woody portions of grapevines. By accomplishing these objectives, we will establish the foundation needed to develop detection techniques that utilize asymptomatic green tissues to confirm the presence of an infection within the woody portions of the vine. The pathogen does not reside in green tissues, but they are connected to the infected, woody tissue via a common vascular system and, thus, exhibit ‘signals’ of infection at the biochemical and molecular levels. Green tissues are much more convenient and less destructive samples to gather from the field compared to woody tissues. Also, green tissues are processed more rapidly in the diagnostic lab, as they do not contain as many inhibitory compounds (e.g., phenolics) as are found in wood, which necessitate lengthy extractions and confound nucleic acid-based detection tools. In essence, the non-colonized green tissues will serve as a bio-indicator of canker infection that is present lower in the woody portions of a grapevine. In subsequent funding cycles, we plan to use the non-colonized green tissues collected during the experiments outlined here to identify molecular markers using RNAseq in collaboration with University of Nevada, Reno. Funds for this project were only recently made available. Personnel needed to complete this work will be hired and will begin the work in October 2012. In anticipation of the arrival of this employee, the researchers leader worked with cooperator to inoculate vines and to complete preliminary high resolution computed tomography (HRCT) scans at the Advanced Light Source in Berkeley. These initial data look very promising in terms of fulfilling the goals of this work. Additional scans of inoculated plants will be performed during the research leader's upcoming beamtime in September, October and December 2012. Data generated from these scans will allow the new technician to hit the ground running with a HRCT datasets ready for analysis with AVISO software.


Last Modified: 12/19/2014
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