2014 Board Meeting -Renaud Travadon & Kendra Baumgartner

BaumgartnerTravadon_GrapeGermplasm.picRenaud Travadon & Kendra Baumgartner

Developing rapid grapevine screening process to identify wine and table grape cultivars for resistance to Eutypa Dieback based on foliar and woody symptoms. Future efforts towards comparing gene expression profile between previously characterized resistance and susceptible cultivars.

Based on previously discovered Phomopsis resistant genes, determine if woody tissue resistant genes can be linked to green tissue symptom expression.

Determine how anatomical and chemical differences effect Botryosphaeria resistance levels in 7 table grape cultivars.

Link to the presentation: “Baumgartner and Travadon presentation for the board meeting 2014”

 

Host-based molecular markers for early detection of infection

  • Goal– To determine if host-based molecular markers are unique to a particular pathogen
  • Activities – Identification of which pathogens are present in grapevine wood

Host marker 1Host marker 2Water stress4 Results and Outputs – Utilize qPCR to detect differential expression of target genes Water stress 6Significant Outcomes & Impacts – Identification of which pathogens are present in nursery stock grapevine wood. Eliminate contaminated stocks that would otherwise be used for propagation.

Identification of new anatomical and biological resistance markers

Goal – Identify new anatomical and biochemical markers of resistance in grapevine wood.

Activities – Characterize changes in the wood that correspond to resistance to Eutypa dieback, using cultivars with known resistance/tolerance: Merlot (resistant), Cabernet Sauvignon (intermediate), and Thompson seedless (susceptible).

3.2

Results & Outputs – Identified differences in cell wall and xylem characteristics. Susceptible tablegrape Thompson seedless had low lignin and high glucan in its cell walls, whereas resistant winegrape Merlot had high lignin and low glucan (Cabernet Sauvignon was intermediate). Xylem vessel diameter also differed between these two cultivars; Thompson seedless had the largest vessels and Merlot had the smallest.

Significant Outcomes & Impacts – These markers of Eutypa resistance will compliment the detached-cane screening method, to provide additional measures of resistance. This is important because we are evaluating genetically-diverse germplasm, which may exhibit different modes of resistance. These markers are now being evaluated for the other trunk diseases (Botryosphaeria dieback, Esca, Phomopsis dieback), along with the detached-cane method of screening.

Development of Screening Technique

Goal – Develop a rapid and reliable screening technique for resistant grape germplasm.

Activities – Compared screening methods for resistance to Eutypa dieback among nine genetically-diverse cultivars.

3.1

Results & Outputs
Merlot and Primitivo were most resistant to Eutypa dieback, based on both methods (hardwood cuttings and detached canes). However, the detached-cane method – a rapid alternative that takes only 5 weeks – differentiated cultivars similarly to the hardwood-cutting method, which is the standard in most labs.

The susceptible control, table-grape cultivar Thompson seedless, was ‘beat’ by an even more susceptible table grape cultivar, Husseine. Fortunately, this is not a commercial table grape, but it can serve as a new susceptible control in our studies.

Significant Outcomes & Impacts
The detached-cane method will serve as a phenotyping assay for use with materials from VitisGen and other grape breeding projects. In this way, our SCRI project builds on other SCRI projects that have already completed major genotyping efforts.

Develop a detection tool for the early stage of infection

Goal – Develop a detection tool for the early stage of infection, to quickly identify infected nursery stock, and as a study tool for field-testing new pruning-wound protectants.

Activities – Defined the timing and characteristics of the early stage of infection by the Botryosphaeria dieback pathogen Neofusicoccum parvum, based on spread of the infection and anatomic changes in the trunk, and differential gene expression in the leaves.

1.3b

Use of High Resolution Computed Tomography

HRCT of grapevine at 2weeks after infection


HRCT of uninfected grapevine

Our focus in 2013-2014 was on Neofusicoccum parvum, which attacks grape, almond,
and pistachio. As the canker developed, anatomical responses in the woody stems of
potted grapes were examined by light microscopy and High Resolution Computed
Tomography (HRCT). Comparisons of inoculated – wounded plants (IW) vs. non-
inoculated – wounded plants (NIW) showed the main differences at 2 MPI. IW plants
were characterized by xylem vessels filled with gels, in stems of intact plants examined
by HRCT.
For more movies, please click the link below:
http://www.youtube.com/channel/UC7YEU_hMmKB9IEsoAUkbljg/feed

Results & Outputs – Identified a set of eight grapevine genes (aka ‘molecular signature’) expressed in leaves during the early stage of infection from 0.5 to 1.5 months post-inoculation (MPI). For e.g., genes VIT_00s1455g00010 (dark bars) and VIT_01s0026g02710 (white bars) are highly expressed in inoculated plants, compared to the non-inoculated control plants.
1.4
Significant Outcomes & Impacts – Demonstrated ‘Proof of concept’, that the early stage of infection in the stem is detectable in asymptomatic leaves. This was first in a series of experiments, the next of which will confirm specificity of the molecular signature for possible interactive effects with drought stress and other trunk pathogens.