Our goal is to develop a new method to detect trunk diseases by sampling asymptomatic leaves. We revealed a unique set of grape genes expressed in asymptomatic leaves in the early phase of infection, using Botryosphaeria dieback pathogen Neofusicoccum parvum as a model to study host responses to a trunk pathogen. Tests are in progress to confirm specificity of these grape genes to Neofusicoccum infection, in inoculations with other trunk pathogens, common foliar pathogens, and to rule out possible interactions with drought stress.
Link to presentation:Early Detection
Mizuho Nita, and Sabrina Hartley
Progress update on development of web and mobile diagnostic application that will enable growers to properly diagnose trunk vine diseases and in return help determine proper management practices for the specific trunk disease identified.
Link to the presentation: Development of web application of grapevine trunk diagnostic tool
Renaud 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”
Goal 2 – Accurate identification of trunk fungi
Activities – Allow for proper disease management and control practices
Results & Outputs – Developed a comprehensive DNA sequence database of trunk inhabiting fungi
Significant Outcomes & Impacts – Accurate species identification will lead to proper disease management practices.
Goal – Identify new commercial cultivars with resistance to the most aggressive causal agents of Panicle blight of pistachio.
Evaluated resistance in all susceptible tissues (green tissues: panicles & fruit, woody tissues: stem) with the three most aggressive pathogens (Botryosphaeria dothidea, Neofusicoccum mediterraneum, and Lasiodiplodia citricola), either alone or in combination. Inoculations were done on mature trees in an experimental orchard.
Results & Outputs
To identify resistant germplasm, stem inoculations are required. Inoculation of green tissues leads to blighted panicles and fruit. However, results were not different among cultivars and all three pathogen species colonized equally. In contrast, inoculation of stems lead to cankers of different lengths, depending on the cultivar and the pathogen.
Kerman, which makes up >90% of California pistachio acreage, showed an intermediate level of resistance, with cankers ranging from 5 to 20 cm. Even more resistant (i.e., with smaller cankers) were new cultivars Golden Hills, Lost Hills, and Randy. New cultivars Kalehghouchi, Joley, and Aria were most susceptible than Kerman. Among the pathogens, Lasiodiplodia citricola was the most aggressive species (i.e., caused the largest cankers) on all seven cultivars, including Kerman.
Significant Outcomes & Impacts
Several new cultivars – Golden Hills, Lost Hills – are more resistant than Kerman. The inoculation method we developed will be important for evaluating preventative fungicides, esp. given that even the most resistant cultivars still develop cankers.
Goal – Develop visual diagnostic aids for trunk diseases.
Activities—Create a web/mobile application and website for trunk disease diagnosis.
Results & Outputs
Developed beta-versions of logic and flow charts.
Significant Outcomes & Impacts
Accurate disease diagnosis will minimize losses by leading growers to proper management practices.
Link: Trunk Disease Management for Eastern grape growing regions
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.
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
For more movies, please click the link below:
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.
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.
Goal 1 – Develop a detection tool for spores of wood-canker pathogens (aka trunk pathogens), combined with new molecular markers for rapid identification.
Activities – Evaluated spore traps in young, apparently-healthy vineyards vs. mature, diseased vineyards.
Results & Outputs – Demonstrated that both young and mature vineyards are at similar risk of infection by spores of the same trunk pathogens.
Significant Outcomes & Impacts – Growers routinely forego preventative practices in young vineyards because trunk diseases are not a serious problem until year 8. Our results make it clear – disease prevention should be adopted in young vineyards.