Location: Crops Pathology and Genetics Research2013 Annual Report
1a. Objectives (from AD-416):
Utilize high resolution computed tomography to elucidate anatomical and physiological characters of grapevine rootstocks associated with biotic and abiotic stress tolerance
1b. Approach (from AD-416):
We will utilize High Resolution Computed Tomography (HRCT- a type of CAT scan) in combination with light and scanning electron microscopy to complete the project objective. Live vines and excised woody stems and roots will be scanned with HRCT at the Advanced Light Source (ALS) facility at Lawrence Berkeley National Lab using beamline 8.3.2. Resultant datasets will be analyzed at ALS and in the McElrone and Walker labs using AVISO software and a powerful PC dedicated to this work. We will first compare the vascular anatomy of grapevine varieties that exhibit Pierces’s Disease (PD) susceptibility, tolerance, and resistance. Accessions of Vitis girdiana and V. arizonica from ARS scientist's collection from the southwestern US will be used for this purpose and will be compared to Lenoir and Blanc du Bois varieties exhibiting PD resistance in TX growing regions. ARS scientist and colleagues recently used HRCT scans of the grapevine vascular system to identify previously unknown structures in the vascular system that have an impact on the plant's ability to prevent pathogen and embolism spread. Examining the internal progression (or lack thereof) of disease development in susceptible, resistant, and tolerant cultivars will provide significant insights into potential breeding targets and possible management strategies. The post doc also will be involved in related efforts to explore how different grapevine accessions/rootstocks respond to drought with specific focus on utilizing HRCT to visualize embolism spread and repair among the plant materials. During the funding period, the post doc will also conduct trial runs to test whether HRCT is a viable technique for studying root pests/pathogens in live, intact plants. Target patho-systems could include: root knot and lesion nematodes, trunk canker pathogens, Agrobacterium and Phytophthora.
3. Progress Report:
This project 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 the project is to utilize high resolution computed tomography to elucidate anatomical and physiological characters of grapevine rootstocks associated with biotic and abiotic stress tolerance. Scientists interviewed candidates for the open research associate position and hired an excellent plant water relations expert. Based on previous employment obligations, the research associate start date was pushed back to March of 2013. Since starting the position, the associate has been trained (including radiation safety training) on use of the High Resolution Computed Tomography (HRCT) position at the Advanced Light Source at Lawrence Berkeley National Lab, and subsequent scan analysis and data processing. He is currently working to become proficient in the use of AVISO software needed to process the HRCT datasets. Our recent set of scans completed during June and July of 2013 involved the following samples: 1) continuation of rootstock parent material evaluation to assess xylem cavitation resistance and embolism repair ability of 5 rootstocks; 2) scans of nematode-infested nutsedge tubers to determine if HRCT can be used for non-invasive detection technique; and 3) anatomical scans at 20X magnification (~600nm resolution) of grapevine stems that differ in Pierce’s Disease resistance. Data processing for these datasets are well underway and additional greenhouse and lab based work has commenced to compliment the HRCT-based experiments. Additional scans will be performed in the late Fall 2013 to compliment and expand existing datasets. The research team is making excellent progress towards the completion of the project goals.