Brief Summary of Minutes of Annual Meeting

1) Meeting brought to order by Chairman Sandy Pierson at 8:30 AM. Present: J.H. McBeath, P. Gay, L.S. Pierson III, J.O. Becker, J. Borneman, J.A. Menge, M. Stanghellini, N.W. Callan, G.S. Abawi, D.M. Weller, T. Paulitz. Absent: K. Subbarao, C. Bull, F. Martin, W. Chun, N. Goldberg, J.E. Loper, J. Parke, F. Crowe, P. Okubara, N. Grunwald, E. Riga. 2) Minutes from the previous technical meeting were discussed and approved. 3) W-1147 renewal. Administrative Advisor Don Cooksey reported that W-1147 had been approved for five years. The next renewal will be in 2007. 4) W-1147 Website. A website could be used to distribute state research reports and post a list of tested biocontrol agents. Several options for a W-1147 website were discussed. Don Cooksey will talk to Wesley Chun, and Sandy Pierson will talk to Ole Becker. 5) Meeting adjourned at 10:30 AM for a tour of MSU Plant Growth Center with Don Mathre. 6) Meeting resumed after lunch. 7) Membership. There was a discussion of increasing attendance and recruiting new members. It was suggested that we try to coordinate the annual meeting date with another scientific meeting. 8) Reports. All members must submit reports, whether attending the meeting or not. Don Cooksey instructed the committee to use the template that had been distributed and is available at http://www.escop.msstate.edu/archive/SAES422preparation.htm. The current Chair (Sandy Pierson) will incorporate all individual reports into the new annual report format. 9) Biocontrol Agent List. Members should send name of organism, pathogens controlled, usual host plant, and descriptive information to Sandy Pierson for eventual posting on a W-1147 website. 10) Meeting Locations. The 2004 meeting is to be a joint meeting with S-302 and NC-125. James Borneman will contact the other committees to determine the meeting arrangements. The 2005 meeting will be held in Portland, Oregon. 11) New Officers. 2004: Chairman, Nancy Callan; Secretary, James Borneman 2005: Chairman, James Borneman; Secretary, Tim Paulitz 12) Meeting adjourned at 6:00 PM, 25 October, 2003. Discussions continued over dinner. Submitted by Nancy W. Callan, Secretary

The complete annual report of accomplishments from W1147 for 2003 can be obtained from the Administrative Advisor. An abbreviated report follows. Goal 1: To identify and characterize new biological control agents, naturally suppressive soils, cultural practices, and organic amendments that provide control of diseases caused by soil borne plant pathogens. One of the challenges to improving biological control of soil borne plant diseases is to overcome the inconsistencies associated with host and pathogen complexity and diversity, the effects of competing microflora, and variations in soils and cultivation practices. The greatest strength of the regional research approach by members of W-1147 is the diverse expertise each member contributes. Since plant-pathogen systems are so varied, they must be tailored to each geographical area, crop variety, and pathogen. However, our collaborative approach can reveal similarities and common themes not otherwise noticeable. Members this year are working on 7 different plant pathogens, including bacterial, fungal and nematode pathogens. Current exciting results included the discovery of 23 potential biological control agents. A summary of this past years discoveries is given below. Intended outcome: The identification of new potential biological control agents. Milestone: Development of a new method for identifying suppressive organisms. Several W-1147 members are working to: (i) develop new experimental approaches for identifying microorganisms involved in pest suppressiveness in soil and, (ii) use this approach to identify bacteria and fungi involved in soil suppressiveness against several plant pathogens, including the plant-parasitic nematode Heterodera schachtii,and the fungus Phytophthora cinnamomi, the causal agent of avocado root rot. The hypothesis being tested is that the microorganisms responsible for disease suppression can be identified by correlating their population levels using molecular techniques with soil suppressiveness. This approach has four phases. The first phase is to create a series of samples exhibiting various levels of suppressiveness through manipulation of microbial community composition. In phase two, we utilize our newly developed, array-based method to identify microorganisms that correlate with suppressiveness. Phase three employs quantitative PCR to confirm the correlations between the microbial population trends and suppressiveness. In phase four, the candidate organisms are isolated and reintroduced to assess their abilities to produce suppressiveness. Results obtained this year demonstrated that this approach was successful in identifying organisms involved in H. schachtii suppressiveness. Milestone: Development of a real time fluorescent PCR assay specific for Aphanomyces euteiches. A. euteiches causes severe root rot of peas. Resistance is limited in commercial pea cultivars. Lack of progress in breeding for resistance may in part be due to limited discriminatory power of typical screening procedures, which rate disease severity using an integer scale. We developed a real time fluorescent PCR assay specific for A. euteiches. Milestone: Develop methods to estimate genetic diversity of pathogen populations in the field. When analyzing plant pathogen and microbial populations in the field, it is important to be able to estimate the level of genotypic diversity. The degree of variation for genotype and pathogenicity in a population of Aphanomyces euteiches within two growers fields with a history of Aphanomyces root rot was determined. We evaluated two hypotheses: (1) populations of A. euteiches are diverse genotypically and phenotypically within single fields, and (2) that populations of A. euteiches from different fields are well differentiated. Milestone: To measure the distribution and stability of naturally suppressive soils. A survey of California avocado groves is continuing to identify local groves, which have soils that are suppressive to Phytophthora cinnamomi. We are utilizing several experimental approaches to extract biological control agents from local suppressive soils. One of them is to identify bacteria and fungi from soil mixtures with varying degrees of suppressiveness. Molecular examinations of the microbial communities confirmed Galactomyces as a major component of the suppressive soil. A second approach is to characterize microorganisms spatially and temporally present in various stages of a field epidemic. Populations of P. cinnamomi appear to decline precipitously immediately behind the leading edge of the epidemic in some groves. Biocontrol fungi are being isolated from this region. We postulate that microorganisms, which fill a niche similar to that of the pathogen or that compete for chemical substrates important to the pathogen, such as root exudates, will be effective biological control agents. To identify such organisms, we have developed an in situ, culture-independent strategy to identify bacteria and fungi that rapidly grow in response to specified chemical substrates in environmental samples. Milestone:An additional approach to discover new biological control organisms is to identify suppressive organisms from sites where the pathogen has been around the longest. The rain forest of Papua New Guinea is thought to be the center of origin for P. cinnamomi. We have enlisted the aid of Bob Tombe, University of Goroka, Papua New Guinea, to cooperate with us and send samples every two months for the next two years. Unfortunately Dr. Tombe was robbed and lost his rented vehicle while collecting samples for us, so the cost and effort to get these samples has been great. We received only two new shipments of soil from New Guinea. Results from these shipments were rather disappointing with only a few soils showing suppressiveness to Phytophthora cinnamomi. These results were far less impressive than results we obtained last year. However, a group of these soils from the Mt. Kubor region of New Guinea gave exceptional suppressiveness. Phytophthora placed in these soils became vacuolated and died very quickly. Even chlamydospores were killed. Milestone: Determine the efficacy of biological control agents in the field. The efficacy of biocontrol agents was tested on both Sclerotinia sclerotiorum and S. minor at the Desert Research & Extension Center in El Centro, CA. Treatments evaluated were Plant Shield (Trichoderma harzianum), Companion (Bacillus subtilis), Contans (Coniothyrium minitans), and Rovral. None of the treatments including Rovral was effective against S. minor. These treatments were also duplicated in Yuma, AZ, and even at this site, all treatments failed. Incidence of lettuce drop caused by this species in different plots at El Centro varied between 60-80%. Similarly, of all the treatments against S. sclerotiorum, Contans provided almost complete control of lettuce drop. Less than 5% of the plants in plots treated with Contans were diseased. Studies are underway to compare the efficacy of Abamectin, a secondary product of Streptomyces avermitilis as a seed treatment against the root-knot and lesion nematodes Meloidogyne hapla and Pratylenchus penetrans, respectively. Milestone: The purpose of this work was to compare Rhizoctonia populations at different positions within the patch and at different soil depths and to see if patches would be maintained in the R. solani-infested cores over successive plantings in the greenhouse. At the first planting, activity of R. solani was higher in the center and inside edge, but after the second planting, there were no differences among the patch positions. Based on plant height, patches were maintained in only 6 out of 16 sets of cores. R. solani activity was similar at all soil depths from 2-20 cm. Evidence for suppression of Rhizoctonia in spring wheat after spring barley has also been documented in a 5 year rotation study at Ritzville. The area in patches in spring wheat following spring barley is less than half, compared to continuous spring wheat Maps also show that patches disappear and new ones appear on an annual basis. We will do further studies with this mapping data to see how many of the patches decline in a given year in each rotation. Milestone: Include analysis of the plant host for improving disease control. Potatoes (Solanum tuberosum) contain products termed osmotins, a family of proteins correlated with the plants survival against biotic and abiotic stresses. Osmotins have been implicated in broad-spectrum pathogen resistance as well as drought and cold tolerance. Although osmotin genes have been characterized from wild Solanum species, very little is known about osmotin genes from cultivated Solanum tuberosum. Sequence alignment revealed a range of 91-99% similarity to S. commersonii osmotin genes. A phylogenetic tree was generated for cultivar comparison based on osmotin gene amplified products. Milestone: Determine the effect of Brassica residue on the incidence of soil-borne diseases in chile. The primary objectives of this project were to compare disease incidence and overall yield of Phytophthora root rot, Verticillium wilt and Root-knot nematode in field plots treated with various Brassica crop residues. Goal 2: To understand how microbial populations and their gene expression are regulated by the biological (plants and microbes) and physical environment and how they influence disease. Intended outcome: Further understanding of the molecular basis of biological control mechanisms and the influence of the environment on the expression of these mechanisms. Milestone: Continue to elucidate the molecular basis of secondary metabolite production responsible for pathogen inhibition by Pseudomonas aureofaciens 30-84. Milestone: Delineate the phenazine biosynthetic pathway. Milestone: Characterize the molecular mechanisms by which T. atroviride controls plant pathogens. Milestone: Characterize the role of DAPG (Phloroglucinol) in control of Pythium spp. Milestone: Develop a technique to accurately quantify Pythium damage (root scanning with WinRhizo software). Milestone: Determine the effect of the addition of wild type and transgenic biocontrol strains on the indigenous rhizobacterial population. Milestone: Determine the host contribution to the process of root colonization. Milestone: Determine additional genes that contribute to rhizosphere success. Milestone: For the first time ever, the full genomic sequence of a biocontrol agent, Pseudomonas fluorescens Pf-5, was determined, in a collaborative project involving several W147 members (Loper, Pierson, and Thomashow). Milestone: Factors influencing the production of pyoluteorin by the biological control agent Pf-5 include autoinduction. Goal 3: To develop and implement biological control in agriculture. Intended outcome: To move basic research results into sustainable agriculture. Milestone: Utilize the bacterium Pseudomonas putida to control Phytophthora cinnamomi in the field. Milestone: The EcoSoils Bioject machine has been thoroughly tested and has been found to produce high quality biocontrol agent inoculum in the field and deliver it reliably in the irrigation water. Milestone: Determine the mechanism by which the cover crop Sudan grass reduces pathogen success. Milestone: Develop assessment methods for soil health. Milestone: Develop disease management strategy for the control of vine-decline of melons caused by the root-infecting fungus Monosporascus cannonballus. Milestone: Determine whether LCF (Liquid Compost Factor) enhanced chickpea germination in the field. Milestone: Pseudomonas corrugata is basically a weak pathogen of very little interest to plant pathologists. However, it has great potential as a biological control agent for fungal root diseases. Milestone: Reduction of stolon decay in Peppermint.