Grant Information
| Knowledge Area | Subject of Investigation | Field of Science | Percent |
|---|---|---|---|
| 212 - Pathogens and Nematodes Affecting Plants | 4010 - Bacteria | 1100 - Bacteriology | 40% |
| 216 - Integrated Pest Management Systems | 2410 - Cross-commodity research--multiple crops | 1100 - Bacteriology | 40% |
| 903 - Communication, Education, and Information Delivery | 6010 - Individuals (as workers, consumers, members of society) | 3030 - Information and communication | 20% |
Bacterial pathogens pose high risks to tropical agriculture worldwide and enter Hawaii undetected mostly as latent infections in imported agricultural commodities. Vector-borne bacteria, such as the Candidatus Liberibacter species that cause huanglongbing (HLB), and Xyllela fastidiosa, which causes citrus variegated chlorosis and bacterial leaf scorch of coffee, are imminent threats to Hawaii. HLB is associated with Ca Liberibacter bacteria vectored by the Asian citrus psyllid (ACP) or, in some cases, a phytoplasma. Xyllela fastidiosa-associated diseases are spread by the glassy-winged sharpshooter (GWS). Both GWS and ACP are now widespread in Hawaii and Florida, but surveys have been severely hampered in Hawaii by absence of a local detection program for bacteria of high consequence. In addition, other high risk bacterial pathogens in the genera Clavibacter, Erwinia, Pectobacterium, Dickeya, Ralstonia, Pseudomonas, Acidovorax, and Xanthomonas limit productivity in tropical agriculture. To reduce vulnerability and mitigate risk to these and other destructive bacterial pests of consequence, we must have the capabilities to detect, identify and impede their introduction and spread. Outcomes and impacts: 1) Rapid and reliable detection assays for bacterial pests of consequence that services the Pacific Islands, Florida, and the Caribbean basin will result in faster response times for regulatory action, containment and eradication, and increased reliability of export/import inspections; 2) Increased likelihood of early detection of bacterial pests of consequence reduces turn-around time and encourages sample submission through accessible portals; 3)Current diagnostic sample submission process will be improved for the Pacific Islands, Florida, and the Caribbean basin; 4) Shipping costs will be reduced due to local processing and diagnosis of samples; 5) Survey coverage will be expanded through coordination of activities with UH researchers, HDOA, APHIS, U.S. -Affiliated Pacific Island, Florida, and Caribbean basin collaborators, stakeholders, and the public; 6) Knowledge about distribution of bacterial pests of consequence in Hawaii, the Pacific Islands, Florida, and the Caribbean basin will be expanded; 7) Stakeholder will be made aware of bacterial pests of consequence and their spread, 8) Public and stakeholder participation in the free sample submission program greatly expands the survey coverage, 9) Research results will enable our future submissions to AFRI-supported "Management of plant bacterial diseases or plant insect pests" (FY2012) programs and others; 10) We will provide access to critically- needed local screening procedures for germplasm in Hawaii; 11) The survey and distribution results will permit evaluation of new germplasm expansion opportunities.
To reduce vulnerability and mitigate risk to these and other destructive bacterial pests of consequence. Specific objectives are to
Outputs: Research and extension publications on diseases and new methodologies for rapid and efficient detection and diagnoses of bacterial pests of consequence.
Bacterial strains and vectors will be isolated and identified. Nurseries that import plants from foreign countries and/or export to the continental U.S. will be surveyed for bacterial pathogens. Focusing on soft rotting bacteria and HLB. Pathogens will be characterized using serological analyses and genomic analysis. Robust and rapid field procedures will be developed combining immunodiagnostic and DNA-based assays. Field-tested protocols will be developed and verified for soft rot bacterial pathogens. Diagnostic devices will be evaluated and optimized for field use, employing several possible formats depending on the specific application of the diagnostic assay. Molecular detection assays for will be used for HLB. Sample collection procedures will emphasize prevention of cross-contamination and preservation of sample quality. Handling of HLB samples will follow established procedures from APHIS's HLB manual. Bacterial strains will be characterized. More strains will be added to the existing identification framework so that stronger inferences can be made with the other parameters. The current database consisting of both phenotypic and genomic characteristics of each strain will be amplified during the course of this project so that significant groups can be identified. A Survey of nonvectored bacteria will be undertaken. The locations from samples collected through the Florida Extension Plant Diagnostic Clinic at the Tropical Research & Education Center, the diagnostic clinic at the University of Puerto Rico, Juana Diaz, and the Agricultural Diagnostic Service Center (ADSC) at UH will be complied. Nurseries that import plants from foreign countries and/or export to the continental U.S. will be surveyed for bacterial pathogens. Surveys of high risk areas with citrus, coffee, key alternate hosts, and vectors will be conducted. Diagnostic samples from within the state will be submitted to the HLB Detection Program by the public and stakeholders through the ADSC portals established at the Cooperative Extension offices located throughout the state. The ADSC is a National Plant Diagnostic Network participating facility. We have formed a cooperative agreement with HDOA, APHIS, and our collaborators in the Pacific Islands to process samples collected during their HLB surveys. We have also formed a cooperative agreement with citrus growers throughout the state. They have agreed to submit samples from their citrus trees to the HLB Detection Program. Rapid turn-around and reliability will be the highest priority of our bacterial pests of consequence detection program. An extension and education component is integrated into the project. Posters, flyers, presentations, face-to-face contacts, and websites with linkages to other sources of HLB and other bacterial information, to grower groups, and to CTAHR, APHIS and HDOA will be developed. The media formats described above will be used in the formal and extension education venues.
Target Audience
Researchers and regulators at USDA-APHIS, diagnostic companies, corn seed producers, International Seed Testing Association, plant pathologists, field inspectors, basic researchers in plant pathology and molecular diagnostics.
Changes / Problems
The project was initially designed to detect and characterize only procaryotic pathogens, including fastidious bacteria. During the last reporting period surveys for other plant pathogens were expanded to include post-harvest diseases of tomato due to the needs and local interests of tomato growers. An island-wide survey was conducted on Oahu to determine the most prevalent bacterial and fungal pathogens associated with decayed fruit. We identified 70 different isolates of fungi. Botrytis cinerea and Pectobacterium carotovorum were the most prevalent plant pathogens associated with post-harvest diseases of tomato on Oahu. Further work is underway to investigate cost-effective control measures using natural products.
Training & Professional Development
Drs. Anne Alvarez and Diane Sether initiated this project for detection and characterization of bacterial plant pathogens. For bacterial diagnostics, students and technicians received training in bacterial characterization. A two week training session for a technician from a major seed company was also provided. The technician became familiar with physiological, cultural, and molecular tests for known seed-borne pathogens of maize. The training sessions and all of the local tests on HLB were later handled by M. Melzer with the help of research assistants, Asoka de Silva and Tomie Vowell. Two University of Hawaii (UH) researchers successfully completed the huanglongbing (HLB) training and detection course conducted at the USDA Center for Plant Health, Science and Technology laboratories in Beltsville, MD. An HLB detection center has been established at UH and inspected by the USDA's National Plant Pathogen Laboratory Accreditation Program. We are currently awaiting an HLB Proficiency Test Panel to complete the accreditation process. Federal and State of Hawaii permits have been obtained for intrastate movement of suspect HLB samples, as well as importation of samples originating from US Territories and Possessions in the Pacific. We have agreements with the Hawaii Department of Agriculture (HDOA) and the USDA's Cooperative Agricultural Pest Survey program to assay citrus samples and Asian citrus psyllids for HLB. HLB Training Sessions are currently underway at state and federal agricultural inspection stations across Hawaii, and have been well-received by participants. This 90 min training includes the background and importance of the disease, symptom recognition, how to perform an iodine-based field assay on suspect samples, how to submit samples and interpret the results, and a symptom quiz. Seven training sessions were conducted in: Honolulu (3 sessions), Hilo (1), Kailua-Kona (2), and Kahului (1), with additional training sessions scheduled for Lihue (1) and Honolulu (3); 81 participants have taken part in this training. Participants included Agriculture Inspectors with HDOA (49 participants), USDA Plant Protection and Quarantine Inspectors (11), Extension Agents with UH's Cooperative Extension Service (11), Customs and Border Patrol (6), and other citrus industry stakeholders (5). An evaluation form was completed by participants of the first training session to suggest ways to improve future training sessions. Fifteen forms were returned and suggestions were incorporated. The average overall rating of the session was 9.5/10 by the participants who returned forms. A lecture and laboratory in the Fall 2011 Plant Virology class (PEPS 630) at the University of Hawaii were dedicated to HLB. Graduate students were educated on the background of the disease and detection of the bacteria during lecture, and successfully performed the HLB detection assay during the laboratory period. Bacterial diseases of high consequence, including Liberibacter asiaticus, Xylella fastidiosa, Spiroplasma citri, and other non-fastidious bacterial pathogens with significant impacts on tropical and subtropical crops were discussed in depth in a graduate level course in Plant-Bacterial Interactions (PEPS 646) in Fall semesters 2012 and 2014. A new hands-on lecture laboratory course designed to increase the diagnostic capabilities of graduate students was taught for the first time in Spring 2016. Students received training in characterization and new methods of phenotypic and molecular identification of bacterial pathogens.
Dissemination Streams
Results have been disseminated through talks at national meetings, conferences, training sessions, fliers and guidelines, reports to USDA-ARS and USDA APHIS, conference calls, graduate classes, lecture and hands-on exercises in the plant pathology laboratory, and seminars.
Next Reporting Steps
Nothing Reported