New approaches to the control of bacterial wilt in (Pseudomonas solanacearum) in tomato and other vegetable crop plants

• Lembung Experimental Horticultural Research Institute, Indonesia
• University of the Philippines at Los Banos, Philippines
• Bogor Research Institute for Food Crops Biotechnology, Indonesia

Solanaceous vegetable crops, pulses and fruit crops are important sources of food nutrients (especially vitamins A and D) for the growing populations of Southeast Asia. However, bacterial wiltcaused by Pseudomonas solanacearumis a major constraint to their production, with losses sometimes reaching 5070%. While breeding for crop resistance using traditional methods can sometimes minimise damage, new approaches are urgently needed.
In this project, research groups at Monash, Adelaide and Queensland Universities will collaborate with colleagues in a number of Asian centres. The team will apply developments in molecular genetic techniques and knowledge of bacterial wilt disease to provide a strain-classification and virulence-identification scheme that will be of immediate value to Asian agricultural scientists. The Australian researchers are well equipped to lead the project. They have studied bacterial wilt for many years, have a major centre for Pseudomonas genetic research at Monash University, and are already experienced in interacting with developing countries to solve agricultural problems.
The project will follow three main lines:
. Plant pathologists and plant breeders from Southeast Asian countries will be trained in plant and microbial molecular biology in Australia. The training will come through participation in existing research programs at the three Australian institutions aimed at developing molecular genetic techniques for P. solanacearum strain identification. The tools and techniques acquired will be applied in their home countries, with the Collaborative Network for Vegetable Research and Development in Asia (AVNET) assisting in the dissemination of information;
. The information gained from the research programs will be used to devise novel strategies for breeding resistant crop plants; and
. Additional short training coursesmaster classes' of 2-3 weekswill be run each year for agricultural scientists in areas of Southeast Asia where bacterial wilt is a particular problem.
Short-term (24 years) objectives are to:
. continue development of genetic techniques for P. solanacearum strain identification;
. improve strain classification;
. do field trials to aid in developing resistant cultivars;
. identify, clone and characterise genes associated with disease pathogenesis; and
. interact with the Asian Vegetable Research and Development Centre (AVRDC), Taiwan, in their breeding program for tomato resistance, and disseminate the information by AVNET (which is organised by AVRDC).

Longer-term objectives (3-6 years) are to:
. characterise the regulation of genes related to bacterial pathogenicity and identify their interaction with corresponding genes in various hosts;
. identify the genes required for bacterium-host interaction that are homologous to well-characterised genes from other plant pathogens;
. use this information to identify host resistance genes from cultivars established by conventional breeding; and
. combine the understanding gained of bacterial virulence genes and host resistance genes to develop strategies for disease control that are applicable to a variety of host plants.
Monash University will coordinate the project. Work on molecular classification of strains, identification of virulence genes and laboratory training of Asian research staff will be done at Monash and Adelaide Universities. Queensland University will collaborate with developing country institutions in the selection of resistant breeding lines and cultivars and compare existing strain classification procedures with molecular classifications. Queensland University will also conduct training courses for Asian research staff, and, with Adelaide University, participate in plant biotechnology master classes.
AVRDC will coordinate the testing of transgenic plants and genetically altered bacterial strains in the region, and test, package and disseminate the new technologies to develop effective disease-management strategies. The University of the Philippines will identify virulence genes, and test and use new breeding procedures for bacterial wilt resistance in tomatoes. The Plant Biotechnology Centre in Bogor, Indonesia, will field test new molecular identification procedures.
This project will have a widespread impact on control of bacterial wilt in many countries, including Australia.