YIA-PGR: Genomics of Rice Susceptibility to Bacterial Diseases

Iowa State University, Ames IA

Investigators

Abstract

Bacterial diseases cause significant losses in many crops, and control measures often are limited or unavailable. The majority arise from invasion of the vascular system or colonization of the tissue between the veins (the parenchyma). The major classes of molecular tools that enable bacteria to thrive inside plants are beginning to be understood, but little is known about the functions within the plant of most of these tools. Less still is known about the plant signals and targets that render plants susceptible. Virtually nothing is known of the basis for tissue specificity. An understanding of the pathogen and host traits that create opportunities for microbes to exploit different plant tissues is an important goal. It will advance our fundamental understanding of plant biology and support innovative efforts to develop strategies to alter plant susceptibility or block pathogen virulence This five-year functional genomics project will 1) identify plant genes differentially expressed in response to two closely related pathogens of the same host that cause different, representative types of disease; 2) characterize genetic differences between these pathogens which likely play a role; and 3) identify plant genes that affect susceptibility or tissue specificity to the pathogens. The project is expected to yield key plant molecular targets and signals required for susceptibility and tissue specificity, and key proteins used by bacteria to infect plants in different ways. Rice (Oryza sativa), an important crop and a model species, will be used for these studies. Bacterial leaf blight (vascular) and bacterial leaf streak (parenchymal) will be examined. These diseases are caused by the two subspecies of Xanthomonas oryzae, pathovar oryzae and pathovar oryzicola, respectively. Both diseases are threats to US agriculture. They are also excellent models for the two most common ways bacteria cause disease in plants. The project will have the following broader impacts. It will integrate research and education by providing training and teaching experience for graduate students and postdoctoral researchers, and a two-week genomics module for high school biology students. The project will foster increased participation in science for underrepresented groups through summer internships for undergraduate women and minorities. The project will produce versatile molecular resources that will be useful in many different aspects of rice (and other cereal) biology and in plant bacteriology. In addition to publication for the scientific community, results will be disseminated to the public through the educational activities of the project, a project website, and other outreach efforts. Deliverables Data will be available online at <a href=www.public.iastate.edu/~ajbog> www.public.iastate.edu/~ajbog </a>. Clones, and seed from identified susceptibility mutants will be provided by Bogdanove on request on a cost-return basis. An important goal of the project is to construct Gateway (Invitrogen) cDNA libraries of rice undergoing infection by each pathogen, Gateway libraries of pathogen type III effector genes, and new compatible vectors for expression in pathogenic gram-negative bacteria. The Gateway system allows easy transfer of clones, in-frame and en masse without loss of representation, to a wide range of expression vectors. The Gateway rice cDNA library will be provided by Bogdanove <a href=mailto:ajbog@iastate.edu> ajbog@iastate.edu </a> or a third party distributor such as the ATCC on a cost-return basis. The Gateway Xanthomonas effector gene libraries and new destination vectors will be provided by Bogdanove on a cost-return basis.