BREAD: Molecular and Genomic Strategies to Engineer Durable and Sustainable Disease Resistance to Bacterial Blight of Cassava

University Of California-Berkeley, Berkeley CA

Investigators

Abstract

PI: Brian Staskawicz (University of California Berkeley) Co-PIs: Wilhelm Gruissem (ETH Zurich, Switzerland), Adriana Bernal (Universidad de Los Andes, Colombia) Cassava bacterial blight, incited by Xanthomonas axonopodis pv. manihotis (Xam) is a serious threat to cassava plants in several developing countries in both Africa and South America. This project will first focus on the genome characterization of Xam to sequence, annotate, and characterize the constellation of bacterial effector (virulence) proteins that are present in naturally occurring field isolates of this important bacterial pathogen. The ability to rapidly and inexpensively determine the genome sequence of natural field isolates of Xam will provide novel insights into the evolution of pathogen virulence and the allelic diversity of effector genes that occur in natural populations. The genome assemblies of Xam will be employed to identify new sources of disease resistance in wild populations of cassava plants. Previous work has demonstrated that the PthB effector is present in all strains of the pathogen and is essential for the pathogen to cause disease. Work in this project will engineer cassava plants to recognize the PthB protein to provide effective and durable disease resistance. Results from the project are expected to provide a durable source of resistance to this very important bacterial pathogen of cassava. In addition, the knowledge generated in this project will greatly benefit cassava researchers in both Africa and Latin America. The project will have a major impact in cassava breeding and will hence benefit smallholder agriculture in developing countries from Latin America, Africa and Asia. The collaboration between experts in genomics, plant-microbe interactions and cassava transformation with scientists who work on this important crop in developing regions will have synergistic effects in the deployment of new resistant varieties to this and other diseases. Furthermore, two Colombian graduate students will be trained under this project. The training of Colombian scientists in cutting edge technology at the Staskawicz and Gruissem laboratories will greatly benefit Colombian agricultural science. Access to project outcomes Genomic sequences of Xam will be made available at NCBI and at a dedicated project website that will be created for this project to both facilitate the sharing of results between the groups involved, and the prompt dissemination of reliable data for the research community. The project web site, which will be accessible from http://plantbio.berkeley.edu/~stask, will include a description of bioinformatic algorithms developed for the assembly and annotation of the genomes, information on the bacterial strains analyzed, and description of the constructs and cassava plants developed in the project. All of these resources will be made freely available to the research community.