RESEARCH-PGR: Discovery and Functional Characterization of Genes Regulating Plant Immunity in Perennial Crops

The human population is projected to grow to 9.6 billion by 2050, requiring a 50% increase in food and fiber production. A major constraint to this goal is crop losses due to microbial plant diseases which destroy approximately 15% of the world's total crop production every year. Advances in the science of plant disease control are needed to reduce crop losses to disease. Plant genomes encode thousands of genes involved in disease resistance, called the plant immune system. For some crops, modern science has made rapid progress in identifying disease resistance genes and using them in plant breeding, but for others such as long-lived tree crops, it is much more difficult to make rapid progress. This project will explore the plant immune system via a comprehensive study of the genes important for disease resistance to key pathogens of an important crop, cacao, which is the source of chocolate, and an important cash crop for millions of farmers in developing countries. The methods, tools and knowledge gained will be directly applicable to discovery of genes underlying important traits in other crops, especially trees and many perennial grasses. In addition to contributing to building a global partnership in reaching the goals of feeding a growing population sustainably, this project will involve students and young scientists in the US and in developing countries though international exchanges and collaborations.

This project will establish a new approach for use with perennial crop plants to identify candidate loci for disease resistance using a model tree crop, Theobroma cacao (the chocolate tree). Whole genome re-sequencing and transcriptome sequencing of a core collection of highly diverse cacao genotypes will provide the genetic information necessary to drive the discovery of genes critical for pathogen resistance. Functional analysis of these genes will test their role in resistance and set the stage for future translation of these basic findings to guiding more efficient breeding programs utilizing a wider array of genetic diversity. Importantly, the methods, tools, and knowledge gained will be directly applicable to discovery of genes underlying important traits in other crops, especially heterozygous perennials such as trees and many grasses which are not particularly amenable to approaches developed for the major annual crops such as corn and soybean. The basic evolutionary and functional principles that will be discovered can be generalized to most if not all crop plants. To promote and build genomics research capacity in developing countries and to promote inter-disciplinary cross-training the project will support scientific exchanges between project members and foreign collaborators, through postdoctoral, graduate and undergraduate student training at multiple institutions and will involve students from minority serving institutions. The results of this study will be made publicly available through electronic resources and publications.