Understanding the principles of complex trait inheritance and genetic incompatibility

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This proposal intends to establish the basis for studying the inheritance patterns, frequency and phenotypic effects of accumulating quantitative trait loci (i.e. genome segments or QTL) that control three genetically complex traits in dry bean (Phaseolus vulgaris L.). The long-term objective of the program is to understand the role of deleterious alleles in the fitness and improvement of self-pollinated crop species, particularly their involvement in complex trait architecture and genetic compatibility. The short-term goal will be to develop multi-parent advanced generation inter-cross (MAGIC) populations. We will create three structured populations that contain multiple verifiable genomic segments maximized for recombination and multi-QTL introgression using disease resistance and drought tolerance as complex traits under study. White mold is a serious disease in dry bean, particularly in high-input irrigated production systems. In such situations, irrigation can potentially lead into higher white mold disease incidence. The first specific objective will develop knowledge on the genetic mechanisms of durable resistance to white mold, Sclerotinia sclerotiorum Lib. de Bary. In dry bean, intermittent and terminal drought stress events results in losses in productivity of over 60% worldwide. Dry bean growing regions of Canada often require supplemental irrigation, particularly the western provinces. The projections for the 2016-2035 period predict a decrease in precipitation of up to 10%. The second objective will involve developing populations for understanding the genetics behind drought stress tolerance. New technologies promise to enable the guided introgression of multiple independent QTL responsible for enhanced white mold resistance or drought tolerance. We hypothesize that: i) large arrays of genetic markers derived from whole genome sequences are capable of informing rate of introgression of multiple interacting QTL of interest into structured populations; ii) field sensors can increase the precision in measuring and dissecting traits of interest with sufficient throughput while minimizing error and maximize selection accuracy in accumulating multiple QTL; iii) directed recombination and selection for individuals with multiple interacting QTL can be predicted using adaptive statistical models specific to QTL of interest. The results from this program will create a platform for improving complex traits in pulse crops by developing single nucleotide polymorphism (SNP) arrays and high-throughput phenotyping tools in the field. Canadian plant breeding programs will benefit significantly from the results obtained. Specifically, the understanding of complex genetic structure will enable Canadian pulse breeding programs to design strategies to accelerate the rate of genetic gain. More importantly, a breakthrough into the principles governing complex trait inheritance will be revealed, impacting the rate of genetic gain in self-pollinated crops.