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Chantal McCabe


Corn Insect & Crop Genetics Research Unit


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716 Farmhouse Lane
2209 Agronomy Hall
Iowa State University
Ames, Iowa 50011-4014



Research Interests:

Crop damage from pests and pathogens results in a loss of over $60 billion in the United States each year. Improving crop yields is critical to food security. My primary research interests are identifying and understanding resistance to biotic and abiotic stress. My work focuses on resistance to the soybean disease brown stem rot (BSR). BSR, caused by the soil borne fungal pathogen Phialophora gregata, is responsible for a yield loss of 13.6 million bushels annually in the US. My experiments focus on characterization of the genetic and genomic architecture of the three BSR resistance loci (Rbs1, Rbs2, and Rbs3) and generating molecular markers to improve BSR phenotyping and breeding efficiency. My research combines classical breeding, molecular genetics and genomics, while ensuring the molecular findings are applicable and economical for use by plant breeders.

Aims: Leverage genetics, breeding, RNA-seq, and gene silencing to unravel the complexity of resistance genes and gene networks in the Rbs locus and allow for candidate gene identification.

Background: Understanding genetic mechanisms underlying resistance is crucial in breeding for resistance to P. gregata. Phenotyping for BSR is difficult and time consuming requiring multiple destructive phenotyping measurements 5 to 6 weeks after infection, hindering progress in identifying and characterizing resistance loci necessary for marker assisted breeding. Further, traditional genetic studies characterizing resistance have provided conflicting results from single candidate R-genes to complex multigenic traits. In order for breeders to efficiently develop and identify cultivars with BSR resistance and avoid difficulties associated with BSR phenotyping, molecular markers near the candidate resistance gene(s) need to be identified. Further, downstream defense gene networks, regulated by transcription factors, could be mined to identify genes that provide or enhance resistance to multiple pathogens using traditional breeding or transformation technologies.

Approach: Defense gene networks and candidate resistance genes are identified using a suite of genomics tools including RNA-seq. Genes important in resistance are further characterized using virus induced gene silencing (VIGS).

Outcomes:  My research uses novel molecular approaches to identify and characterize soybean resistance genes in addition to developing molecular markers for use in breeding. These results will increase the efficiency of identifying and developing cultivars with one or more BSR resistance genes. Application of these results will reduce yield loss due to BSR in soybean, a loss of 13.6 million bushels annually in the US. These findings present new avenues for future soybean/P. gregata research and new methodical approaches that could have broad implications for other diseases and abiotic stressors affecting soybean and other crops.