Abstract

Charcoal rot (CR) disease caused by Macrophomina phaseolina is responsible for significant yield losses in soybean production. It is ranked among the top 10 soybean diseases in the United States with an average annual yield loss of one million tons. CR is a soil- and seed-borne polyphagous fungus. The abundant production of minute black microsclerotia causes the infected plant tissues to blacken, and therefore, the disease is known as charcoal rot. Charcoal rot management strategies in soybean have not been overly effective or widely adopted and have provided limited control, leaving genetic resistance as one of the most feasible and sustainable methods to manage CR. Complete resistance to M. phaseolina is not reported in any of the 500 plant species it infects, but identification of partial resistance has been reported in soybean. Breeding for resistance is difficult because most diseases are quantitatively inherited and controlled by multiple genes. CR is a greater concern in the southern United States due to frequent hot and dry conditions that tend to occur during important soybean developmental growth stages. However, the identification of CR in soybean growing regions in the northern latitudes is on the rise and more pronounced in Iowa’s warm and dry growing seasons. The objectives of this study were to identify new sources of resistance to CR in a collection of 459 diverse plant introductions from the USDA Soybean Germplasm Core Collection. Field and greenhouse screenings, and genome-wide association studies (GWAS) were used to identify candidate genes and associated molecular markers. These genes and markers can be used in subsequent breeding applications to develop resistant cultivars for the northern growing region. This field study took place in the 2015 and 2016 growing seasons at the Muscatine Island Research Farm.

How to Cite:

Scott, B. & Singh, A. K., (2018) “Breeding Charcoal Rot Resistance into Soybeans”, Iowa State University Research and Demonstration Farms Progress Reports 2017(1).