Estimating Inheritance Factors and Developing Cultivars for Tolerance to Charcoal Rot in Soybean

Authors: Smith, James - Rusty

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 5/17/2005
Publication Date: 1/15/2007
Citation: Smith, J.R. 2007. Estimating Inheritance Factors and Developing Cultivars for Tolerance to Charcoal Rot in Soybean. Book Chapter. 522-526.

Interpretive Summary: A fungal disease of soybean called charcoal rot can cause severe yield loss throughout the world. Although some soybean varieties appear to be tolerant to charcoal rot, many others are susceptible. The reasons for varietal tolerance or susceptibility are unknown. In addition, reliable methods to test for tolerance to charcoal rot are very labor intensive and time consuming, and thus have not been applied routinely to soybean breeding programs. Hence, little progress has been made to alleviate soybean yield loss caused by charcoal rot. The purpose of this research was to use improved testing procedures to determine the inheritance of tolerance to charcoal rot and to develop improved varieties with tolerance to charcoal rot. Genetic, breeding, and pathology methodologies are presented to accomplish the above goals.

Technical Abstract: Charcoal rot of soybean [Glycine max (L.) Merr.], caused by Macrophomina phaseolina (Tassi) Goidanich, occurs throughout the world, where it can cause severe yield losses. Although genotypic differences for susceptibility to charcoal rot are known, the causal genetic factors for such differences are unknown. The development of improved cultivars with tolerance to charcoal rot has been hampered by the lack of knowledge of pertinent inheritance factors and by the lack of suitable methodologies for assaying the large numbers of breeding lines typical of most soybean breeding programs. The purpose of this paper was to outline the necessary steps to determine the inheritance of tolerance to charcoal rot and to plan for the development of improved soybean cultivars with tolerance to charcoal rot. A case is made for the development of multiple early-generation populations for testing theories of qualitative and quantitative inheritance. Using such populations, as well as recombinant inbred lines, methods to estimate heritability, genetic gain from selection, linkage maps, and the identification of molecular markers linked to genetic factors affecting tolerance to charcoal rot are proposed. It is anticipated that improved assay methodologies will allow researchers to accurately determine the inheritance of tolerance to charcoal rot in soybean and to develop improved soybean cultivars with tolerance to charcoal rot. The knowledge gained and the technology transferred will help to alleviate production problems caused by charcoal rot.