ARS | Publication request: SNP-Based Improvement of a Microsatellite Marker Associated with Karnal Bunt Resistance in Wheat

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 23, 2005
Publication Date: May 18, 2006
Citation: Brooks, S.A., See, D.R., Brown Guedira, G.L. 2006. SNP-based improvement of a microsatellite marker associated with Karnal Bunt resistance in wheat. Crop Science. 46:1467-1470

Interpretive Summary: The purpose of the work presented in this manuscript is to describe a method for designing markers specifically for plant breeding programs. In applied plant breeding the majority of progeny derived from a specific cross are discarded while few lines are selected based upon desirable traits. Some traits that are difficult to score, have minor effects or are influenced by the environment can be a major obstacle for variety development. In these cases molecular markers are useful for definitive selection of ambiguous traits. In many cases markers are available from basic (theoretical) research where association of a marker(s) with a desirable trait has been described. However, these markers are not universally applied to solve problems in marker assisted breeding. In this manuscript we address this issue and offer a method to refine an existing marker to address the specific goals of marker assisted selection. Furthermore, we describe the utility of a single marker refined for selection of a disease resistance trait in wheat.

Technical Abstract: Marker assisted selection has become the technology of choice for introgressing important traits with indistinct phenotypes into agronomically elite varieties. The value of molecular markers is largely dependent upon their ability to meet the needs of plant breeders. In many cases published markers from basic research projects are not directly applicable to marker assisted plant breeding. Here we describe the conversion of a microsatellite marker known to have significant association with resistance to the fungal pathogen Tilletia indica in wheat. By sequencing the fragments amplified by the original marker we were able to design a new SNP based marker that selectively amplifies the fragment of interest. This new marker has many advantages over the original and was specifically designed to meet the needs of plant breeders. The design improves amplification consistency, reduces ambiguity and allows easy identification of heterozygous plants.