Diagnostic DNA markers for quality traits in wheat

The mechanisms underlying some quality traits in wheat are now understood. Examples include the role of high and low molecular weight glutenins in contributing to strength and extensibility of wheat doughs, puroindolines that affect grain texture, and variation in granule-bound starch synthase that produces starches with altered amylose content and physical properties. This knowledge, coupled with the availability of the DNA sequences of various alleles of the genes encoding these proteins and the wide application of the polymerase chain reaction, has enabled the design of diagnostic DNA markers for these quality traits. Such markers are now being used by wheat breeders to select lines with the required quality attributes, without the need for the direct measurement of those traits in early generation screening. DNA markers may be implemented on leaf tissue from individual plants, for a number of independent traits, with results that are independent of environmental variation. The use of a common platform for all marker assays and the potential for multiplexing or parallel analysis of many different markers will further increase the efficiency and speed of the development of improved cultivars in the future. This review provides an overview of diagnostic DNA markers that are currently available for the selection of quality traits in wheat.