THE IMPACT OF MOLECULAR MARKER AND GENETIC MAP INFORMATION ON BREEDING AND SELECTION STRATEGIES

摘要

In the sugarcane variety development program conducted by SASRI, molecular markers have been used as breeding tools since 2002, aimed in particular at improving resistance to smut and the stalk borer Eldana saccharina. Currently, this activity is being expanded to identify and map markers contributing to yield components and sucrose content within the parent germplasm used in the breeding program. The availability of genetic maps of individuals making up the breeding population reveals the underlying genetic structure contained within it. The question then is, how to effectively use this information to improve breeding efficiency, while taking traditional breeding concerns based on quantitative genetic theory into account. Problems that must be addressed, among others, include the following: What is the level of selection pressure that can be placed on a small number of marker loci without negatively affecting genetic diversity within the breeding population, or drastically skewing the population structure? How should genotypes without marker information be effectively incorporated into the overall strategy, and should breeding populations be sub-divided? What are the physical constraints that may limit the wide scale use of markers and map information, and how can resources be optimised? How can these questions be addressed by either designed experiments or by simulation models? This paper seeks to address the issues that are faced in breeding programs when detailed genetic information on the breeding population is available.