Gene Pyramiding and Multiple Character Breeding

Plant breeders are often interested in improving several quantitative traits including yield, quality, and resistance to both biotic and abiotic stresses simultaneously. However, breeding for multiple traits together is challenging and largely depends on the choice of germplasm, and the genetics and genetic relationships among the traits under selection. Both conventional and molecular breeding approaches have been used to breed for multiple traits simultaneously. Several selection schemes including independent culling levels, tandem selection, and index selection have been developed and used to improve and integrate traits simultaneously. Of these, selection index was preferred in the past and has been used to improve the overall genotypic performance based simultaneously on several quantitative traits, even for traits with unfavorable associations. With the recent development and advancement in molecular marker technologies, molecular breeding has become preferred for targeted breeding and product development. Molecular breeding technologies including marker-assisted selection, marker-assisted backcrossing, marker-assisted recurrent selection, gene pyramiding, marker-assisted backcross gene pyramiding, and genomic selection have been used to introgress single or multiple genes. Multiple trait selection using selection indices based on information from both phenotypes and markers distributed across the whole genome has recently been practiced in various crops. Multiple trait selection is a realistic approach that can be exploited in lentil breeding programs to simultaneously improve multiple traits. In this chapter, we discuss various conventional and molecular approaches to breeding, improving, and integrating multiple traits into a single genetic background with relevance to lentil crops.