Sequence-Based Marker Assisted Selection in Wheat

Abstract

Wheat improvement has traditionally been conducted by relying on arti­ficial crossing of suitable parental lines followed by selection of the best genetic combinations. At the same time wheat genetic resources have been characterized and exploited with the aim of continuously improving target traits. Over this solid framework, innovations from emerging research disciplines have been progres­sively added over time: cytogenetics, quantitative genetics, chromosome engineer­ing, mutagenesis, molecular biology and, most recently, comparative, structural, and functional genomics with all the related -omics platforms. Nowadays, the inte­gration of these disciplines coupled with their spectacular technical advances made possible by the sequencing of the entire wheat genome, has ushered us in a new breeding paradigm on how to best leverage the functional variability of genetic stocks and germplasm collections. Molecular techniques first impacted wheat genetics and breeding in the 1980s with the development of restriction fragment length polymorphism (RFLP)-based approaches. Since then, steady progress in sequence-based, marker-assisted selection now allows for an unprecedently accu­rate ‘breeding by design’ of wheat, progressing further up to the pangenome-based level. This chapter provides an overview of the technologies of the ‘circular genom­ics era’ which allow breeders to better characterize and more effectively leverage the huge and largely untapped natural variability present in the Triticeae gene pool, particularly at the tetraploid level, and its closest diploid and polyploid ances­tors and relatives.