Employment of wheat-rye translocation in wheat improvement and broadening its genetic basis

Hexaploid common wheat (2n = 6x = 42, Triticum aestivum L.) is one of the most widely cultivated crops and numerous attempts to improve the genetic constituent for superior traits have been conducted. Some of the rye (Secale cereale L.) chromosomes, especially the short arm of rye chromosome 1 (1RS) contain several disease resistance genes and have been introgressed into the wheat genome to improve wheat yield. Among them, 1RS from 'Petkus' rye has been widely used throughout nations as a form of 1BL/1RS translocation. A number of methods to identify rye chromatin in the wheat chromosome such as PAGE, monoclonal antibody, and HPLC have been developed and directly applied in wheat breeding programs. Although disease resistance genes of wheatrye translocation lines are beneficial, some genes residing on 1RS provide deleterious end-use quality in some genetic backgrounds. This problem might be solved using molecular biology. Development of numerous markers closely linked to the genes allows for the introgression of the desirable genes. However, the lack of sequence information owing to the genome structure of rye has limited marker development. With the advent of NGS technology in the 2000s, enormous sequence data are available, especially for 1RS. The combination of NGS and chromosome-based analysis will help positional cloning of useful genes and marker development in 1RS, which results in further employment of rye chromatin in wheat breeding.