Molecular Breeding for Sustainable Crop Improvement

Wheat production and productivity at the global level has witnessed a remarkable improvement during the last five decades, thus helping in providing food security. However, the annual growth rate in wheat production has declined from *3 % in earlier decades to 0.5–0.7 % in recent years causing concern. Therefore, major worldwide efforts are being made to improve the yield potential of bread wheat. In this connection, alien genetic variation has been found to be an important source of genetic variation both for qualitative and quantitative traits of agronomic importance. A number of alien species belonging to the tribe Triticeae of the family Poaceae have been utilized for this purpose. These alien species have been utilized through the production of amphiploids, whole chromosome alien addition and substitution lines, whole-arm Robertsonian translocations, and the translocations involving small segments of alien chromosomes. The transfer of small segments carrying desirable alien genes was achieved through several approaches including irradiation, use of mutants, and suppression of diploidizing gene (Ph1). These alien resources along with the details of their successful utilization for wheat improvement have been described in this chapter.