Utilization of Wild Species for Wheat Improvement Using Genomic Approaches

Abstract

Wheat is one of the most important food crops in the world in terms of the area, production, and nutrition. It can grow in varied tropical and temperate climates ranging from a few meters to more than 3800 m above sea level. In spite of a wide range of climatic adaptability, a number of biotic and abiotic stresses limit its yield stability. Wild wheat relatively belonging to primary, secondary, and tertiary gene pool contains untapped variation for wheat improvement, both for biotic and abiotic stresses that could be incorporated in cultivated wheat. Diversity of primary gene pool can be incorporated by simple hybridization methods, while diversity of secondary gene pool of Triticum and Aegilops species, sharing one genome common with wheat, can be transferred with slight manipulations in hybridization. Species belonging to the tertiary gene pool are more distantly related to wheat. To transfer variation from these species to common wheat, special cytogenetic manipulations are required. Availability of various genomic resources of wild species of wheat is making an easy way to reach the genes which become possible because of recent developments in sequencing technologies. These platforms enabled the sequencing of progenitor species of wheat like T. urartu, Aegilops tauschii, wild emmer wheat, and Triticum monococcum as well as transcriptome sequencing of non-progenitor species like Aegilops sharonensis and Agropyron cristatum. Sequence data thus obtained from wild species of wheat hold the potential for the improvement of wheat crop. The genic sequences or expressed sequence tags (ESTs) obtained from the wild species are used to design SNP chips of data capacity 35 K and 820 K which are being used to map and fine map agronomically important genes. Also the technique of flow cytometry enabled the flow sorting of larger genomes which allows the focus only on specific chromosomes containing genes of interest. Besides latest innovation in RenSeq and MutRenSeq allowed the mapping and cloning of disease resistance genes more fast and reliable.