Comparative Genomics of Cereal Crops: Status and Future Prospects

Abstract

Cereals are members of grass family and play an important role in providing food security to billions of people across the globe since the beginning of agriculture. Cereal crops differ considerably from each other in terms of morphology, adaptation and genetic architecture. This has motivated researchers across the world to study their evolution, genetics and development. During the last few decades, phenomenal progress in genomics research has paved the way for comparative genomic studies across crop species, especially the cereals due to their economic importance. These studies together have revealed a good level of conservation across cereals both at macro and micro level. However, most of the comparative studies in cereals prior to genome sequencing projects have been performed at genetic map level. Large-scale genome sequencing projects during the beginning of the twenty-first century, especially in rice, sorghum, maize, barley, wheat and foxtail millet, led to better understanding of the conservations of genes/genomic regions at sequence level. This chapter reviews the status of cereal comparative genomics prior to genome sequencing and progress post-genome sequencing of major cereals. The genomic organization of major cereals has been discussed in detail. The chapter also describes the distinguishing features and the mechanism of evolution of cereal genomes. The advancement in genome sequencing technologies, especially the next-generation sequencing technologies and its effectiveness in performing genomic studies across crops, is also discussed. The various genomic tools, databases and resources for performing comparative genomic studies are reviewed here. The chapter presents the opportunities on how the knowledge gained from comparative genomics of cereals can be used for gene discovery programmes, functional genomics and subsequently genetic improvement of cereal crops.