Sorghum (Sorghum bicolor, L. Moench) is a staple cereal food crop for millions of people in Sub-Saharan Africa and Asia. However, drought due to low and unpredictable rainfall decreases its productivity in semiarid regions. Understanding the genetic architecture of adaptive traits (drought tolerance, photoperiodic flowering time, and panicle architecture) of sorghum germplasm from breeding programs across West Africa could contribute to efficient molecular breeding. Breeding priorities in West African sorghum improvement programs seek to develop drought-adapted varieties with yield advantages, early and moderate maturity. However, field phenotyping for adaptation in early generations is difficult and there is limited technology to rapidly develop better-adapted varieties. This study aimed to dissect the genetic architecture of adaptive traits to develop high-throughput breeder-friendly markers for rapid introgression of adaptive alleles from donor to elites lines. In chapter 1, I describe the sorghum breeding programs in Senegal, the agronomic importance of sorghum types, and genomic approaches for crop improvement in semiarid regions. In chapter 2, I characterize 213,916 single nucleotide polymorphisms (SNPs) across 421 Senegalese sorghum accessions from the USDA-Germplasm Resources Information Network (GRIN) to identify genomic signatures of local adaptation. This study provided insights into the factors shaping the genetic diversity and the molecular systems underlying local adaptation to water scarcity in sorghum, a staple food security crop in Senegal. In chapter 3, I characterize 159,101 SNPs across 756 accessions of the West African sorghum association panel (WASAP) assembled from breeding programs of Senegal, Niger, Mali, and Togo. The genetic diversity structured by botanical types and subpopulations within botanical types across countries and large-effect quantitative trait loci (QTL) for photoperiodic flowering indicate an oligogenic architecture of flowering time in West African sorghum. In chapter 4, I use genome-wide SNP variation from chapter 3 and phenotypic data from multiple managed water stress environments to identify genomic regions associated with drought response. Significantly positive pleiotropic associations contributed to high phenotypic variance and colocalized with known stay-green (Stg) QTLs, suggesting the existence of Stg alleles in West African sorghum. Finally, in chapter 5, I summarize the expected steps to establish genomics-enabled breeding for sorghum improvement in West Africa. The genomic resources developed in this research have allowed for the dissection of the genetic architecture of adaptive traits. The SNPs associated with large-effect QTLs can be converted into high-throughput breeder-friendly markers for use in marker-assisted selection. These resources combined with discoveries from the global scientific community can be used to accelerate and facilitate the development of locally adapted varieties to meet global food demand in semiarid regions of Sub-Saharan Africa.

The world population is estimated to reach to more than 10 billion by the year 2050. These projections pose a challenging situation for the agricultural scientists to increase crops productivity to meet the growing food demands. The unavailability and/or inaccessibility to appropriate gene pools with desired traits required to carry out genetic improvement of various crop species make this task formidable for the plant breeders. Incidentally, most of the desired genes reside in the wild genetic relatives of the crop species. Therefore, exploration and characterization of wild genetic resources of important crop species is vital for the efficient utilization of these gene pools for sustainable genetic improvements to assure food security. Further, understanding the myriad complexities of genic and genomic interactions among species, more particularly of wild relatives of crop species and/or phylogenetically distant germplasm, can provide the necessary inputs to increase the effectiveness of genetic improvement through traditional and/or genetic engineering methods. This book provides comprehensive and latest insights on the evolutionary genesis of diversity, access and its utilization in the evolution of various crop species. A comprehensive account of various crops, origin, exploitation of the primary, secondary and tertiary gene pools through breeding, biosystematical, cytogenetical and molecular phylogenetical relationships, and genetic enhancement through biotechnological interventions among others have been provided as the necessary underpinnings to consolidate information on the effective and sustainable utilization of the related genetic resources. The book stresses upon the importance of wild germplasm exploration, characterization and exploitation in the assimilation of important crop species. The book is especially intended for students and scientists working on the genetic improvement of crop species. Plant Breeders, Geneticists, Taxonomists, Molecular Biologists and Plant Biotechnologists working on crop species are going to find this book very useful.

It appears that a comprehensive and up-to-date book on the impact of virus diseases on the major crops in developing countries is now much needed, especially as there have been rapid advances in the biological and molecular characterization and detection of the pathogens and possible approaches for their control. On the other hand, the economic losses caused by many of these diseases are tremendous and much of the accumulated knowledge to diminish the crop losses has not filtered through, or cannot be applied. This book is focused on the important crops. Each chapter on a specific crop will include inter alia, geographical distribution, the viruses - symptoms, damage, detection - a brief description of the viruses concerned, and present and future ways for their control. Experts from India, Nigeria, UK, USA, France, Germany, Peru, Japan, Australia, Netherlands, Venezuela, Kazakhstan and Israel (many of them from the International Research Institutions) have contributed chapters to this book.

Increased agricultural productivity is a major stepping stone on the path out of poverty in sub-Saharan Africa and South Asia, but farmers there face tremendous challenges improving production. Poor soil, inefficient water use, and a lack of access to plant breeding resources, nutritious animal feed, high quality seed, and fuel and electricity-combined with some of the most extreme environmental conditions on Earth-have made yields in crop and animal production far lower in these regions than world averages. Emerging Technologies to Benefit Farmers in Sub-Saharan Africa and South Asia identifies sixty emerging technologies with the potential to significantly improve agricultural productivity in sub-Saharan Africa and South Asia. Eighteen technologies are recommended for immediate development or further exploration. Scientists from all backgrounds have an opportunity to become involved in bringing these and other technologies to fruition. The opportunities suggested in this book offer new approaches that can synergize with each other and with many other activities to transform agriculture in sub-Saharan Africa and South Asia.