Preface to the Volume

The Family Cucurbitaceae (cucurbits hereafter) has 118 genera and 825 species distributed primarily in the tropics and subtropics. It contains some of the most nutritious, delicious and versatile food items in the human diet. For example, watermelon contains 40% more lycopene than tomatoes and lycopene is a powerful antioxidant that may lower the risk of certain cancers and heart diseases. Melon is the main source of dietary β-carotene together with carrots and broccoli. But only seven species of four genera are economically important: Citrullus lanatus (watermelon), Cucumis sativus (cucumber), Cucumis melo (melon), Cucurbita pepo (squash, gourd, and pumpkin), Cucurbita maxima (squash), Cucurbita moschata (squash and pumpkin), and Lagenaria vulgaris (L. siceraria, bottle gourd). Less prominent are Luffa (Luffa acutangula and L. cylindrica), bitter melon (Momordica charantia), and waxy gourd (Benincasa hispida).

The last two decades have proved to be the most exciting period in cucurbit research although breeding effort and genetic/genomic studies mostly focused on the economically more important cucurbits, i.e., cucumber, melon and watermelon. Cucumber becomes the fi rst cucurbit to be sequenced, after other fi eld crops such as rice, sorghum, soybean and maize. Its 26,682 predicted genes will facilitate genetic studies and marker development in other closely related cucurbits such as melon and watermelon. High-density genetic maps are now available for cucumber, melon, watermelon and squash. More effi cient and abundant marker systems such as SNP and SSR are being developed. Genomic resources such as sequenced ESTs, large-insert genomic libraries, high-throughput sequencing have been or are being developed for cucurbits. Molecular breeding using markers linked to agronomically important traits has become an effi cient tool in speeding up the new variety release.

This book provides an indepth review of the current state-of-the-art of genetic and genomic research conducted in cucurbits. Each chapter is authored by specialists in their fi eld to report the latest trends and fi ndings. The chapters are well documented and illustrated. The hard work of all contributors is greatly appreciated.

The book begins with an exhaustive description of cucurbits in terms of classifi cation, geographical distribution, production and their importance in our diet (Chapters 1 and 2). These are followed by a discussion on how traditional cucurbit breeding has produced a vast number of new varieties that meet the needs of modern consumers (Chapter 3). Chapter 4 extends the discussion to breeding of novelty cucurbits, i.e., squash for decoration and pumpkins for Halloween, a popular tradition for children in the United States. Chapter 5 describes the applications of genetic markers to diversity analysis in cucurbits. Genetic mapping and map-based cloning of cucurbit genes are described in Chapter 6. This is followed by a discussion in mapping of monogenic traits and molecular breeding in Chapter 7. Chapter 8 expands the discussion to mapping of quantitative traits, which include majority of agronomically important traits in cucurbits. The following three chapters, Chapters 9, 10, and 11, describe the progress in research using -omics in melon, watermelon and cucumber, respectively. Chapter 12 is devoted into an important topic of cucurbits: sex expression as both genetic and environmental factors can change sex expression of cucurbit fl owers. And fi nally, Chapter 13 provides perspectives on cucurbit research areas that may become increasingly important.

This book is a testimony to the substantial progress made in the fi eld of cucurbit genetics, genomics and breeding, and the defi nite value of cucurbits as a model system to study niche area such as sex expression. It is true that the tools and concepts that are presented in the book will continue to evolve rapidly and we hope this volume will provide a solid foundation for further development in cucurbit genetics, genomics and breeding.