Genetic Resources, Chromosome Engineering, and Crop Improvement: Grain Legumes, Volume I PDF

Preface

Cereal crops — mainly wheat, rice, maize, pearl millet, and sorghum — constitute the primary food source of the world population. While cereals are an excellent source of energy in the form of carbohydrates, grain legumes (common bean, pea, pigeonpea, cowpea, lentil, chickpea, and others) (family Fabaceae) are the major, if not the only, source of dietary protein for a large proportion of the population in Asia, Africa, and other impoverished regions. Seeds of primary grain legumes are consumed as daal and soup, while flour is used for preparing snacks or mixed with cereal flour for baking wholesome "chapattis." Legumes also play a positive role in crop rotations with cereals and help replenish soil's nitrogen supply. Their characteristic root nodules harbor the rhizobial bacteria that bring about nitrogen fixation in the soil. Cereals and legumes form a unique combination in the diet of the poor, who cannot afford animal protein. Thus, grain legumes are sometimes called the poor man's meat. They are the primary source of protein for people (predominantly in India) who are strictly vegetarian and will not consume any form of animal protein. In addition to their rich protein content, pulses such as chickpea have a unique combination of nutrients, including iron, calcium, and zinc, as well as members of the vitamin B complex, which makes them an ideal component of the human diet. According to Nancy Longnecker at the Centre for Legumes in Mediterranean Agriculture at The University of Western Australia (www.research.deakin.edu.au), "Eating more legumes lowers the risk of heart disease, type-II diabetes, and obesity." She further stated that a U.S. study lasting 19 years involving 9600 men and women showed that those who "ate four or more servings of legumes (including chickpea) per week were 22% less likely to suffer from coronary heat disease than those who ate less than one serving per week." Therefore, researchers around the globe are constantly in search of legumes as a supplement in improving modern human diets. Despite their nutritional superiority and great importance to human health, grain legumes have not received the attention they deserve – in fact, not even half the attention cereals have claimed. It is ironic that although pea ( Pisum sativum L.) formed the experimental material in the seminal hybridization work of the founder of genetics, Johann Gregor Mendel, in the 1860s, genetic improvement of this important legume has lagged far behind that of other crops. The importance of bringing about genetic improvement of leguminous crops cannot be overemphasized.

Improving yields of the grain legumes remains a primary breeding goal of various national and international programs. Many of these centers maintain germplasm resources as potential donors of genes for resistance to various biotic and abiotic stresses. Because there is no consolidated account of germplasm resources and cytogenetic manipulation and breeding of grain legumes, we planned to bring out such a book that constitutes volume I in a series on "germplasm resources, chromosome engineering, and crop improvement." The idea of bringing out this series of five volumes, each dealing with grain legumes, cereals, oilseed crops, vegetable crops, and forage crops, was first conceived by one of us (Singh), and world-renowned scientists were invited to contribute chapters on various crops. This volume consists of 11 chapters dealing with major grain legumes of great economic importance to developing countries and to the developed world. These chapters give comprehensive and authoritative accounts of genetic resources and their utilization for improving yields, disease, and pest resistance — and other agronomic traits of the most widely grown and consumed legumes.

The introductory chapter summarizes the landmark research done in ten leguminous crops, giving, in tabulated form, information on germplasm availability for breeding for high yields and improved protein content. Appropriate germplasm collections can be a good source for genetic enhancement of various traits in grain legumes and for broadening their genetic base. Each of the subsequent chapters, 2–11, deal, respectively, with one of the 10 crops: common bean ( Phaseolus vulgaris L.), pea ( Pisum sativum L.), pigeonpea [ Cajanus cajan (L.) Millsp.], cowpea [ Vigna unguiculata (L.) Walp.], faba bean ( Vicia faba L.), chickpea ( Cicer arietinum L.), lentil ( Lens culinaris Medik.), lupin ( Lupinus L.), mungbean [ Vigna radiata (L.) Wilczek], and azuki bean [ Vigna angularis (L.) Ohwi & Ohashi]. Each chapter provides comprehensive information on the origin of the crop, its genetic resources in various gene pools, basic cytogenetics, conventional breeding, and the modern tools of molecular genetics and biotechnology. The primary (GP-1), secondary (GP-2), and tertiary (GP-3) gene pools of each crop are identified. Utilization of these resources in producing high-yielding cultivars with resistance to biotic and abiotic stresses is also described. In view of the narrow genetic base of various legumes, several authors have recommended the use of GP-2 and GP-3 resources in producing widely adapted varieties by wide hybridization. In addition to superior nutritional components stated above, some grain legumes contain antinutritional elements, and the authors have recognized such undesirable traits in the crops they have dealt with. There is ongoing research to produce varieties without — or with only low amounts of — antinutritional elements by conventional breeding and transgenic technology.

Each chapter has been written by one or more experts in the field. We are extremely grateful to all the authors for their invaluable contributions. We have been fortunate to know them both professionally and personally. We are also very grateful to scientists who reviewed various chapters. Our communications were always cordial and friendly. We are particularly indebted to Daniel Debouck, Ian Dundas, James Kelly, Tanveer Khan, Phil Miklas, Srinivas Rao, Bob Redden, Fred Muehlbauer, José Cubero, Kadambot Siddique, Govindjee, and Deoki Tripathy for their comments and suggestions on some of the chapters. Although every chapter has been appropriately reviewed by experts in the field, the authors are ultimately responsible for the accuracy and completeness of their respective chapters. One of us (Singh) would like to thank Dr. Steven G. Pueppke, Associate Dean and Research Director at the University of Illinois, Urbana, for all his support and encouragement.

This book is intended for professionals and graduate students whose interests center upon genetic improvement of crops in general, and grain legumes in particular. The book will benefit plant breeders, agronomists, cytogeneticists, taxonomists, molecular biologists, and biotechnologists. Graduate-level students in these disciplines with adequate background in genetics and a spectrum of other researchers interested in biology and agriculture will also find this volume a worthwhile reference. We sincerely hope that the information in this book will help in the muchneeded genetic amelioration of grain legumes.