George Acquaah - Principles of Plant Genetics and Breeding

Gaur, P.M. International Crops Research Institute for the Semi‐Arid Tropics, Patancheru, Hyderabad 502 324, TS, India

Govindaraj, M. International Crops Research Institute for the Semi‐Arid Tropics, Patancheru, Hyderabad 502 324, TS, India

Gramazio, Pietro. Faculty of Life and Environmental Sciences, University of Tsukuba, 1‐1‐1 Tennodai, 305‐8572, Tsukuba, Japan

Grando, S. Independent Consultants, Corso Mazzini 256, 63100, Ascoli Piceno, Italy

Gupta, S.K. International Crops Research Institute for the Semi‐Arid Tropics, Patancheru, Hyderabad 502 324, TS, India

Hammer, K. Institute of Crop Science, Agrobiodiversity Department, University Kassel, Steinstr. 19, D‐37213 Witzenhausen, Germany

Heuser, F. Institute of Crop Science, Agrobiodiversity Department, University Kassel, Steinstr. 19, D‐37213 Witzenhausen, Germany

Hingane, A. International Crops Research Institute for the Semi‐Arid Tropics, Patancheru, Hyderabad 502 324, TS, India

Igwe, David Okeh. Department of Natural Sciences, Bowie State University, Bowie, MD, 20715, USA

Irish, Brian M. USDA‐ARS, TARS Mayaguez, PR, USA

Janila, P. International Crops Research Institute for the Semi‐Arid Tropics, Patancheru, Hyderabad 502 324, TS, India

Jaradat, Abdullah A. ARS‐USDA Research Lab, Morris, MN, 56267, USA

Jeuken, Marieke. Wageningen UR Plant Breeding, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands

Keim, Don L. Delta and Pine Land, MS, USA

Kena, Alexander Wireko. Department of Crop and Soil Sciences, Kwame Nkrumah University of Science and Technology (KNUST), Kumasi, Ghana

Khoshbakht, K. Institute of Crop Science, Agrobiodiversity Department, University Kassel, Steinstr. 19, D‐37213 Witzenhausen, Germany

Kindiger, Bryan. USDA‐ARS, Grazinglands Research Laboratory, 7207 West Cheyenne St., El Reno, Oklahoma, 73036, USA

Myers McClung, Anna. USDA‐ARS, Rice Research Unit, 1509 Aggie Dr., Beaumont, Texas, 77713, USA

Novy, Richard. USDA‐Agricultural Research Service, Aberdeen, ID, USA

Offei, Samuel Kwame. School of Agriculture, University of Ghana, Ghana

Osano, Anne. Natural Sciences Department, Bowie State University, Bowie, MD, 20715, USA

Plazas, Mariola. Instituto de Conservación y Mejora de la Agrodiversidad Valenciana, Universitat Politècnica de València, Camino de Vera 14, 46022 Valencia, Spain

Rooney, William. Texas A & M University, College Station, TX, USA

Sajja, S. International Crops Research Institute for the Semi‐Arid Tropics, Patancheru, Hyderabad 502 324, TS, India

Samineni, S. International Crops Research Institute for the Semi‐Arid Tropics, Patancheru, Hyderabad 502 324, TS, India

Smith, James. USDA‐ARS Crop Genetics and Production Research Unit, Stoneville, MS, USA

Teklu, Y. Institute of Crop Science, Agrobiodiversity Department, University Kassel, Steinstr. 19, D‐37213 Witzenhausen, Germany

Thomas, W.T.B. James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK

Ude, George Nkem. Department of Natural Sciences, Bowie State University, Bowie, MD, 20715, USA

Chapter 1 Introduction

Chapter 2 History of plant breeding

It is informative for students of plant breeding to have a historical perspective of the discipline. Understanding the timeline of advances in one's discipline is instructive in itself. It helps the student to put current advances in plant breeding in the proper perspective, appreciating the challenges and opportunities along the way as professionals contributed to knowledge in the discipline.

Agriculture is the deliberate planting and harvesting of plants and herding animals. This human invention has and continues to impact society and the environment. Plant breeding is a branch of agriculture that focuses on manipulating plant heredity to develop new and improved plant types for use by society. People in society are aware and appreciative of the enormous diversity in plants and plant products. They have preferences for certain varieties of flowers and food crops. They are aware that whereas some of this variation is natural, humans with special expertise (plant breeders) create some of it. Also, there is a general perception that such creations derive from crossing different plants. This introductory chapter is devoted to presenting a brief overview of plant breeding, including its benefits to society and some historical perspectives. After completing this chapter, the student should have a general understanding of:

1 The need and importance of plant breeding to society.

2 The goals of plant breeding.

3 The art and science of plant breeding.

4 Trends in plant breeding as an industry.

5 Selected milestones and accomplishments of plant breeders.

6 The future of plant breeding in society.

Plant breedingis a deliberate effort by humans to nudge nature, with respect to the heredity of plants, to an advantage. The changes made in plants are permanent and heritable. The professionals who conduct this task are called plant breeders. This effort at adjusting the status quo is instigated by a desire of humans to improve certain aspects of plants to perform new roles or enhance existing ones. Consequently, the term “plant breeding” is often used synonymously with “plant improvement” in modern society. It needs to be emphasized that the goals of plant breeding are focused and purposeful. Even though the phrase “to breed plants” often connotes the involvement of the sexual process in effecting a desired change, modern plant breeding also includes the manipulation of asexually reproducing plants (plants that do not reproduce through the sexual process). Breeding is hence about manipulating plant attributes, structure, and composition to make them more useful to humans. It should be mentioned at the onset that it is not every plant character or trait that is readily amenable to manipulation by breeders. However, as technology advances, plant breeders are increasingly able to accomplish astonishing plant manipulations – needless to say not without controversy, as is the case involving the development and application of biotechnologyto plant genetic manipulation. One of the most controversial of these modern technologies is transgenesis, the technology by which gene transfer is made across natural biological barriers.

Plant breeders specialize in breeding different groups of plants. Some focus on field crops (e.g. soybean, cotton), horticultural food crops (e.g. vegetables), ornamentals (e.g. roses, pine trees), fruit trees (e.g. citrus, apple), forage crops (e.g. alfalfa, grasses), or turf species (e.g. Bluegrass, fescue). More importantly, breeders tend to specialize in or focus on specific species in these groups (e.g. corn breeder, potato breeder). This way, they develop the expertise that enables them to be most effective in improving the species of their choice. The principles and concepts discussed in this book are generally applicable to breeding all plant species.

The plant breeder uses various technologies and methodologies to achieve targeted and directional changes in the nature of plants (nudge nature to the advantage of humans). As science and technology advance, new tools are developed while old ones are refined for use by breeders. Before initiating a breeding project, clear breeding objectives are defined based on factors such as producer needs, consumer preferences and needs, and environmental impact. Breeders aim to make the crop producer's job easier and more effective in various ways. They may modify plant structure so it would resist lodging and thereby facilitate mechanical harvesting. They may develop plants that resist pests so the farmer does not have to apply pesticides, or apply smaller amounts of these chemicals. Not applying pesticides in crop production means less environmental pollution from agricultural sources. Breeders may also develop high yielding varieties (or cultivars) so the farmer can produce more for the market to meet consumer demands while improving his or her income. The term cultivar is reserved for variants deliberately created by plant breeders and will be introduced more formally later in the book. It will be the term of choice in this book.