Principles of Plant Genetics and Breeding. George Acquaah

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      21 Murphy, D. (2007). Plant Breeding and Biotechnology: Societal Context and the Future of Agriculture, 1e. Cambridge, UK: Cambridge University Press.

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Internet resources

      1 Fernandez‐Cornejo, J. (2004) The Seed Industry in U.S. Agriculture: An Exploration of Data and Information on Crop Seed Markets, Regulation, Industry Structure, and Research and Development. Agriculture Information Bulletin Number 786, Resource Economics Division, Economic Research Service, U.S. Department of Agriculture. http://www.ers.usda.gov/publications/AIB786/

      2 Knight, J. (2003). A dying breed. Nature 421: 568–570. http://www.cambia.org/daisy/cambia/319.

      3 Lindner, R. (2004) “Economic Issues for Plant Breeding ‐‐ Public Funding and Private Ownership.” Australasian Agribusiness Review 12, Paper 6. http://www.agrifood.info/review/2004/Lindner.html

      4 Wehner, T.C. (2005) “History of Plant Breeding.” Plant Breeding Methods, North Carolina State University. http://cuke.hort.ncsu.edu/cucurbit/wehner/741/hs741hist.html

Outcomes assessment

      Part A

      Please answer the following questions true or false:

      1 J.H. Muller is associated with the discovery of the possible effect X‐rays on the genetic material.

      2 The term “heterosis” was coined by G.H. Shull.

      3 Gregor Mendel is the author of the book On the origin of species.

      4 Fred Sanger won the Nobel Peace Prize in 1970 for being the chief architect of the Green Revolution.

      Part B

      Please answer the following questions:

      1 The term “recurrent selection” was coined by ……………………………….

      2 For what contribution to tissue culture are Murashige and Skoog known?

      3 Who was Norman Borlaug?

      Part C

      Please discuss in the following questions in detail:

      1 How is the farmer in a developing country like a plant breeder?

      2 Describe the contribution made by each of the following persons to modern plant breeding: Luther Burbank, Louis de Vilmorin, Joseph Koelreuter.

      3 Briefly discuss the changes in the laws and policies that have impacted plant breeding over the years.

      4 How has the science of plant breeding changed over the years?

      5 Discuss the impact of DNA technologies on plant breeding.

      6 Discuss the role of plant breeding in the Green Revolution.

Section 2 Population and quantitative genetic principles

       Chapter 3 Introduction to concepts of population genetics

       Chapter 4 Introduction to concepts of quantitative genetics

      Plant breeders develop new cultivars by modifying the genetic structure of the base population used to start the breeding program. Students need to have an appreciation for population and quantitative genetics in order to understand the principles and concepts of practical plant breeding. In fact, there is what some call the breeders' equation, a mathematical presentation of a fundamental concept that all breeders must thoroughly understand. This section will help the student understand this and other basic breeding concepts.

3 Introduction to concepts of population genetics

      Purpose and expected outcomes

       Plant breeders manipulate plants based on the modes of their reproduction (i.e. self‐ or cross‐pollinated). Self‐pollinated plants are pollinated predominantly by pollen grains from their own flowers, whereas cross‐pollinated plants are predominantly pollinated by pollen from other plants. These different reproductive behaviors have implications in the genetic structure of plant populations. In addition to understanding Mendelian genetics, plant breeders need to understand changes in gene frequencies in populations. After all, selection alters the gene frequencies of breeding populations. After studying this chapter, the student should be able to:

      1 Define a population.

      2 Discuss the concept of a gene pool.

      3 Discuss the concept of gene frequency.

      4 Discuss the Hardy‐Weinberg law.

      5 Discuss the implications of the population concept in breeding.

      6 Discuss the concept of inbreeding and its implications in breeding.

      7 Discuss the concept of combining ability.

3.1 Concepts of a population and gene pool

      Some breeding methods focus on individual plant improvement, whereas others focus on improving plant populations. Plant populations have certain dynamics, which impact their genetic structure. The genetic structure of a population determines its capacity to be changed by selection (i.e. improved by plant breeding). Understanding population structure is key to deciding the plant breeding options and selection strategies to use in a breeding program.

      3.1.1 Definitions

A population is a group of sexually interbreeding individuals. The capacity to interbreed implies that every gene within the group is accessible to all members through the sexual process. A gene pool is the total number and variety of genes and alleles in a sexually reproducing population that is available for transmission to the next generation. Rather than the inheritance of traits, population genetics is concerned with how the frequencies of alleles in a gene pool change over time. Understanding population structure is important to breeding by either conventional or unconventional methods. It should be pointed out that the use of recombinant DNA technology, as previously indicated, has the potential