Improving Lives: 50 Years of Crop Breeding, Genetics, and Cytology (C-1)

During the past 50 yr, we have witnessed a revolution in the science of plant breeding, genetics, and cytology, and its impact on human lives (e.g., theGreenRevolution). Because of increased productivity, breeding objectives evolved from predominantly improving yield to include greater quality and value-added traits. The discovery of the chemical nature of deoxyribonucleic acid (DNA), coupled with Mendelian genetics led to the refinement of quantitative genetics, the robust use of molecular markers, and transgenic crop plants. Cytogenetics elucidated the physical structure of chromosomes, aided trait and molecular mapping, and greatly enhanced the exploitation of genetic variation from wild relatives, as have transgenes andmutations. The fundamental process of selection has been improved by a better understanding of gene action, when to select, and better methods to select plants and analyze their relationship to the environments in which they grow. Single-seed descent plant breeding methods were popularized and evolved to doubled haploid breeding. Plant breeding, genetics, and cytology remain impact sciences that will continue to improve lives as part of the Evergreen Revolution. “IF I HAVE SEEN FURTHER, it is by standing on the shoulders of giants.”—Isaac Newton SETTING THE STAGE: WHERE WE WERE IN 1955 In understanding the last 50 yr of Crop Breeding, Genetics, and Cytology (Division C-1), it is best to begin by understanding where we were in 1955. The world’s population in 1955 was 2 781 183 648, with an estimated annual growth rate of 1.89% (U.S. Census Bureau, 2005). The population of the USA was 165 931 202, with an annual growth rate of 1.77% (U.S. Census Bureau, 2000). Fifty years later the estimatedworld population is 6 451 058 790 (232% more than in 1955), with an estimated annual growth rate of 1.15% and the population of the USA is 297 585 415 (179%more than in1955;U.S.CensusBureau, 2005) with an annual growth rate of 0.92% (U.S. Central Intelligence Agency, 2005). In 1955, plant breeders, geneticists, and cytologists were within 10 yr of the World War II andmany had served in it and all had lived through it. The population projections were clear and most people understood famine, deprivation, and poverty and remembered theGreatDepression. Theywere also committed to change and to creating a new future. The state of our science was that the structure of DNA waselucidated in 1953 (WatsonandCrick, 1953). Similarly rapid advancements were being made in cytogenetics and the genetic understanding or transfer of traits (Sears, 1953). Plant breeding had a long and successful history (Fehr, 1991; Stoskopf et al., 1993), but that is not to say that no new breeding methods were developed in the past 50 yr. The early work of Jones and Singleton (1934) and Goulden (1941) that led to single-seed descent breeding methodology was largely overlooked until it was redefined by Brim (1966). Similarly, the tools for the related doubled haploid breeding, which began in the late 1940s, were an omen of the robust methodologies that were created thereafter (Guha and Maheshwari, 1964; Chase, 1951; Kasha and Kao, 1970; Maluszynski et al., 2003). BREEDING AND GENETICS: THEIR INTERRELATED ROLE IN AGRICULTURE AND 50 YEARS OF CHANGING ROLES In the past 50 yr, agriculture has seen spectacular successes that include the Green Revolution (Everson and Gollin, 2003) in wheat (Triticum aestivum L.) and rice (Oryza sativa L.) and the broad acceptance of singlecross hybrids in maize (Zea mays L.). While all of these advances include a significant genetic and breeding component, they also include significant improvements from other fields. For example, the high productivity of semidwarf wheat and rice cultivars was due to their having a greater harvest index and greater straw strength so that they could be grown with irrigation and much higher levels of fertilizer. Single-cross hybrid maize coincided with advances in herbicide technology and in the widening Corn Belt with conservation tillage systems and improved irrigation technology. To protect these higher yields, plant pathologists and entomologists helped plant breeders add disease and insect resistance to their cultivars. For those crops where end-use quality is important, cereal chemists and biochemists developed new methods and often changed technology to more effectively use new cultivars. Quality needs also required that breeding objectives change. Because plant breeders and applied geneticists obtain information from so many sources, almost all plant breeders and geneticists have worked in teams. While many early concepts of the breeding team had the breeder in the center of this cooperative crop improvement effort (e.g., Fig. 1.4 in Poehlman, 1979), many modern teams are more ecosystem based and have the cropping system specialist at the center of the hub and the plant breeder as one of the key scientists providing input. The focus has evolved from crop improvement to managed ecosystem improvement P.S. Baenziger, W.K. Russell, and G.L. Graef, Dep. of Agronomy and Horticulture,Univ.ofNebraska,Lincoln,NE68583-0915;B.T.Campbell, USDA-ARS, Coastal Plains Soil, Water, and Plant Research Center, Florence, SC29501.Acontributionof theUniv. ofNebraskaAgricultural Research Division, Lincoln, Nebraska 68583 and the USDA-ARS. Contribution no. 15070 from the Nebraska Agric. Res. Div. Received 8 Nov. 2005. *Corresponding author ([email protected]). Published in Crop Sci. 46:2230–2244 (2006). CSSA Golden Anniversary Symposium doi:10.2135/cropsci2005.11.0404gas a Crop Science Society of America 677 S. Segoe Rd., Madison, WI 53711 USA Abbreviations: DNA, deoxyribonucleic acid; MAS, marker-assisted selection; NIR, near infrared reflectance; NIT, near infrared transmission; PCR, polymerase chain reaction; QTL, quantitative trait loci. R e p ro d u c e d fr o m C ro p S c ie n c e . P u b lis h e d b y C ro p S c ie n c e S o c ie ty o f A m e ri c a . A ll c o p y ri g h ts re s e rv e d . 2230 Published online September 8, 2006