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This article in CS

  1. Vol. 40 No. 3, p. 619-625
    Received: Jan 22, 1999

    * Corresponding author(s): jpopi@dekalb.com
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Random Amplified Polymorphic DNA–Based Evaluation of Diversity in the Hierarchical, Open-Ended Population Enrichment Maize Breeding System

  1. J. Popi *a,
  2. J. Rajnprehtb,
  3. L.W. Kannenbergb and
  4. K.P. Paulsb
  1. a Monsanto Canada Inc., 1288 Glanworth Drive, London, ON, N6N 1H1, Canada
    b Dep. of Plant Agriculture, Univ. of Guelph, ON, N1G 2W1, Canada. Contribution of the Dep. of Plant Agriculture, Univ. of Guelph, Guelph, ON, N1G 2W1, Canada


Commercial maize germplasm has a narrow genetic base. The hierarchical, open-ended population enrichment (HOPE) maize (Zea mays L.) breeding system was created with the dual purpose of developing useful inbred lines and of diversifying the maize breeding germplasm. The objective of this study was to estimate the genetic diversity in the HOPE populations at initiation and after 15 yr of operation. The HOPE system has two heterotic population sets (A and B). Each set has a hierarchical structure and consists of four open-ended populations: elite (E), high (H), intermediate (I), and low (L). New germplasm is added to the system, and high-performing entries from a lower level can be advanced to the next higher level. Increasingly stringent recurrent selection procedures are employed at each higher level of the hierarchy. Twelve random amplified polymorphic DNA (RAPD) primers were used to analyze 19 plants from the initial and last cycle of selection for each of the four levels of the two population sets. The greatest polymorphism (65.9%) was observed for the last selection cycle of the L level of the B set, while the last selection cycle of the E level of the A set was the least polymorphic (39.2%). Intrapopulation diversity was the greatest for the L level, and the smallest for the E level. Diversity appeared to be enhanced due to introgressions and advancements of material in the hierarchy. Principal component (PC) analysis indicated that the populations of the lower levels were more similar to one another than were the two E populations. All polymorphisms present in commercial check hybrids were also observed in the HOPE populations, while 32 of the observed 91 bands were polymorphic in the HOPE system and monomorphic in the hybrids. This study indicates that HOPE populations offer variability not present in commercial material and supports the HOPE system as a source of nontraditional germplasm for maize breeding programs.

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