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Delacy, I.H.

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Delacy
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I.H.
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Delacy, I.H.

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  • Using molecular marker order to compare genetic structure in plant populations undergoing selection
    (UCLA Department of Statistics, 2013) Arief, V.N.; Delacy, I.H.; Wenzl, P.; Dreisigacker, S.; Crossa, J.; Dieters, M.; Basford, K.E.
    Many ecological studies compare the genetic structure of populations undergoing natu- ral or artificial selection across different environments. High-throughput molecular markers are now commonly used for these comparisons and provide information on the adapta- tion of the populations to their environments. The genetic structure reflects the history of selection, mutation, migration, and the reproductive breeding system of the populations in their environments. This can be investigated by comparing the ordering of markers obtained from the population with that provided by a recombination or physical map. In populations undergoing selection many genes (markers) have low or zero frequency and commonly used disequilibrium coefficients become unstable under these conditions. A method is presented for ordering bi-allelic markers for populations of self-fertilizing plant species which consist of mixtures of related homozygous genotypes. This provides stable pairwise marker similarity measures even when marker frequencies are low, identification of marker combinations that reflect phenomena that cause differentiation (such as selection and migration), and genetic information on the adaptation of the populations to the environments. The method is illustrated using data from a plant breeding program and inferences are made about accumulation of desirable genes (such as for disease resistance).
    Publication
  • Lines tested in the International Spring Wheat Yield Nurseries (ISWYN) 1964-1994
    (CIMMYT, 1996) Delacy, I.H.; Skovmand, B.; Fox, P.N.; Rajaram, S.; Van Ginkel, M.
    This publication marks the end of an era; after 30 years, the International Spring Wheat Yield Nursery (ISWYN), flagship of the international yield nurseries, has been discontinued. The ISWYN will be replaced by several yield nurseries, each aimed at specific mega-environments. The ISWYN, the first truly international yield nursery, served as a model for similar nurseries in other cereal crops. It was a source of information on adaptation of spring wheat and a means of distributing germplasm to international programs. Thanks to the ISWYNs, where some wheats have appeared under 13 synonyms, we realized the importance of unique identification of germplasm. This principle has become operational through the International Wheat Information System, which encompasses all data manipulation within the Wheat Program. The discontinuation of ISWYN could be temporary; at some future date a global yield nursery may again be needed as a research tool.
    Publication