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Title:Genetic dissection of sorghum height and maturity variation using sorghum converted lines and their exotic progenitors
Author(s):Higgins, Race
Advisor(s):Brown, Patrick J.
Department / Program:Crop Sciences
Discipline:Crop Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):sorghum height
sorghum maturity
sorghum conversion lines
Abstract:Sorghum is a photoperiod-sensitive, short-day tropical species that shows long delays in flowering at temperate latitudes. Most temperate-adapted sorghum cultivars are photoperiod-insensitive and dwarfed for grain production. Classical segregation studies predict that temperate adaptedness involves four major loci each for maturity and dwarfing. Two major maturity loci, Ma1 (PRR37) and Ma3 (phytochrome B), and a single major dwarfing locus, Dw3 (PGP1/br2), have been cloned. Sorghum conversion (SC) lines are exotic varieties that have been introgressed with early maturity and dwarfing QTL from a common, temperate-adapted donor using a minimum of four backcrosses. In this study partially-isogenic populations were generated by crossing six diverse SC lines to their corresponding exotic progenitor (EP) lines to assess the phenotypic effects of individual introgressions from the temperate-adapted donor. Initial genotyping results revealed one of the six populations resulted from an outcross. In summer 2012, 192 F3 lines from the five remaining populations were phenotyped for plant height and maturity. Subsets of 109-175 F3 lines were genotyped using Illumina genotyping-by-sequencing (GBS) and used for QTL analysis. QTL models explained 62.31-88.16% of the phenotypic variation for height and maturity in these partially isogenic populations. Nearly all variation was accounted for by the linked Ma1/Dw2 loci on chromosome 6 and the Dw3 and Dw1 loci on chromosomes 7 and 9 respectively. The Dw1 locus fractionated into linked QTL for height and maturity, and a novel height QTL on chromosome 3 was discovered. Evidence is presented for multiple functionally distinct alleles at Ma1, and for large differences in recombination rate among populations on chromosome 6. Candidate genes underlying QTL for Dw2, Dw1, and the new Dw1-linked maturity locus on chromosome 9 are discussed.
Issue Date:2014-01-16
Rights Information:Copyright 2013 Race Higgins
Date Available in IDEALS:2014-01-16
Date Deposited:2013-12

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