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Title:Sweet sorghum diversity, genetics, and breeding
Author(s):Burks, Payne S
Director of Research:Brown, Patrick
Doctoral Committee Chair(s):Brown, Patrick
Doctoral Committee Member(s):Kolb, Frederic L.; Lee, D.K.; Moose, Steve
Department / Program:Crop Sciences
Discipline:Crop Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Sweet Sorghum
Genotyping-by-sequencing (GBS)
Quantitative Trait Locus (QTL)
Association Mapping
D Locus
Abstract:Sweet sorghum is characterized by high sugar content and high biomass and is of growing interest to the biofuel industry. For sweet sorghum to be successfully used for bioenergy production, genetic relationships and diversity within sweet sorghums should be better understood, genetic and physiological mechanisms that distinguish sweet from non-sweet sorghums need to be characterized, and higher-yielding sweet sorghum female lines are needed to create sweet hybrids with higher sugar yields. Each of these needs is addressed in a separate chapter of this thesis. The first chapter describes the characterization of genetic differences among sweet sorghum cultivars and diverse landraces of sorghum. Genotyping-by-sequencing (GBS) was conducted on more than 700 sorghum lines to generate genome-wide single nucleotide polymorphism (SNP) data and assess population genetic differences between groups. The genomic region of highest genetic differentiation (FST) between sweet and landrace sorghums contains a sucrose phosphate synthase and invertase candidate gene. The second chapter describes the characterization of phenotypic variation in sugar yield components in sweet and non-sweet sorghum varieties, and the identification of QTL for sugar yield. Phenotyping was performed in three environments on 241 diverse genotypes, and a genome-wide association study was performed using ~50,000 SNPs. The Dry midrib (D) locus was identified as a large-effect QTL for sugar yield. The third chapter describes the development of improved sweet sorghum female lines using phenotypic selection for plant height, flowering time, and sugar yield and marker- assisted selection for the rf1 locus, which controls pollen sterility in A1 cytoplasm. Selection was performed in the F2, F3, and F4 generations of six biparental families derived from crosses between a common female (Tx623) and six different sweet cultivars. Sweet female lines with a range of maturities were developed; these lines have higher sugar yields than Tx623, the female they replace, and are much shorter than the sweet cultivars used as male parents. Overall, these advances in sweet sorghum breeding and genetics will help secure a role for sweet sorghum in the emerging bioenergy economy.
Issue Date:2015-04-20
Rights Information:Copyright 2015 Payne Burks
Date Available in IDEALS:2015-07-22
Date Deposited:May 2015

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