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Genomics underlying Chilling and Freezing Stress Responses and Adaptation in Sorghum (Sorghum bicolor (L) Moench)

Niegel Desmond La Borde, University of Nebraska - Lincoln


Sorghum (Sorghum bicolor L.) is a tropical C4 grass with enormous potential for biofuel production in the Great Plains. Cold stress is a major abiotic stress limiting sorghum (Sorghum bicolor L.) growth and productivity in the Great plains. The development of chilling tolerant sorghum cultivars may allow for expansion of the growing regions and may confer many of the benefits of early season planting. This dissertation focuses on the complex genetics underlying both chilling and freeze tolerance in sorghum. To identify these areas, we will employ two strategies. First, using two population of RIL lines, developed from a cross between chilling-sensitive (Tx430; M81E) and chilling-tolerant cultivars (CT19; ISCV700), Linkage maps for each population, spanning 2080.1 cM and 1515.2 cM respectively were created from single nucleotide polymorphisms (SNPs) derived from genotype-by-sequencing (GBS). To evaluate early season chilling tolerance the two populations were evaluated for germination, emergence, chlorophyll content, root and shoot development in two field locations over three years and in controlled environments under optimal and suboptimal conditions. QTLs associated with early-season performance were identified by composite interval mapping (CIM). The physiology of freezing tolerance were evaluated, on the two populations, through a indoor protocol on coldacclimated and nonacclimated sorghum. A QTL approach was used to identify areas in the genome associated with freezing tolerance. QTLs for both chilling and freezing stress were detected for both sorghum populations. QTLs were found to colocalize for several physiological traits indicating the omplex genetic machinery underlying sorghums response to chilling and freezing temperatures. genes identified in major QTL regions are promising steps in the development of sorghum cultivars for the temperate Great Plains.

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Recommended Citation

La Borde, Niegel Desmond, "Genomics underlying Chilling and Freezing Stress Responses and Adaptation in Sorghum (Sorghum bicolor (L) Moench)" (2017). ETD collection for University of Nebraska-Lincoln. AAI10616545.