Browsing by Author "Paterson, Andrew H."

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    Comparative evolution of vegetative branching in sorghum
    (Plos one, 2021) Kong, WenQian; Nabukalu, Pheonah; Cox, T. Stan; Goff, Valorie; Robertson, Jon S.; Pierce, Gary; Lemke, Cornelia; Compton, Rosana; Reeves, Jaxk; Paterson, Andrew H.
    Tillering and secondary branching are two plastic traits with high agronomic importance, especially in terms of the ability of plants to adapt to changing environments. We describe a quantitative trait analysis of tillering and secondary branching in two novel BC1F2 populations totaling 246 genotypes derived from backcrossing two Sorghum bicolor x S. halepense F1 plants to a tetraploidized S. bicolor. A two-year, two-environment phenotypic evaluation in Bogart, GA and Salina, KS permitted us to identify major effect and environment specific QTLs. Significant correlation between tillering and secondary branching followed by discovery of overlapping sets of QTLs continue to support the developmental relationship between these two organs and suggest the possibility of pleiotropy. Comparisons with two other populations sharing S. bicolor BTx623 as a common parent but sampling the breadth of the Sorghum genus, increase confidence in QTL detected for these two plastic traits and provide insight into the evolution of morphological diversity in the Eusorghum clade. Correspondence between flowering time and vegetative branching supports other evidence in suggesting a pleiotropic effect of flowering genes. We propose a model to predict biomass weight from plant architecture related traits, quantifying contribution of each trait to biomass and providing guidance for future breeding experiments.
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    Detection of quantitative trait loci regulating seed yield potential in two interspecific S. bicolor2 3 S. halepense subpopulations
    (Euphytica, 2021) Nabukalu, Pheonah; Kong, Wenqian; Cox, Thomas S.; Paterson, Andrew H.
    Perennial sorghum cropping offers substantial economic and ecological benefits, conserving fuel, water, and soil. To be perennial in temperate climates, a sorghum plant must over-winter and produce new growth the following spring—a trait derived from the weedy species Sorghum halepense. We have introduced perenniality from S. halepense into a S. bicolor background and identified QTL affecting eight seed yield-related traits and their linkage relationships. Interval mapping in this BC1F2 population derived from S. bicolor × S. halepense revealed a total of 80 QTL with LOD scores greater than 2.5 for the eight traits, with a range of 1 to 13 QTL per trait. Additional QTL were detected in multiple-QTL analyses. The traits mapped in this study showed diverse genetic complexity; the pattern of one major plus several minor QTL was observed for most traits, and traits varied in the number of QTL and direction of allelic effects. For four traits evaluated across locations, some QTL detected in one of the two locations had virtually no effect in the other, suggesting an environmental influence on QTL expression. The results contribute to fundamental knowledge of the genetic architecture underlying seed yield and may support development of high yielding perennial grain sorghum varieties.
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    Development of Perennial Grain Sorghum
    (Sustainability, 2018) Cox, Stan; Nabukalu, Pheonah; Paterson, Andrew H.; Kong, Wenqian; Nakasagga, Shakirah
    Perennial germplasm derived from crosses between Sorghum bicolor and either S. halepense or S. propinquum is being developed with the goal of preventing and reversing soil degradation in the world’s grain sorghum-growing regions. Perennial grain sorghum plants produce subterranean stems known as rhizomes that sprout to form the next season’s crop. In Kansas, breeding perennial sorghum involves crossing S. bicolor cultivars or breeding lines to S. halepense or perennial S. bicolorn × S. halepense breeding lines, selecting perennial plants from F2 or subsequent populations, crossing those plants with S. bicolor, and repeating the cycle. A retrospective field trial in Kansas showed that selection and backcrossing during 2002–2009 had improved grain yields and seed weights of breeding lines. Second-season grain yields of sorghum lines regrowing from rhizomes were similar to yields in the first season. Further selection cycles have been completed since 2009. Many rhizomatous lines that cannot survive winters in Kansas are perennial at subtropical or tropical locations in North America and Africa. Grain yield in Kansas was not correlated with rhizomatousness in either Kansas or Uganda. Genomic regions affecting rhizome growth and development have been mapped, providing new breeding tools. The S. halepense gene pool may harbor many alleles useful for improving sorghum for a broad range of traits in addition to perenniality.
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    High proportion of diploid hybrids produced by interspecific diploid 3 tetraploid Sorghum hybridization
    (Genetic Resources and Crop Evolution, 2018) Cox, Stan; Nabukalu, Pheonah; Paterson, Andrew H.; Kong, Wenqian; Auckland, Susan; Rainville, Lisa; Cox, Sheila; Wang, Shuwen
    A perennial version of grain sorghum [S. bicolor (L.) Moench] would create opportunities for greatly reducing tillage and preventing soil degradation. Efforts to select for perenniality and grain production among progeny of hybrids between S. bicolor (2n = 20) and the weedy tetraploid perennial S. halepense (L.) Pers. (2n = 40) are complicated in that F1 hybrids produced by diploid × tetraploid sorghum crosses are usually tetraploid. In 2013, a set of random pollinations between 19 diploid cytoplasmic male-sterile inbred lines and 43 tetraploid perennial plants produced 165 F1 hybrid plants, more than 75% of which had highly atypical plant, panicle, and seed phenotypes. Phenotypic segregation in F2 populations derived from atypical hybrids was also anomalous. Examination of mitotic metaphase cells in F1 or F2 root tips revealed that 129 of the 165 hybrids were diploid. Parentage of the diploid progenies was confirmed using simple-sequence repeat analysis. The mechanism by which diploid hybrids arise from diploid × tetraploid crosses is unknown, but it may involve either production of monohaploid (n = 10) pollen by the tetraploid parent or chromosome elimination during early cell divisions following formation of the triploid zygote. The ability to produce diploid germplasm segregating for S. bicolor and S. halepense alleles could have great utility, both for the development of perennial sorghum and for the improvement of conventional grain sorghum.
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    Quantitative trait mapping of plant architecture in two BC1F2 populations of Sorghum Bicolor × S. halepense and comparisons to two other sorghum populations
    (Theoretical and Applied Genetics, 2021) Kong, WenQian; Nabukalu, Pheonah; Cox, T. S.; Goff, Valorie H.; Robertson, Jon S.; Pierce, Gary J.; Lemke, Cornelia; Compton, Rosana; Paterson, Andrew H.
    Comparing populations derived, respectively, from polyploid Sorghum halepense and its progenitors improved knowledge of plant architecture and showed that S. halepense harbors genetic novelty of potential value for sorghum improvement Vegetative growth and the timing of the vegetative-to-reproductive transition are critical to a plant’s fitness, directly and indirectly determining when and how a plant lives, grows and reproduces. We describe quantitative trait analysis of plant height and flowering time in the naturally occurring tetraploid Sorghum halepense, using two novel BC1F2 populations totaling 246 genotypes derived from backcrossing two tetraploid Sorghum bicolor x S. halepense F1 plants to a tetraploidized S. bicolor. Phenotyping for two years each in Bogart, GA and Salina, KS allowed us to dissect variance into narrow-sense genetic (QTLs) and environmental components. In crosses with a common S. bicolor BTx623 parent, comparison of QTLs in S. halepense, its rhizomatous progenitor S. propinquum and S. bicolor race guinea which is highly divergent from BTx623 permit inferences of loci at which new alleles have been associated with improvement of elite sorghums. The relative abundance of QTLs unique to the S. halepense populations may reflect its polyploidy and subsequent ‘diploidization’ processes often associated with the formation of genetic novelty, a possibility further supported by a high level of QTL polymorphism within sibling lines derived from a common S. halepense parent. An intriguing hypothesis for further investigation is that polyploidy of S. halepense following 96 million years of abstinence, coupled with natural selection during its spread to diverse environments across six continents, may provide a rich collection of novel alleles that offer potential opportunities for sorghum improvement.