Massey Documents by Type

Now showing 1 - 3 of 3

Comparative analysis of plastid genomes from allopolyploid Tragopogon miscellus and its diploid parents
(John Wiley and Sons Ltd on behalf of German Society for Plant Sciences, Royal Botanical Society of the Netherlands, 2025-09-15) Mukhtar U; Newmarch SC; Winkworth RC; Soltis PS; Soltis DE; Tate JA; Wang X-Q
Tragopogon is a model system for the study of recent, recurrent, and reciprocal allopolyploid formation. Recent research has focused on the fates of nuclear genes duplicated in the allopolyploid T. miscellus relative to the parental diploids, T. dubius and T. pratensis. In contrast, little attention has been given to organellar genomes, which interact with the duplicated nuclear genomes via their gene products. Here we reconstructed plastid genomes (plastomes) for representatives of these three species to investigate their structure and variability among natural and synthetic allopolyploids. Genomic libraries were Illumina-sequenced for several individuals of the allopolyploid T. miscellus and its diploid parents. Whole plastomes were assembled from skimmed data with comparative analyses used to quantify structural and nucleotide variation. Tragopogon plastomes have a typical quadripartite structure and are similar in size to those of other Asteraceae. The 12 plastomes were highly similar, sharing ~99.5%–100% identity. In all but one case, the plastome sequence for each of the polyploids was most similar to that of its expected maternal parent. The exception involved a polyploid that unexpectedly had a T. dubius plastome type, likely as the result of backcrossing with its presumed paternal parent. Such backcrossing events may have contributed to the demise of this polyploid population. Plastome sequences can be used to infer the maternal origins of polyploids as well as investigate ongoing population-level dynamics. More fully assessing plastome variation across the geographic distribution of polyploids and their diploid progenitors may provide additional insights into polyploid formation, population dynamics, and subsequent evolution.
Reciprocally formed Tragopogon allopolyploids and their diploid parents : a comparative study : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Biology, School of Natural Sciences, Massey University, Palmerston North. EMBARGOED to 14 March 2027.
(Massey University , 2025-02-28) Mukhtar, Usama
Allopolyploidy has been a significant evolutionary force across the eukaryotic tree of life, particularly in plants. Newly formed polyploids inherit traits from their progenitors but may also show transgressive characters that allow them to inhabit different areas and/or outcompete their parents in similar habitats. In this thesis, multiple approaches were used to study differences between reciprocally formed allopolyploids (Tragopogon miscellus) and their diploid parents (T. dubius and T. pratensis) in the genus Tragopogon. This system was chosen because the parentage of the allopolyploids is known and the polyploids were recently (within the last 100 years) formed. These four species were analysed for: growth parameters under variable temperature and water conditions; physiology and cellular characteristics; and variations in plastid genomes. Both reciprocally formed polyploids were found to have different growth profiles from each other, with short-liguled Tragopogon miscellus being potentially more robust. Leaf physiology revealed T. dubius had low water use efficiency, but a higher transpiration capacity than the other diploid T. pratensis and the polyploids. Comparison of whole plastid genomes revealed variations in both DNA sequence and base modifications, including methylation patterns, among the four species. Collectively, these results help further our understanding of phenotypic and genotypic evolution in young allopolyploids.
Evolution of cytonuclear coordination in Tragopogon (Asteraceae) allopolyploids : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Biology at Massey University, Manawatu, New Zealand
(Massey University, 2023) Hussain, Sidra
Cytonuclear coordination is an important aspect in plant evolution which involves the synchronized interactions between nuclear and organellar genomes. Allopolyploidy, resulting from interspecific hybridization and genome duplication, could result in cytonuclear incompatibilities. Therefore, to coordinate cytonuclear interactions, allopolyploids may undergo alterations in duplicated nuclear gene expression via incorporating maternally biased expression patterns. To investigate cytonuclear responses to allopolyploidy, in this study, expression patterns of duplicated nuclear genes and their organelle counterparts, implicated in cytonuclear enzyme complexes, as well as dual-targeted genes were investigated in the reciprocally formed young T. miscellus allopolyploids (90-100 years) and diploid parent species; T. dubius and T. pratensis. In addition, the effect of polyploidy on morphological traits of T. miscellus allopolyploids were examined and assessed relative to parent species. The expression data showed that T. miscellus allopolyploids are regulating expression at the homeolog level, primarily through T. pratensis bias, while maintaining the total gene expression levels as to parental levels. The morphological evaluation of allopolyploids and diploids demonstrated that both reciprocal forms of T. miscellus have significantly longer, but fewer leaves compared to the diploid parent species. These findings reflect that young T. miscellus allopolyploids are certainly undergoing homeolog expression regulation to accommodate cytonuclear interactions as well as displaying morphological responses to allopolyploidy. This study provides insights into polyploid genome evolution and contributes to further understanding of the cytonuclear coordination in allopolyploids.

Massey Documents by Type

Browse

Filters

Settings

Sort By

Results per page

Search Results