Discovering new mechanisms of abiotic stress tolerance in endemic Australian Nicotiana species
thesisposted on 2022-03-28, 16:37 authored by Richard A. O'Brien
Global climate change is predicted to cause more frequent extreme weather events over the next century. These events will exacerbate various abiotic stresses, including drought and high temperatures, each of which can inhibit growth and threaten survival of natural and managed plant systems. This study postulates that wild Australian relatives of Nicotiana from very arid sites might reveal unique characteristics that confer tolerance of hot environments. This may serve high implications in managing agricultural systems and understanding plant species that are sensitive to increased heat. A multi-disciplinary approach investigated heat tolerance at plant, leaf, cell and gene levels. Physiological analysis including growth analysis and gas exchange, suggested that N. megalosiphon and N. tabacum L. tolerated heat stress best among the five species tested. However, solute leakage from leaves of N. megalosiphon did not reveal superior cell membrane integrity under heat stress. A preliminary molecular analysis of a gene known to be vulnerable to heat-stress, Rubisco activase (RCA), revealed some putative amino acid changes between N. tabacum L. and N. benthamiana. This could imply divergent evolution between these two species, particularly in N. tabacum L. which has been highly selected for hot environments under cultivation.