Oral Presentation International Plant Molecular Biology Conference 2024

Trait variation and mechanisms of adaptation in Themeda triandra (kangaroo grass) across the Australian continent. (#357)

Vinod Jacob 1 , Jazmine L Humphreys 2 , Ian J Wright 1 , Brian J Atwell 3
  1. Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
  2. School of Natural Sciences, Biological Sciences, University of Tasmania, Hobart, TAS, Australia
  3. School of Natural Sciences, Macquarie University, Sydney, NSW, Australia

More than 1000 species of grasses occur across Australia. Themeda triandra (kangaroo grass) is the most widely distributed of these native grasses, with accessions in our collection originating from every biome in the land. Themeda triandra (a C4 grass) tolerates a broad range of contrasting environmental conditions, presumably due to a combination of phenotypic plasticity and locally adapted genetic variation. Genomic variation in Themeda is likely to be driven by a combination of spatial and climate factors. Given the geographic distance between kangaroo grass populations, we speculate that there is a high degree of local genetic variation across our germplasm, with natural gene flow playing a limited role in adaptation. Survival of populations in future climate regimes will depend upon the degree of phenotypic plasticity. Comparative transcriptomics across distinct Themeda populations grown under contrasting thermal regimes will be reported. Initially, we will align the transcriptome sequences to the reference genome to call genetic variants across genotypes. Annotated variant sequences will be used to identify candidate genes responsible for adaptation in contrasting genotypes. By comparing gene expression profiles between abiotic stress treatments, we can determine whether dynamic gene expression responses to an imposed stress are conserved or unique across populations. Ultimately, combining variant analysis (changes in underlying DNA sequence of a given gene) with dynamic changes in gene expression (changes in how the gene is regulated) should lead to a better understanding of whether phenotypic plasticity, adaptive genetic variation, or both, are the likely cause of climate adaptation in T. triandra.