CondensDrought · Can chromosome reorganisation aid adaptation to drought?

The structure and function of plant genomes have been marked by a history of repeated cycles of whole genome duplications followed by diploidization. Despite the number of duplications in their ancestry, most extant plants, particularly herbaceous groups, exhibit low chromosome numbers (e.g. five pairs in Arabidopsis), but the drivers of this descending dysploidy remain little understood. The project will test a classical hypothesis from early in the last century that chromosomal reorganization is driven by selection to create linkage groups favourable for a particular habitat. To address this, I will focus on Nicotiana sect. Suaveolentes, a group with variable ecologies, including adaptation to deserts, and series of chromosome reductions. I will focus of species pairs including a species with higher chromosome number that prefers mesic habitats, and a related species with lower chromosome number that is adapted to extreme arid conditions. I plan to investigate if genes responsible for adaptation to extreme habitats are associated with genomic rearrangements, and in particular test if these genes tend to cluster within fewer linkage blocks than expected by chance. This action will obtain a comprehensive understanding about the contributions of post-WGD processes to evolutionary success and phenotypic novelty, providing new information on how genomic reorganization contributes to adaptation, speciation and adaptive radiation. It will also provide details on genes associated with adaptation to hot, dry habitats, important for understanding plant responses to climate change.