CondensDrought · Can chromosome reorganisation aid adaptation to drought?

Can chromosome reorganisation aid adaptation to drought?

Whole genome duplication (WGD) events, followed by reductions in chromosome number (referred to as descending dysploidy), are known to have had a significant impact on the structure and function of modern plant genomes. Despite the numerous WGD events in plant evolutionary history, many extant plant species, particularly herbaceous, self-pollinating, and annual species, exhibit surprisingly low chromosome numbers and relatively small genomes. While some explanations for genome downsizing after WGD have been proposed, the evolutionary drivers behind chromosome number reduction remain poorly understood. This project seeks to address this gap by exploring the hypothesis that reductions in chromosome number are driven by natural selection to create linkage groups that are favorable for adaptation to specific environments, particularly arid habitats. This hypothesis, initially proposed by Darlington and further developed by Stebbins, suggests that chromosome condensation may provide selective advantages by maintaining favorable gene combinations and reducing recombination rates. These effects could be particularly beneficial in species inhabiting harsh, stable environments, where maintaining a highly fit population structure is crucial. To test this hypothesis, this project explored the evolution of Nicotiana section Suaveolentes, a group of plant species that have undergone rapid radiation in Australia and display a wide variation in chromosome numbers and genome sizes. This group is particularly interesting due to its adaptation to diverse environmental conditions, ranging from mesic (moderate) to highly arid habitats. The project aimed to investigate whether chromosome condensation and associated genomic rearrangements are linked to adaptation to arid environments and rapid species diversification in this group. Understanding the evolutionary mechanisms that enable plants to adapt to extreme environments, such as arid regions, is crucial for addressing several challenges, particularly in the context of climate change. Additionally, the project has implications for biodiversity conservation, as many species are under threat due to habitat loss and environmental changes. The overall objectives of this project were: To test the hypothesis that chromosome condensation aids adaptation to arid habitats, specifically within the Nicotiana section Suaveolentes. To detect large-scale genomic variations and investigate whether genomic rearrangements cluster genes responsible for adaptation to extreme environments. To infer past population demography and recombination heterogeneity, investigating whether adaptation to extreme habitats occurred alongside significant genetic bottlenecks and to characterize spatial variation in recombination rates along chromosomes.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз