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Abstract Detail



Mechanisms underlying exceptional plant diversity across eastern Asia

Sakaguchi, Shota [1].

Genetic parallelism during recurrent serpentine adaptation in the Eurasian goldenrod in Japan.

Serpentine soils are characterized by an imbalance of soil elements and excess of toxic metals that impose obstacles for successful colonization of plants. Therefore, adaptation to the extreme soil is a fundamental process in the evolution of serpentine species. Under ecological trade-off between serpentine and non-serpentine populations, non-random mating can lead to the establishment of reproductive isolation, which sometimes results in repeated generation of serpentine adapted populations on different isolated islands of serpentine substrates. When such parallel evolution occurs in relatively short evolutionary terms, genetic variations pre-existing in ancestral populations are expected to be reused by natural selection. Yet, our knowledge is limited regarding how standing variation is selected during serpentine adaptation, in which other processes such as gene flow, drift and dispersal limitation are also involved. The scattered serpentine areas of Japan are known for high levels of plant endemism. The Eurasian goldenrod (Solidago virgaurea complex) is widespread across the country, and serpentine populations showing edaphic tolerance and early flowering habit evolved repeatedly in isolated patches. Targeting the serpentine Solidago populations and their surrounding non-serpentine counterparts, we first aimed to identify candidate genes underlying serpentine adaptation by whole genome sequencing of two ecotypic population pairs. The allelic variations at these genes were then determined for paired serpentine and non-serpentine populations in 12 locations to investigate the extent of genetic parallelism over the regional landscape. As the results of genome-wide association analysis of SNPs and soil types, 12 genomic regions scattered at nine pseudochromosomes showed significant levels of association. These regions included multiple genes encoding ion transporters (e.g. K, Ca, Mg transporters) and phospholipases, indicating the importance of ion homeostasis and signal transduction during serpentine adaptation. Genotyping at eight candidate genes revealed that derived alleles were consistently more dominant in serpentine populations. Genetic parallelism across locations was most pronounced for one Mg transporter gene. At some other genes, significant allelic differentiation between soil types was observed in more geographically isolated locations, which suggested possible dispersal limitation of serpentine adaptive variations. The allelic distributions at these candidate genes were in sharp contrast to the spatial genetic structure inferred from neutral markers. Overall, our genomic assessment suggested that serpentine adaptation has a polygenic basis in the Solidago populations, and therefore, the convergent genotypic constitution at the adaptive genes was likely shaped by recurrent selection in spite of imperfect genetic linkage and stochastic processes.


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1 - Kyoto University, Graduate School of Human and Environmental Studies, Yoshida-nihonmatsu-cho, Sakyo-ku, Kyoto, Kyoto, 606-8501, Japan

Keywords:
serpentine
Ecotype
Speciation
Japanese Archipelago
Asteraceae
Whole genome re-sequencing.

Presentation Type: Colloquium Presentations
Session: C04, Mechanisms underlying exceptional plant diversity across eastern Asia
Location: /
Date: Tuesday, July 20th, 2021
Time: 11:30 AM(EDT)
Number: C04006
Abstract ID:580
Candidate for Awards:None


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