202T Poster - Population Genetics
Thursday June 09, 8:30 PM - 9:15 PM
Characterizing Mimulus guttatus adaptation to serpentine soil
Authors: Allison Gaudinier 1,2; Jessica Selby 3; Allison Rothrock 1; John Willis 3; Benjamin Blackman 1
Affiliations: 1) University of California, Berkeley, Berkeley, CA; 2) Miller Institute for Basic Research in Science, Berkeley, CA; 3) Duke University, Durham, NC
Keywords: Complex traits
Yellow monkeyflowers, Mimulus guttatus, are particularly adept at overcoming environmental stresses and can be found growing in a wide variety of ecosystems. We are investigating the molecular and phenotypic mechanisms that allow for M. guttatus to adapt to serpentine soils, a particularly harsh edaphic environment. ​​Serpentine soils have skewed Mg:Ca ratios, low levels of essential nutrients (N, P, K, Ca), increased levels of heavy metals such as Zn, Ni, Fe, and Cd that are toxic to many plants, and have poor water retention. Previous work suggests that tolerance to the complex stresses of serpentine soils is through polygenic adaptation. We are using hypothesis-generating approaches to determine the genetic mechanisms and traits selected for serpentine adaptation. Population genome resequencing of many serpentine and nonserpentine populations has revealed regions with divergent alleles. This data, coupled with transcriptome profiling in serpentine and nonserpentine conditions, has revealed strong candidate genes for serpentine adaptation. Allele specific expression analysis of reciprocal F1 hybrids will determine if differential expression of candidate genes is due to cis-regulatory difference. Further, protein structure prediction has allowed us to identify candidate genes for which serpentine and nonserpentine alleles are predicted to differ functionally. We have targeted several candidate genes for mutant analysis using CRISPR-Cas9 and will examine their functional roles. Accompanying the genomic data, we are performing phenotyping of potentially adaptive traits to define the trait differences between serpentine and nonserpentine populations. Initial results indicate that tolerance of the highly skewed ionic composition of serpentine soils likely derived in part from evolutionary adjustment of ion channel properties.