Overview

Project Highlights:

  • Identify molecular mechanisms for adaptation to extreme environments in polyploid Erythranthe guttata (monkey flower plant) populations
  • Determine extent of preadaptation in diploids to polyploidzation and environmental stresses using genotyping/phenotyping approach
  • Perform salt stress experiments on multiple Erythranthe guttata diploid and autotetraploid populations and assess physiological response

Overview

The monkey flower plant (Erythranthe guttata, formerly Mimulus guttatus) is an out-crossing, water-loving species that is largely distributed throughout North America in both diploid and autotetraploid populations. E. guttata has adapted to the internal stress of whole genome duplication that may have conferred an advantage for external success as these plants thrive on toxic serpentine soils as well as soils with high salt conditions. In addition, E. guttata is used as an ornamental species grown in gardens due to the abundance of bright yellow flowers (see Fig. 1), such that in Victorian times plants were brought back to the UK and have now widely established themselves. In particular, we have recently discovered a new species of tetraploid E. guttata in the Shetland Islands that appears to have arisen through whole genome duplication of the invasive diploid species (Simon-Porcar et al. 2017). This NERC CENTA proposal is curiousity driven but aims to elucidate the adaptability of polyploid plants to challenging environmental stressors.

We are currently using next generation sequencing to determine if the diploids and autotetraploids are genetically similar and whether standing variation in the diploids provided pre-adaptation material for meiotic success in whole genome duplication. In this CENTA PhD project we will assess the performance of diploids and autotetraploids (collected from UK and Western USA populations) to environmental stresses such as high salt and toxic metals as well as meiotic adaptation to polyploidy. We will incorporate genomic data obtained in collaboration with Dr Levi Yant (University of Nottingham) to identify causal genes for adaptation, similar to the approach that we have previously employed in Arabidopsis arenosa (Yant et al. 2013).

Figure 1. Characteristic flowering stage of the tetraploid ‘monkey flower plant’ (left) and panels showing meiotic metaphase I chromosomes from diploids (top right), meiotically unstable plants (middle right) and meiotically stable plants (bottom right) collected from California, suggesting a segregating genetic component.

Methodology

The project will include subjecting plants from five E. guttuta diploid and five autotetraploid populations to various levels of salt conditions and measuring performance such as growth, weight, number of flowers etc. We will test for segregation of adaptive alleles within the population, first by phenotyping and then second using next generation sequencing to determine which alleles associate with salt tolerance. We wil also phenotypically screen these plants for meiotic stability using chromosome spreads at meiotic metaphase I (see figure 1). We have already identified a candidate gene (ASY1) to test for allelic variability and segregation within these populations.

Training and Skills

The student will be trained in: cytological chromosome analysis and fluorescence microscopy; molecular techniques for genotyping plants; bioinformatic procdeures for analysing next generation sequencing and physiological experimentation (with potential ionomincs at the University of Nottingham).

Timeline

Year 1: Obtain E. guttuta seeds from collaborators and perform physiological experiments on plants including high salt exposure. Perform cytological analysis to determine meiotic stability to polyploidy.

Year 2: Use a bioinformatic approach to identify candidate genes from data derived by next generation sequencing at the University of Nottingham. Perform molecular analysis to clone candidate genes (alleles) and then test for segregation in selected populations.

Year 3: Characterise candidate genes (alleles) by creating isogenic lines and performing physiological and cytological experiments.

Partners and collaboration (including CASE)

We will collaborate with Dr Levi Yant and Professor David Salt (University of Nottingham) as well as Dr Mario Vallejo-Marin (University of Stirling).

Further Details

https://www2.le.ac.uk/departments/genetics/people/dr-james-higgins-2