IMAGiNE: The genetic, developmental, and physiological mechanisms of plant local adaptation to oceanic salt spray

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A fundamental goal of biology is to understand how and why biological organisms evolve, from the level of genes to ecosystems. This research explores these evolutionary processes by studying the yellow monkeyflower, Mimulus guttatus, and how it adapts to oceanic salt spray. For a long time, scientists have known that salt spray influences which plant species can survive near the ocean. However, little is known about how plants evolve adaptations to live in coastal areas in the first place. The research focuses on understanding how coastal monkeyflower populations evolved to 1) avoid salt spray by remaining short and not flowering during windy periods, 2) resist salt spray by preventing it from entering plant tissues, and 3) tolerate salt spray by transporting salt to parts of the plant where it will cause the least amount of damage. Overall, this research should uncover multiple dimensions of these adaptations from the gene to the population level. The research will also result in the development of new tools for genetic engineering of monkeyflowers. Ultimately, the work will expand understanding of plant evolution and aspects of plant resilience in challenging environments, with potential applications for agricultural crops. The results of the research will be incorporated into educational materials, including a comic book and audio podcasts. To evaluate these educational materials, the investigators are working directly with teachers and hundreds of low-income minority high school students in Flint, MI through hands-on inquiry-based research.The proposed research aims to understand the genetic, developmental, morphological, and physiological mechanisms of local adaptation of the coastal perennial ecotype of Mimulus guttatus to oceanic salt spray. The extensive tools available for M. guttatus will facilitate studies of adaptation for multiple genes within gene networks. The research is divided into three aims, each of which is focused on a key component of salt spray adaptation: avoidance, resistance, and tolerance. Aim 1 is focused on understanding the mechanisms of locally adaptive salt spray avoidance by the coastal ecotype through the evolution of a compact growth form and a late-season flowering time. The research will test whether the developmental divergence between coastal and inland ecotypes underlying salt spray avoidance is caused by the evolution of genes within the gibberellin hormone gene network. Aim 2 will evaluate the role of morphological divergence between coastal and inland ecotypes in resistance to salt spray entry into plant tissues once it has landed on aerial plant organs. Aim 3 will evaluate the genetic and physiological mechanisms of salt spray tolerance once salt has entered aboveground plant tissues. Sodium transport at both the level of entire leaf organs and individual leaf cells will be examined to test the hypothesis that the coastal ecotype has higher tolerance by pumping sodium out of the cytosol into the apoplast and vacuoles. Overall, the research will lead to an increased understanding of how fitness in stressful environments is an emergent property of multiple complex organismal adaptations.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.