Lessons from your parents: “Fool me once, shame on you. Fool me twice, shame on me” – Randall Terry.

This post is by UW faculty Cynthia Chang and Thelma Madzima, research tech Colin Feng, and undergraduate researcher Jackelyn Garcia

“I told you so” – All parents?

Can the lessons from your parent’s experiences be passed on to you for your benefit, and if so, how?

In many organisms, the memory of our experiences often influences our behavior and how we respond to similar situations in the future. In humans, these ‘learned’ lessons are often passed on verbally from one generation to the next. (Sometimes, no matter what our parents tell us, we have to experience things for ourselves). However, in some organisms like plants, life lessons and behavior are not ‘verbally communicated’, but rely on other methods so that clues of past experiences are passed on to offspring.

In living organisms, memory information can be passed on from one generation to the next at the molecular level; through signals added on top of DNA, referred to as ‘epigenetic modifications’ (Greek for epi = on top or above. Therefore, on top of genetic information). Epigenetic modifications (such as DNA methylation) can be inherited, are reversible and can influence phenotype or how an organism develops. Epigenetic modifications can also be induced by the environment, therefore, by studying the inheritance of epigenetic signals, we can understand how the environment experienced in one generation (parents) can impact developmental responses in the offspring. Thus, epigenetic modification may prove to be an important signal to understanding how species remember and respond to a rapidly changing climate (Donelson et al. 2017).

Climate change: “It’s getting hot in her(r)e” – Nelly

Current climate change models predict greater periods of drought as well as a more variable environment, both of which will drive the evolution of how plants respond to changing environmental conditions (Jump and Penuelas 2005). Our project focuses on determining if plants that experience high environmental stress (drought) pass on molecular signals (epigenetic modifications) to their offspring which allows the offspring to learn from their parents, and better adapt to a variable environment.

To do this, we are using the model plant Arabidopsis thaliana, a fast-growing, primarily selfing plant. As part of our experimental design, we will collect physiological and epigenetic data from Arabidopsis plants exposed to different stresses over multiple generations. In the first 3 generations, we will expose half of our plants to high-drought conditions, and the other half to normal conditions (low-stress; non-drought). Offspring seeds will be collected from each plant and planted in the same treatment their parent experienced. In the fourth generation, we will determine if these life experiences are inherited. We will compare historically stressed plants to non-stressed plants, when grown in either a low, high, or variable water stress environment. We hypothesize that historically stressed plants will grow better than non-stressed plants when grown in a high or variable water stress environment. However, it is also possible that plants have to ‘learn for themselves’ each time.

What’s in it for me?”

This research will provide insight into how a plant population’s past experiences can help or hinder its ability to adapt to a rapidly changing environment. Understanding how plants will respond to climate change is a major motivation for our whole research team.

“The molecular mechanisms of epigenetic inheritance are particularly relevant to all plants, especially in agriculturally important plants. But first, it’s important and more feasible to study these mechanisms in a model plant like Arabidopsis thaliana”. – Thelma Madzima

“I am excited to see how the epigenetic modifications will affect Arabidopsis in the future generations of this project. More specifically, I want to see what genetic differences do stressed plants have compared to unstressed (if any) and how that impacts their ability to respond to stresses.” – Colin Feng

With an interdisciplinary team, we are able to tackle this research question with our different areas of expertise.

Jackelyn Garcia, 2nd year undergraduate researcher at the University of Washington-Bothell, watering the first generation of experimental plants.

“Understanding the evolutionary implications of epigenetics is an exciting way to bridge the gap between molecular biology and ecology.” – Cynthia Chang

Finally, this Beacon research is providing first-hand research experience to young undergraduate researchers. Jackelyn Garcia, a 2nd year UW-Bothell aspiring Biology major has dedicated her time to understanding the phenotypic (trait) patterns of the plants. She hopes to use this research to connect her coursework to real research, and learn more about evolution, ecology, and genetics.

Scientific experience and inheritance

This research is being conducted in collaboration with the undergraduates phenotyping Arabidopsis knockouts (unPAK) network (http://arabidopsisunpak.org/). unPAK is a network of undergraduate research institutions working towards to goal of understanding the relationship between genotype and phenotype, using Arabidopsis. In addition to answering our own research questions, the plants grown in our experiment will provide data for this growing database of unPAK genotype-phenotype data. Both Assistant Professors are particularly excited to incorporate this research in their undergraduate Investigative Biology courses with the hope of adding to our growing understand of how plants can adapt to climate change and the molecular signals that are transmitted, and inspiring new researchers to tackle this complex problem.

Literature Cited

Donelson, J. M., S. Salinas, P. L. Munday, and L. N. S. Shama. 2017. Transgenerational plasticity and climate change experiments: Where do we go from here? Global Change Biology.

Jump, A. S., and J. Penuelas. 2005. Running to stand still: adaptation and the response of plants to rapid climate change. Ecology Letters 8:1010-1020.

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