The Basic Science Research Concept

“So are you trying to make plants more defended?”

This is often the first question I encounter when I share my research questions with anyone that does not spend their work life thinking about plants. Before the conversation can get much further, I find it helps to introduce the difference between basic science research and applied research.

Both are important, but it is easier for people to connect with applied research: research designed to improve the way humans live. However, many of the solutions we use today came as a result of discoveries from basic science research: research designed to understand the way something works for the sake of understanding.

Like what?

PCR: the technology that lets us duplicate tiny amounts of DNA, was only possible because a scientist was curious about how acidic and hot Yellowstone hot springs could be for bacteria to survive. Bacteria flourishing at high temperatures have DNA too, and the enzymes that could replicate DNA despite the heat were eventually extracted and were able to withstand the hot temperatures in PCR.

Efficient building design: scientists were curious about the structure of termite mounds, which can maintain a constant temperature despite the heat of the desert. The results from these studies were used to construct a building in Zimbabwe (The Eastgate Centre) that uses 90% less energy.

Velcro, the ubiquitous adhesive found on light-up shoes, was inspired by plant hook-shaped hairs.

And the list goes on. The moral of the story is that technology gets along well with natural selection, but first we have to understand how it all works.

My research goal is to understand how plant-insect interactions change as a result of the chemistry within the plants that have a symbiotic relationship with nitrogen-fixing bacteria. I spend my time at my desk wondering about how and when plants will use their resources to make the stuff that protect them- either directly by making poisonous chemicals, or indirectly, by sending volatile compounds into the air to communicate with the predators of their attackers.

Instead of trying to get plants to do anything, my goal is to understand what they actually do on their own- to understand the unknown aspects of their biology.

Do these bacteria play an important role in the food web by altering plant-insect interactions? My research will let you know.

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Plants with Benefits

Maintaining relationships, even great ones, can be challenging.

Some plants juggle multiple relationships ALL of the time.

Think of an organism that does something helpful for a plant. Bees, hummingbirds, and other pollinators may come to mind. But plants also recruit toucans, black bears, and other seed dispersers as well as predatory insects such as ants and wasps for defense.

And then there are microbes.

My goal for this research paper was to show how one microbe in particular, nitrogen-fixing bacteria called rhizobia, can alter a plants’ entire network of relationships—from the bottom-up.

Rhizobia live inside nodules on plant roots in a tight-knit symbiotic relationship, exchanging fertilizer for sugars from photosynthesis. Plants that form this relationship benefit immensely from the nitrogen, but providing sugar in return can tax the plant.


Plants also use their homemade sugar to secrete extrafloral nectar. Nectar typically attracts pollinators, but in the case of extrafloral nectar, plants produce nectar to attract ants, which patrol their sugar source like bodyguards. By evicting intruding bugs attempting to feed on the host plant, extrafloral nectar can be an effective indirect plant defense…

…as long as the ants show up to do their part.


But the key result from our paper is that ants are less attracted to plants that have nitrogen-fixing rhizobia in root nodules belowground. Keep in mind- the ants and bacteria do not interact directly. What connects ant to bacteria?

The plant between them.

Plant chemistry changes when plants form symbiosis with rhizobia. Plants with nitrogen-fixers make more of the nitrogen-based traits, protein and cyanogenesis. Surprise. But these plants also secrete less sugary nectar, therefore attracting fewer ants.

Even in the plant world, some relationships can be more demanding than others.

How do rhizobia cause plants to compromise their ant relationships?

It could be that rhizobia demand so much sugar to keep the nitrogen flowing that the plant’s excess sugar supply is exhausted, leaving little to serve as ant lures. Alternatively, why would plants that get a constant supply of nitrogen to make cyanide need to attract ants anyways?

Either way, we now know rhizobia can change plant relationships with ants.

But why would that matter?
Ants are everywhere- so are rhizobia. Both play important roles in how ecosystems function, but the fact that they can indirectly affect one another may have strong and widely overlooked impacts on plant ecology.

© Adrienne Godschalx (adrg@pdx.edu) August 19, 2015