Author: veroiriart

Herbicide drift impacts the growth and flowering of wildflowers in a synthetic plant community

On By veroiriartIn PhD LifeLeave a comment

            Each year, billions of pounds of pesticides are used to improve growing conditions for crops in the U.S., of which herbicides account for more than half of total usage rates. But what happens when herbicidal chemicals don’t stay in their intended area? How are plants and animals impacted when an herbicide infiltrates their habitats from neighboring agricultural fields? These are some of the questions I sought to address in the first chapter of my PhD thesis that was just published in the journal Annals of Botany. In particular, my research advisor, Dr. Tia-Lynn Ashman (University of Pittsburgh, Pittsburgh, PA), collaborator Dr. Regina Baucom (University of Michigan, Ann Arbor, MI), and I were interested in knowing how different wildflower species that typically live in the margins of agricultural areas respond to pollution from the herbicide dicamba, which has risen in use exponentially over the past several years and has been linked to numerous cases of ‘drift’ pollution, which occurs when herbicidal particles are taken up by the wind and carried to non-target areas at low concentrations. We focused on wildflowers because they make up diverse plant communities that are important food sources for a variety of animals, especially pollinators like bees. Therefore, by characterizing the effects of drift pollution on wildflowers, we also aimed to make predictions about how pollinators are indirectly impacted.

Experimental set-up. Twenty-five species of wildflowers were randomly distributed across benches in the University of Pittsburgh greenhouse.

            To address our research questions, we created two ‘synthetic’ communities of wildflowers in the greenhouse at the University of Pittsburgh, each comprised of 25 species that we previously identified as common inhabitants of agricultural margins in the U.S. We treated one community with an extremely small dose of dicamba to mimic what plants would be exposed to when drift pollution occurs and left the other community unexposed as a control. We tracked the growth and flowering of all plants by recording data on leaf and flower production and weighing samples of dry leaves, stems, and flowers to make size estimates. Using data on flowering, we constructed ‘networks of co-flowering interactions’ for the drift and control community, which show how frequently species overlap in flowering over time.

Signs of leaf cupping and stem damage caused by treatment with dicamba drift

            Through this experiment, we saw that there was considerable variation in how wildflower species responded to drift pollution. Many were sensitive and showed significant signs of damage immediately after drift treatment, such as stem twisting and leaf ‘cupping’ (when leaves fold inward to make a cup shape). A quarter of species were also negatively impacted by drift in terms of growth: plants of these species treated with drift were substantially smaller than their controls. Still, most species ultimately grew to comparable sizes regardless of the whether they were treated with drift or not, and a couple even grew to be significantly larger when treated with drift, possibly because the dicamba herbicide’s mode of action is to mimic the plant growth hormone auxin. The most interesting finding from this study, however, was how patterns of flowering changed. We found that most species were affected in terms of flowering time by drift—they either flowered significantly later or earlier when treated with drift than the control or flowered for shorter or longer periods of time throughout the duration of the six month-long experiment. Ultimately, this variation in flowering responses across wildflower species led to pronounced differences in the structure of coflowering networks between the control and drift community. In particular, the drift network was significantly less connected than the control, meaning that species tended to overlap in flowering less frequently. Additionally, groups of species that were more likely to overlap in flowering with each other were composed differently in the control network than the drift network. Altogether, these results suggest that herbicide drift has potential consequences for wildflowers in terms of changing which species are competing for pollinators at a given time, but also for pollinators in terms of shifting how many and which kinds of floral resources (since these are determined by which species are flowering) are available to them.

Coflwering networks of greenhouse wildflower communities that were treated with herbicide (dicamba) drift or a control solution. Each circle is a wildflower species (labels show abbreviated species names) and links between species indicate coflowering interactions (they overlap in flowering time). Thicker links mean longer periods of overlap between species. Different colors show which groups of species are more likely to overlap in flowering with each other than with others. Image was adapted from Figure 3 in Iriart et al. 2022.

            Overall, this study was important for showing how even very low levels of herbicide exposure can have profound effects on the growth and flowering of many wildflower species and also potentially the pollinators that would visit them. The next step we would need to better understand the consequences of drift pollution for wild plants and animals is to transition from ‘synthetic’ communities in the greenhouse to real ones in field conditions.

Yerba maté (Ilex paraguariensis)

On By veroiriartIn Love of FloraLeave a comment
Yerba maté with a traditional gourd and bombilla

            This month, I made the long trek to Buenos Aires, Argentina to attend an important family event. Amidst all the visits with my aunts, uncles, and cousins, I was reminded of a key component to Argentinian culture that I never before thought about through a botanical lens: yerba maté.

            Yerba maté is a strong-tasting herbal tea that’s made by steeping dried leaves of a subtropical, evergreen plant (Ilex paraguariensis) with hot water. The first thing you notice after drinking maté is its striking bitter taste, and the second is its ability to wake you up! At 78 mg of caffeine per cup, maté has almost as much caffeine as coffee (85 mg per cup).

Typically, maté is prepared in a gourd and drunk through a bombilla, a metal straw that has a filter at the end to allow the tea to pass through but not the leaf chunks. The Guaraní people who lived in what is now Paraguay were the first to make maté prior to the European colonization of South America, and they did so using natural gourds made from the calabaza plant (Lagenaria vulgaris). Interestingly, ‘calabash’ gourds are still the most common maté gourds, and the word ‘yerba maté’, which is a mix of Spanish and Quechua, literally means “herbs from the calabash.” Today, maté is still heavily consumed in Paraguay as well as in Argentina (the world’s largest maté producer), Uruguay, and Brazil.1

Yerba maté plant (I. paraguariensis; left) and calabash (L. vulgaris; right)

            What this long history of maté meant for me was a strong association between maté and my Argentinian relatives. In fact, whenever I think about my maternal aunts, two religious maté drinkers, I imagine them with gourds readily in their hands. Because unlike in the US where coffee or caffeinated tea is generally reserved for the morning hours, many Argentines like my aunts drink maté continuously throughout the day. In particular, drinking maté is often a social event, where friends pass it around while conversing during their leisure time. Unfortunately for me growing up, my tastebuds did not immediately acquire a taste for maté, so I would often opt to drink a soda with my family over sharing maté on these occasions, but now that I’m older I can appreciate more the healthful benefits of this rich drink. For instance, besides caffeine, maté is also packed with many antioxidants and nutrients that have anti-inflammatory and cholesterol-lowering properties.2

            If you’re interested in trying maté in the States, the company Guayakí has taken a modern approach to producing it with wide success: they sell yerba maté sparkling cans, energy drinks, tea bags, as well as packages of loose leaves to make it the traditional way. Like with coffee, there are many ways to sweeten the bitter taste of maté by adding sugar and cream, i.e. making a ‘maté latte. Give it a try and see if you can enjoy the health and social benefits of maté like an Argentine!

References

1Heck, C. and De Mejia, E. (2007), Yerba Mate Tea (Ilex paraguariensis): A Comprehensive Review on Chemistry, Health Implications, and Technological Considerations. Journal of Food Science, 72: R138-R151. doi:10.1111/j.1750-3841.2007.00535.x

2Gawron-Gzella A, Chanaj-Kaczmarek J, Cielecka-Piontek J (2021). Yerba Mate-A Long but Current History. Nutrients, 13(11):3706. doi: 10.3390/nu13113706.

The Power of a Post-Vacation Glow

On By veroiriartIn PhD LifeLeave a comment

            Many people believe that getting a PhD is like an extension of the college experience: you take classes with people that have similar interests as you, you live on or near a college campus, and you still eat microwaved ramen for dinner. While all of these things are true, there are important differences between undergrad and PhD student life that, left unnoticed, could be harmful to your chances of success or even your mental health. One of these is the need to schedule your own time off from the academic grind.

            As an undergraduate, colleges or universities will schedule time off for you: along with several holidays, you typically get at least one long break in the fall, spring, and summer where classes are not in session. And while many students take on additional courses, jobs, or internships during these longer breaks, they are still often seen as opportunities for students to step away from their usual coursework. As a PhD student, you unfortunately don’t get these same pre-determined breaks. In this way, a PhD is a lot like that typical 9 to 5 job: you are expected to work on your thesis year-round and, outside of holidays, it is up to you to discuss with your advisor when you get time off. For the often overly-ambitious and probably overly-anxious PhD student like me, this set-up could quickly turn into a situation without any real vacation time at all before you even realize it. However, this past month, I took a much-needed long break away from my PhD to travel to Europe on my honeymoon, and I returned with a new appreciation for the benefits of feeling that post-vacation glow.

More energy and motivation

On average, it takes 4-6 years to earn a PhD; in my program, it takes most people at least five. This is a long time to dedicate to one research topic! So, like in many other jobs, it can be very easy to experience burnout as a PhD student, especially once you’ve reached your third or fourth year as I have. In coming back from my long break, however, I was surprised to see how eager I was to return to my thesis project. While I greatly appreciated being able to sight-see and relax on vacation, by the end of it I felt that my brain was ready to be stimulated again with new, complex problems to solve. My mind also felt much more rested physically – the lack of any pressing deadlines meant that I could get a full-night’s sleep every night. As a result, I came back to the lab feeling energized to complete the tasks that I now also had much more motivation to tackle.

A boost of happiness

Although a PhD student’s work schedule varies depending on many factors such as their personal preferences, advisor(s), and home institution, it is pretty universal that a PhD requires many hours of work per week. In my experience in biology, students work at least 40 hours per week and the hours fluctuate a lot depending on the status of their experiments. An unfortunate consequence of this is that personal relationships can suffer. In my home, my partner also has a demanding full-time job, so sometimes it feels like we end up spending little time together in a seven-day work week, despite the fact that we live together. Our vacation, however, was a time for the two of us to spend our undivided attention on each other and make our bond stronger. In addition, all the hilarious stories we collected during our travels were really fun to share with my labmates when I got back to work, so that helped me bond with them too and made me all the more happier to be in the lab again.

Closing thoughts

While it may seem obvious that taking time off from work is beneficial, many PhD students go too long without a break, worrying that it will negatively impact their productivity or cause them to fall behind. In reality, however, I have found that taking a long vacation has helped me feel refreshed and happy to continue my thesis work. The science seems to support the physical and psychological benefits of vacation time too: people who took vacations more frequently were less likely to have severe complications from heart disease or develop depression than those who vacationed infrequently. In the future, I won’t wait for a big life event like my honeymoon to take a break from all the hard work and rigor to instead spend quality time with my partner or friends, and I hope you won’t either.

Wolf or friend? Wild Lupin (Lupinus perennis)

On By veroiriartIn Love of FloraLeave a comment
Wild Lupin in Maine. I took this photo during field work as an undergraduate research assistant at the University of Massachusetts Boston.

I fell in love with wild lupin (Lupinus perennis) during one of my first research experiences as a college student. I was doing a summer fellowship with the National Science Foundation at the University of Massachusetts Boston, where I was working with a lab that studied marine ecology.

The lab was interested in tracking marine mussels, which are ecologically and economically important to the New England area, by comparing the chemistry of these animals’ shells to that of the water at different coastal sites. Our field work involved donning wet suits and driving a small motor boat into the ocean to collect water samples, and at times it was bitter work. Of course, I wasn’t yet a plant biologist back then – I was trying to explore my interests rather – but I still distinctly remember being cheered up by the sight of the beautiful blueish purple flowers of wild lupin that were in bloom at several of the sampling sites we visited. And now, after gaining some botanical knowledge through my current research, I learned that there is a lot more to appreciate about this native wildflower than just its beauty.  

Wild lupin has several special abilities that make it biologically interesting. For example, while it’s thought that wild lupin got its name from the Latin word for wolf (‘lupus’), because people perceived the plant’s ability to grow in poor conditions as a sign of predation, as if lupin was taking away nutrients from other plants, in reality wild lupin acts more like an ecological ally. Similar to the red clover plants I study, wild lupin actually enhances the quality of the soil it lives in by forming a symbiotic relationship with a particular kind of soil bacteria called rhizobia. In this relationship, rhizobia fix nitrogen, which is essential for plant growth, by transforming the nitrogen that’s present in the air into different forms like ammonia, nitrite and nitrate that plants can access and use to grow. This process of biological nitrogen fixation obviously benefits wild lupin directly and gives it a special advantage, but it also increases the local nitrogen content which benefits other plants.

Another interesting trait about wild lupin is its ability to ‘communicate’ with pollinators. Lupin produces a lot of protein-rich pollen that bees, especially bumblebees, are attracted to. However, if a wild lupin flower has already been visited by a bee, the center of the flower will change color from white to purple, and the bees have learned that this is a signal to avoid that flower. Basically, the flower is saying in a way: “don’t visit me, go find fresher flowers that have more pollen.” Overall, this adaptation benefits both the bee and the plant because the bee uses less energy in finding pollen and the plant increases the likelihood that its pollen gets spread around to make seeds.

As a college student trying to figure out her career path, I never would’ve guessed that the plant I stopped to admire and photograph during a summer internship would turn out to have such obvious connections to my future work studying biological nitrogen fixation and pollination ecology. What plants have you formed connections with at a young age?

Sources

“Plant database: Lupinus perennis.” Lady Bird Johnson Wildflower Center. 27 Sept. 2022. https://www.wildflower.org/plants/result.php?id_plant=lupe3

Weiss, M. R. Ecological and evolutionary significance of floral color change. 1992. University of California at Berkley, PhD dissertation.

Delving into the Microbial World

On By veroiriartIn UncategorizedLeave a comment

This summer, I worked on some science that was totally different from what I’m used to. Rather than tracking seed germination or collecting data on plants given different herbicide treatments in the greenhouse, I was cultivating and maintaining a diverse array of microorganisms in the lab, visualizing them under the microscope, and characterizing their physical appearance, metabolisms, and genetics. This change was brought upon by the Microbial Diversity Course (MD 2022), which I was extremely fortunate to be a part of for the last six weeks at the Marine Biological Laboratory in Woods Hole, MA. Originally, I applied to this course because I wanted to gain more microbiology experience that I could then apply to my PhD research on plant-bacteria interactions. I did not expect, however, to become completely enamored with the microbial world. I learned so much not only from the course material but also from the brilliant people I interacted with, such as the course directors, Rachel Whitaker (University of Illinois) and Scott Dawson (UC Davis), teaching and course assistants, and, of course, the other 19 scientists who were students alongside me. Here are some highlights from what I learned during this unique experience at ‘microbiology bootcamp.’

Microbes can influence our environment in obvious ways

Pink sand at Great Sippewissett Marsh, Falmouth, MA. Photo credit: Sarah Guest (MD 2022 TA)
Microbial mat layers. Great Sippewissett Marsh, Falmouth, MA

In the first week of the course, we visited the Great Sippewissett Marsh, a large tidal salt marsh near Woods Hole in Falmouth, MA, to collect samples that we would later use to cultivate microbes from. In one part of the marsh, you could see long stretches of eye-catching pinkish-purple sand. As I learned from environmental microbiologist Elizabeth Wilbanks (UC Santa Barbara) who specializes in studying microbes from this region, what gives the sand this beautiful color are microbes called purple sulfur bacteria. They are so-called because of their purple pigment and their ability to metabolize sulfur, which is highly abundant in this ecosystem. In other parts of the marsh, you can also find ‘microbial mats’, which look like thin leather rugs on the sand. If you dig up an inch or two of a microbial mat, you will see an obvious gradient of colors that are also caused by microbes. The top brownish-green leathery layer is composed of cyanobacteria. It’s followed by a pinkish-purple layer of purple sulfur bacteria, a greenish-grey layer of green sulfur bacteria, and black and grey layers of iron sulfide, the product of microbial sulfur metabolism.

To know it is to grow it

We performed a total of 24 ‘enrichments’ (techniques to enhance the growth of a particular type of microbe from a sample) to study different kinds of microbes in the lab. One of the coolest groups of microbes we grew were bioluminescent or light-emitting bacteria. These are usually members of the Vibrio and Photobacterium genus and are surprisingly easy to cultivate from seawater, sediments, and surfaces of fish and other marine life. In general, the purpose of bioluminescence for marine bacteria is unclear, but it’s known that some produce light as a result of a symbiosis with marine animals: the animals provide nutrients and habitat to the bacteria in exchange for defense, prey attraction, or other services. Bobtail squids are a cool example of an animal that participates in this special symbiosis. Other interesting microbes that we enriched for were spirochaetes – spiral-shaped bacteria that swim quickly in a corkscrew-like motion, thiosulfate-oxidizing bacteria – bacteria that live in oxygen-sulfur gradients and can oxidize thiosulfate (S2O32-) in their metabolism, microbial eukaryotes such as amoeba and ciliates (unicellular organisms with hairlike structures called cilia that help them swim and capture food), and bacteriaophages – viruses that infect bacteria.

Microbial Diversity spelled out using bioluminescent bacteria (Vibrio spp.). Photo credit: Germaine Smart-Marshall (MD 2022 CA)
Thiosulfate oxidizing bacteria sunset. Knowing that the product of sulfur oxidation is sulfuric acid, we enriched for these microbes on phenol red media, which changes color from red-purple to yellow when the pH drops, indicating the media became more acidic.

Spirochaetes. Photo credit: Malique Bowen (MD 2022 student)

Microbial eukaryotes are cute but mighty

Measuring ciliate speeds from microscope footage using the TrackMate tool in Fiji

In the last two weeks of the course, we completed individual ‘mini’ projects to research a scientific question of personal interest within Microbial Diversity. For my project, I wanted to work with a group of aquatic microbial eukaryotes called ciliates because I found it fascinating how different they could look and swim, and also they are pretty cute. When the father of microbiology, Antione van Leeuwenhoek, called microbes ‘animalcules’ meaning ‘little animals’, he was pretty spot on in the case of ciliates. So for my research question, I was interested in determining how tolerant different types of ciliates were to relevant environmental stressors: copper, lithium, and sulfur. Copper and lithium are common sources of heavy metal pollution in aquatic ecosystems. For instance, copper is often leached into water from antifouling paint used on boats, and lithium is used in batteries to power many electronics, including electric vehicles. Additionally, ciliates that inhabit unique places like the Great Sippewissett Marsh live in highly sulfuric environments, but it’s unknown what range of sulfur they are tolerant to or if there is a limit to their sulfur tolerance. To perform these tests, I recorded movies under the microscope of four different types of ciliates that I isolated from the Great Sippewissett Marsh after they had been exposed to different concentrations of each stressor for eight hours. Then, I used the computer software Fiji to analyze the movies and measure how ciliate swimming speed was impacted by each condition. I expected that ciliate speed would slow down as the concentration of each stressor increased, and the tolerance limit of each ciliate could be identified by the concentration that completely inhibited movement. Ultimately, the timeline for the project was too short for me to come up with conclusive answers, but I did find some evidence that the ciliates differed in their tolerance to copper and lithium. Most surprising was the finding that one ciliate type could withstand 63 mg/L of copper (II) sulfate, which is a level of copper that not only killed all other ciliates but also totally changed their shapes. Since ciliates are important food sources at the bottom of aquatic food webs, it would be interesting to see how this striking variation in copper tolerance would impact other organisms that feed on them and the broader ecosystem.

Different ciliate types used in my mini project. I differentiated them based on physical characteristics, i.e. ‘morphotypes’. Images were taken in DIC at 40x.
After eight hours of exposure to 63 mg/L copper(II) sulfate, ciliates became rounder and they stoped swimming, except for ciliate type ‘A’ which seemed capable of withstanding this high level of copper.

There is still so much to discover!

Although the Microbial Diversity course taught me so much about the different microorganisms that have been found in nature, it also taught me that there are way, way more microorganisms that we do NOT know about. Actually, the numbers are mind-boggling. In the ocean, there are 100 million times as many bacteria as there are stars in the known universe. If you picked up a teaspoon of soil, there would be about 1 x 109 bacteria, which is roughly the same number of humans that currently live in the whole continent of Africa. And if all the viruses on earth were laid end to end, they would stretch for 100 million light years (see this Nature article for these astounding estimates and more). Overall, it’s estimated that there are upwards of one trillion microbial species on earth, and we have still to discover 99.999% of them. So, while we are learning more and more that microbes can have strong impacts on human health and the environment, there is still so much that is unknown about microbial diversity. Thanks to the Microbial Diversity course, I feel much more confident in my abilities as a plant biologist turned microbiologist and look forward to making new discoveries in this microbial world of ours.

Promoting pollinator awareness in Pittsburgh

On By veroiriartIn Science OutreachLeave a comment

Pollinators are so important for the health of plants and people alike: it’s estimated that as much as 88%1 of the world’s flowering plants depend on animal pollinators, including about one-third of the world’s agricultural crops that we use as food2. This month, I participated in two awesome outreach events to promote pollinator awareness in Pittsburgh.

 June 5th – Bioblitz, Phipps Conservatory and Botanical Gardens

For those who have never been, Phipps is magical. Not only do they have an amazing diversity of plants on display, but the conservatory does an excellent job of making you feel like you’re passing through different worlds as you move from one exhibit to another –one minute you’re in a tropical rainforest in Hawaii, the next you’re in a beautiful, temperate Japanese courtyard.

On this occasion, however, I was not at Phipps as a lucky visitor, but as a scientist at work. Members of my lab and I were leading an exhibit for their annual BioBlitz and Family Fun Festival to talk to the public about plant-pollinator interactions. For the event, I took some sturdy pieces of cardboard (that otherwise would have been thrown away) and used them to create plant and pollinator-themed boards with holes cut out so people could stick their faces through and take photos. It was a big hit with kids, of course, but adults also had fun seeing their children look adorable as little bees and flowers!

After getting a ‘pollinator selfie’, many visitors also played our plant-pollinator matching game, where they tried to match different plant species with their co-evolved pollinator partner. We gave tips along the way by describing different known ‘pollinator syndromes’ or sets of traits that plants typically have to attract a certain type of pollinator or, for pollinators, to better collect floral rewards (pollen and/or nectar) from a certain type of plant. While people found it relatively easy to match plants with bee or butterfly pollinators, the act of trying to match plants with lesser-known pollinators seemed to pose more of a challenge. For instance, people were often stuck on what pollinates the plant that makes the world’s largest flower (Rafflesia arnoldii), but many were able to get it right once they learned that the flowers have a terrible, rotting smell, which helps attract its fly pollinators.

Overall, we had a blast interacting with the visitors at BioBlitz and sharing our knowledge and research about pollination. Especially now that it’s summertime, it’s common to see all kinds of pollinators hard at work collecting pollen and nectar. We hope that our discussions were able to help the community appreciate these little critters a little more for the key service they provide us and the planet.

June 24th – Everything but the B’S with the University of Pittsburgh Office of Sustainability

Did you know that each year there is a national pollinator week to celebrate and raise awareness about pollinators? For this year’s Pollinator Week, I partnered with the University of Pittsburgh’s Office of Sustainability to put on a virtual lunch and learn called ‘Everything but the B’S, where we took the spotlight away from the types of pollinators that people generally know best (bees, butterflies and birds) and shined it on the unsung heroes of the pollinator world: flies, moths, wasps, Chiroptera (bats), ants, and beetles.

As people were obviously joining us during their lunch hour, we focused on pollinating interactions between plants and non-b pollinators that contribute significantly to the making of foods that many people enjoy on a daily basis, such as: pollination of cacao trees by small midges that ultimately gives us chocolate, or that of the Musa plant and bats which leads to wild bananas, or interactions between hoverflies and strawberry plants which new research3 has shown can produce high numbers of commercial-ready fruits. But we also discussed how non-b pollinators are important for supporting the conservation of diverse wildflowers around the world, such as plants that require night-time pollination by moths and bats, the several hundred orchid species that specialize on wasp pollination, and the beautiful magnolia trees that have been pollinated by beetles for millions of years. If you’d like to see the event for yourself, or learn more about sustainability in general, you can check out the Office of Sustainability’s YouTube channel.

How will you celebrate pollinators this year?

References

1 Ollerton, J., Winfree, R. and Tarrant, S. (2011), How many flowering plants are pollinated by animals? Oikos, 120: 321-326. https://doi.org/10.1111/j.1600-0706.2010.18644.x

2 Klein, A. M., Vaissière, B. E., Cane, J. H., Steffan-Dewenter, I., Cunningham, S. A., Kremen, C., & Tscharntke, T. (2006). Importance of pollinators in changing landscapes for world crops. Proceedings of the Royal Society B: Biological Sciences, 274(1608), 303–313. https://doi.org/10.1098/RSPB.2006.3721

3Hodgkiss, D., Brown, M. J. F., & Fountain, M. T. (2018). Syrphine hoverflies are effective pollinators of commercial strawberry. Journal of Pollination Ecology, 22(6), 55–66. https://doi.org/10.26786/1920-7603(2018)FIVE

Northern catalpa

On By veroiriartIn Love of FloraLeave a comment

One of the things I love the most about my Pittsburgh apartment building is that it’s situated right next to a huge northern catalpa (Catalpa speciosa) tree. And as I live on the top floor, the tree’s leaves come right up close to the windows of my sun room, where I do most of my remote graduate work. For this reason, I’ve gotten to spent a lot of time with the tree over the years and seemed to have bonded with it. Many times, the tree has been the only being that was there with me when I would stay up ‘til the wee hours of the morning, intensely typing on my laptop to meet some deadline. Sometimes, I would subject the tree to listening to my ramblings as I practiced giving a seminar presentation, and, bless its heart, the tree never judged me for it. But most of all, I appreciate those times when I’d take a break from my studies to gaze at the tree through the window, and its beauty would somehow relax me and give me strength to keep going.

The northern catalpa tree outside of my apartment building in Pittsburgh.

The northern catalpa tree through the sun room window.

Because of my attachment to the northern catalpa, I pay special attention to its status throughout the year and have gotten to know a decent amount about its biology. Now that it’s finally spring, for instance, I’m delighted that the tree has recently gotten back some of its most beautiful and characteristic traits, such as its large, heart-shaped, bright green leaves and long, bean-like seed pods that hang all around its branches. Because of these ornamental properties, the northern catalpa is widely planted across the United States, where it is native (USDA, NRCS. 2022). Fittingly, the name catalpa actually comes from a Cherokee word meaning ‘bean tree,’ and as a researcher of plants in the bean family (Fabaceae or Leguminosae), the seed pods were of course the first thing that attracted my interest. In reality, however, this tree is not a legume. It belongs to the Bignoniaceae family, along with many other ornate species of large trees and flowering plants you may see planted around cities and gardens such as the blue jacaranda and wax begonia. Later in the spring, I look forward to when the tree will start making flowers. These will be pollinated by bees during the day and moths at night, and then will fall like autumn leaves to sprinkle the path up to my apartment building with little white spots.

Other Bignoniaceae species. Left: Blue Jacaranda (Photo Credit: SOPA Images/LightRocket/ Getty Images). Right: Wax Begonia (Photo Credit: Shutterstock/Christopher_PB).
Northern catalpa flowers. Photo credit: David D. Taylor 2013.

Admittedly, it wasn’t until I started studying plant biology in college that I truly started to pay attention to the plants around me. This lack of attention to plants actually has a name, it’s called ‘plant awareness disparity’ (PAD) and it’s pervasive in modern life, despite the fact that plants account for 80% of the world’s total biomass and we depend on them for our essential human needs such as oxygen, food, and medicine (Bar-On et al. 2018, Brownlee et al., 2021; Parsley 2020). A big consequence of PAD is that plant conservation receives less attention and funding (Balding and Williams 2016). By taking some time to notice of the flora around us, however, we can combat PAD and support plant life. The website Plant Love Stories (www.plantlovestories.com) is full of inspiring, everyday stories of human-plant relationships (see this compilation piece I helped write that features many excellent plant love stories from University of Pittsburgh undergraduate students).

Although I know it can be easy to think of plants as the scenery to the movie that is your life, I am sure everyone could identify a plant that has made some meaningful connection with them as the northern catalpa has done for me. What plant has impacted you?

References

Balding, M., & Williams, K. J. H. (2016). Plant blindness and the implications for plant conservation. Conservation Biology, 30(6), 1192–1199. https://doi.org/10.1111/COBI.12738.

Bar-On, Y. M., Phillips, R., & Milo, R. (2018). The biomass distribution on Earth. Proceedings of the National Academy of Sciences of the United States of America, 115(25), 6506–6511. https://doi.org/10.1073/PNAS.1711842115/SUPPL_FILE/1711842115.SAPP.PDF.

Brownlee, K., Parsley, K., & Sabel, J. (2021). An Analysis of plant awareness disparity within introductory Biology textbook images. Journal of Biological Education,  https://doi.org/10.1080/00219266.2021.1920301.

Parsley, KM. (2020) Plant awareness disparity: A case for renaming plant blindness. Plants, People, Planet, 2, 598– 601. https://doi.org/10.1002/ppp3.10153

USDA, NRCS. 2022. The PLANTS Database (http://plants.usda.gov, 05/21/2022).

Polyploid Plants are Hopeful Monsters: Sci-Tech Days Outreach Event

On By veroiriartIn Science OutreachLeave a comment

Ever wonder why store-bought strawberries seem massive compared to the ones that you find in the wild? Or how some orchids sold at your local grocery store have flowers that stand out as giants among the rest?

Photo credit: Maine Agriculture in the Classroom

Well, in these cases, what causes some plants to achieve their monstrous sizes is polyploidy or whole genome duplication. You may remember that humans are diploid, meaning they have two sets of chromosomes, one from mom and one from dad (di = two, ploid = sets of chromosomes), and the vast majority of other animal species are diploid as well. Between 30 and 80% of all plant species, on the other hand, can have diploid or polyploid varieties1 with 3, 4, 5 etc. sets of chromosomes. For instance, one genetic variety of the Dancing Crane Cobra Lily (Arisaema heterophyllum)2 has as many as 14 sets of chromosomes, making it a decatettaraploid! Because polyploid cells hold more genetic material than diploid ones, they are often larger, leading to monster-sized organisms. Humans have taken advantage of these size differences for centuries3 to grow larger produce to eat (hence the store-bought strawberries which are actually octoploid) and flowers to ornament our homes (those large-flowered orchids are probably tetraploid4).

Diploid orchid (left), and tetraploid form (right).4

Although humans have long used polyploid plants to grow more attractive crops, there are still many unanswered questions about why plants naturally evolve to be polyploid in the first place. My colleagues in the Ashman lab, Dr. Thomas Anneberg and Dr. Nathalia Streher, are addressing these key questions with their research. Specifically, Thomas is using laboratory and greenhouse studies to understand ecological polyploid establishment in the face of competition, and Nathalia is using herbarium records to uncover how polyploidy has affected pollination over time. Recently, I had the opportunity to collaborate with Thomas and Nathalia for the “Hopeful Monsters: Studying Polyploidy” display at the Carnegie Museum of Science during the “Plants and Botany Sci-Tech Days” event. Although my research is unrelated to polyploidy, Thomas and Nathalia helped me learn about this exciting field of study and pass on knowledge to the museum visitors. Using techniques I shared on my previous blog post (Tabling at Science Engagement Week), we engaged with people who visited our table by using many interactive examples of polyploid plants. These examples helped to teach what polyploidy is and how ubiquitous it is in the plant world and everyday life. We called polyploid plants “hopeful monsters” because of their size, of course, and also because of the uncertainty surrounding whether they will evolve and/or persist in certain natural environments.

One of the greatest aspects of being part of a research lab is being able to interact with and learn from fascinating researchers like Thomas and Nathalia. I had a blast at SciTech days and felt that the experience helped me gain a new appreciation of the influence of polyploidy in biology, just as many of the school kids who visited our table did as well.

So the next time you gawk at a humongous fruit or flower, consider that polyploidy may have played a role in the making of that monster.

Hopeful monsters display at Sci-Tech days! Our table included many familiar polyploid plants that we frequently eat and interact with such as strawberries, bananas, peanuts, seedless watermelons, blackberries, yams, ferns, orchids, and hibiscus. From left to right: myself, Dr. Thomas Anneberg, Dr. Nathalia Streher, Jae Kerstetter, and Trapper Hobble. Kerstetter and Hobble are fellow University of Pittsburgh researchers from the Turcotte lab who also ran a display about their research.

Sources

1Otto, S. P., & Whitton, J. (2003). POLYPLOID INCIDENCE AND EVOLUTION. 34, 401-437. https://doi.org/10.1146/ANNUREV.GENET.34.1.401

2Hayase, Y., Himeno, R., Horii, Y., & Iwatsubo, Y. (2019). Tetradecaploid cytotype of Arisaema heterophyllum (Araceae), newly found in Japan. Journal of Japanese Botany, 94(1), 9–14.

3Grlesbach, R. J. (1985). Polyploidy in Phalaenopsis orchid improvement. The Journal of Heredity, 76, 74–75.

4Salman-Minkov, A., Sabath, N., & Mayrose, I. (2016). Whole-genome duplication as a key factor in crop domestication. Nature Plants 2016 2:8, 2(8), 1–4. https://doi.org/10.1038/nplants.2016.115

Tabling at Science Engagement Week

On By veroiriartIn Science Outreach, UncategorizedLeave a comment

When was the last time you stepped out of your comfort zone?

For me, the act of standing in front of an informational display table and conversing with strangers (‘tabling’) can be intimidating. However, I also realize how meaningful of an experience it can be when a scientist is able to use tabling to connect with people who otherwise would not appreciate the relevance of science in everyday life. Recently, I was fortunate to participate in a tabling workshop and run my own display for the first time. The display was centered around my research and occurred during ‘Science Engagement Week’ at the Phipps Conservatory and Botanical Gardens in Pittsburgh, PA. Although I was nervous about stepping out of the university bubble where I know my audience well (undergraduate students, professors, research technicians, etc.), this workshop taught me some new techniques that really helped me engage with the more general audience at Phipps. Here are the main takeaways I learned and how I used them at Science Engagement Week.

Tips for Successful Tabling:

  1. Have an opening hook: Much like the opening sentence of your college entrance essay, you want to grab people’s attention with something thought-provoking as soon as they step up to your table. What worked for me was asking people to examine the three clover plants I brought in and think about what could be causing the differences between them. The answer was genetics (the plants were from different genetic lines), but almost everyone gave the really excellent guess that varying environmental conditions (light, nutrients, precipitation, etc.) were causing the differences.
  2. Add interactive elements: Your audience will retain interest at your table for much longer if there are sensory objects present that they can put their hands on and interact with. In my case, the clover plants were also useful here because visitors liked to touch and turn over the leaves, smell the flowers, etc. They also seemed to like picking up and reading the laminated info-cards I scattered around, which also helped prompt questions about the background of my research.
  3. Ask open-ended questions: Conversations are a two-way street. As you’re tabling, provide many opportunities for visitors to share their thoughts and ideas so that you are not dominating the conversation. For example, I found it interesting to ask people about their professions and what activities they enjoyed doing in nature (of course, many responded that they enjoyed having house plants and gardening!). These open-ended questions helped me to not only connect with people more personally but also to find common ground for discussing the importance of doing ecological and environmental research.

By the end of the tabling session, I felt really good about the conversations I had throughout the afternoon. Folks seemed to show genuine interest in my work, and I enjoyed learning about their careers and hobbies too. Importantly, the practice of pulling off a tabling event solo gave me the confidence to tackle this challenge again in the future. In other words, the space outside of my comfort zone got a little bit smaller.