Plants – TylerJFord.com

July 31, 2019

Details beneath the surface: A tree’s encounter with seasons

This post was contributed by guest blogger Jennifer Tsang, the science communications and marketing coordinator at Addgene and a freelance science writer.

A tree has a lot more going on than what meets the eye. As its leaves grow and fall, its metabolism changes, and the tree undergoes an internal overhaul. Somehow trees know exactly when these things need to happen and, each year, they happen at approximately the same time. This is a marvel of synchronization – both at the level of the trees themselves and across an individual tree’s cells. How do trees achieve this synchronization? And what are trees doing in the “in between” times of summer and winter, times when it’s hard to see much surface-level change?

Answering these questions may help us understand how trees and other plants will react to the seasons in a changing climate. Maybe we’ll even be able to work with our arboreal partners to adapt to a warming world.

Spring forward

Let’s begin with spring, the season when it seems that all life wakes up and makes an appearance: birds, flowers, even humans. For trees, spring is the time to start sprouting leaves. But how do trees know when to unfurl their foliage? For many trees, this decision depends on both day length and temperature. Trees can “see” day length using photoreceptors, sensors in their buds and on their trunks. Daylight of a certain duration signals the trees to begin budding.

Once leaves have sprouted, trees are prepared to soak up the summer sun. Leaves are chock full of chlorophyll, a green pigment that, along with sunlight, helps trees produce the sugars they need to grow. Trees spend spring and parts of summer using their leaves to generate sugars. These sugars are stored and used for energy. Before trees hunker down for winter, they also produce buds in preparation for the next year. They do so even before their current leaves fall.

Summer slowdown

As the end of summer approaches, some trees such as wild cherries slow down photosynthesis even though the sunny days continue Remember, trees produce sugars through photosynthesis. They need room to store all that sugar but have limited storage space. Thus, they slow down photosynthesis as storage space fills up. Larger trees, however, have more room for storage and will carry out photosynthesis right up to the first frost. Even in the summer, the trees know: Winter is coming.

Fall for falling leaves

Autumn’s signature explosion of color is a result of winter preparation and resource conservation. During this time, trees break down chlorophyll and store its components until spring when they can send them back out to new leaves. Without the green pigments of chlorophyll that dominate leaves in summertime, the reds, oranges, and yellows start to come out. These colors come from other pigments such as carotenes and xanthophylls. (Fun fact: carotenes and xanthophylls make carrots orange).

Cross-section of a leaf changing colors. Pigments such as chlorophyll, carotenes, and anthocyanins give us wonderful fall colors. Figure source: wikipedia.

Just as leaf growth depends on temperature and day length, trees look to these signals to decide when to shed their leaves. Contrary to what we may think, dropping leaves is actually an active process: trees grow layers of cells that sever leaves from their branches. Thus, the leaves fall with even a light breeze.

Winter hibernation

Trees shutdown many of their biological processes during winter. As part of the shutdown, trees dehydrate themselves. Freezing water expands and if a tree is too wet in the winter, it can burst. As such, some trees even begin cutting back water intake as early as July. Cells that make up leaves also hold water, so they would rupture in the winters if they didn’t fall off. Such ruptured leaves would be useless for photosynthesis.

There’s actually another important reason why leaves fall: snow is heavy. If it accumulates on leaves, it could cause trees to bend over and break. Without leaves, trees are also less susceptible to high winds during storms.

Mixed signals: changing climate against steady daylight patterns

We’ve seen that day length and temperature are important cues throughout the year so how do rising temperatures affect the yearly cycles of trees? While temperature is affected by climate change, day length is not. Importantly, not all trees depend on day length and temperature in the same way. Some trees rely on temperature more than day length to tell time. Warming temperatures can change the length of the growing season and either delay or accelerate growth cessation in the fall.

Changes in temperature can also mean trees begin budding leaves at the wrong times. They might waste energy growing new leaves before it’s consistently warm and sunny enough for them to photosynthesize effectively. The end result: a mixed bag. Some trees might thrive in warmer temperatures while others will be woefully unprepared.

Thus the changing climate will likely shift the distribution and diversity of tree species in nature. It’s unclear what the ultimate effects of these changes will be, but other species are sure to notice the changes in the trees. After all, we depend on trees for food, building supplies, medicines, and much more. Let hope we can find new ways to protect our arboreal friends and their beautifully complex lives!

Jennifer Tsang is the science communications and marketing coordinator at Addgene and a freelance science writer. She has completed a Ph.D. in microbiology studying bacterial motility and studied antimicrobial resistance as a postdoctoral fellow. She writes for her own microbiology blog called The Microbial Menagerie. You can follow her on Twitter (@jw_tsang).

April 8, 2019April 8, 2019

Delving into SciComm by Tyler’s Instagram stories: Biosensors, Komodo dragons, lab meat, and more!

Stories from the SciComm by Tyler Instagram account

I often come across interesting biology facts. I spam these facts in polite conversation, but I’ve also decided to share them in a more productive way on Instagram. On the SciComm By Tyler instagram account, I’ll post detailed drawings coupled to nuggets of biological intrigue. Some of these will come from blog posts. Through the stories feature, I’ll share more bite-sized biological morsels. I’ll couple the stories with goofy doodles (sometimes I’ll recycle these from my gallery :P). At the end of each week, I plan on delving into the stories in a little more detail through a blog post.

Below, I expand on my first week of stories. Enjoy!

Please follow me on Instagram if you like what you see :D.

Biosensors are biological machines that detect objects and events

I wrote a bit about biosensors in an older blog post. As a refresher, biosensors are biological machines that detect specific objects and events. They have many research uses. They can detect chemicals, they can detect organisms, and some can even count how many times cells divide.

I first became enamored with biosensors during my PhD work. For part of my work, I tried to get bacteria to turn sugar into gasoline. To see if my bacteria were accomplishing this goal, I designed a biosensor. This biosensor made the bacteria turn red if they produced gasoline-like chemicals. Indeed, the more gasoline-like chemicals they produced, the more red they’d become. Unfortunately, my biosensor wasn’t particularly sensitive so I abandoned it (such is the nature of many experimental research projects!).

Others have created more useful sensors. The doodle above illustrates a biosensor that detects DNA. Such biosensors bind to specific DNA sequences and glow. They help scientists understand how DNA sequences interact with other things in cells. Using many different biosensors, scientists learn how cells function. Scientists can then use their knowledge to create therapeutics or even design cells that do cool things like attack cancer cells!

Komodo dragons use venom to kill prey

I think Komodo dragons are super cool. Even if they don’t breathe fire, they’re still basically dragons. Long ago, I was told that Komodo dragons don’t directly kill their prey. Supposedly, they instead transferred bacteria to their pray through biting. The resulting infections then killed their prey over time. Recently, I learned that RESEARCHERS DO NOT BELIEVE THIS ANYMORE. Indeed, when I was at the San Francisco Zoo a few days ago, I read that Komodo dragon bites inject venom into their prey. This venom kills prey through a mixture of physiological effects. For instance, the venom can lower blood pressure and prevent clotting. It’s not fire, but it’s pretty brutal!

Some frogs survive being frozen

Okay, I’m a molecular and cell biologist at heart, but I love me a good animal fact! I picked this one up while watching one of the many BBC nature documentaries on Netflix. I don’t have much more information than what’s in the image. I just think it’s really cool! Hopefully, I’ll dive into this in a dedicated post at some point.

Some bacteria inject DNA into plants

Doodle of an agrobacterium injecting DNA into a plant

Bacteria do soooooo much more than make us sick. There are many bacteria that do good things. We’ve even figured out how to turn some dangerous bacteria into useful tools. For example, there are bacteria that use teeny tiny needles to inject their DNA into plant cells. These bacteria naturally cause plant diseases. However, scientists have figured out how to use these bacteria to deliver useful DNA sequences to plants. They can even use these bacteria to make crops resistant to pests! Learn a little more about plant biotech in this post.

Complex meats are hard to make in the lab!

Many companies are working to grow meat and meat-like products in the lab. They hope to produce these “meats” more sustainably than livestock. They are having a lot of success growing meats like chicken nuggets or ground beef. However, it will be some time before we have more complicated meats like steaks or pork chops. The complex structures of these meats are difficult to create in the lab.

That’s all for this week. Please follow me on Instagram to check out my stories in real time. Cheers!

February 5, 2019March 18, 2019

The “properly” anthropomorphized flower

Very often, I anthropomorphize cells and other biological objects in my drawings. I’ve turned bacteria into pirates, phages into bandits, and muscle cells into builders. It is my hope that presenting biological concepts in this way helps you understand and remember them better or helps you think about them in a new way. In this post, I take anthropomorphism to somewhat of an extreme with what I’m calling a “properly” anthropomorphized flower. Reading this post, I hope that you’ll develop a deeper appreciation for what a flower really is as we approach Valentine’s day.

The problem with the smiling flower

Although you can find many cute flower cartoons depicting smiling faces surrounded by petals, it’s a bit odd to compare flowers to faces. You see, while plants can certainly sense many of the things we sense with our eyes, noses, mouths, and ears, they don’t have faces per se. For example, the mouths should be distributed more to the leaves and roots. The leaves “eat” sunlight and carbon dioxide while the roots “eat” other nutrients found in soil and fertilizer (e.g. nitrogen and phosphorous).

When thinking about its biological function, the flower itself is possibly the most lewd thing one could represent as a face. The flower is censored in my drawing because, in reality, flowers house the reproductive organs of many plants. Insofar as a plant’s reproductive organs can be compared to those of humans, single flowers often contain both male and female parts. In fact some flowers can fertilize themselves. In the floral fertilization process, pollen constitutes floral sperm while eggs can be found within the depths of the flower. I find this all very cool but, were I to draw these parts only my anthropomorphized flower, I might turn away some of my audience.

If my drawing didn’t focus too much on the flower’s innards and instead focused on its petals, the censor bar might might not be required after all. This is because you might think of a flower’s petals as gorgeous clothes. These beautiful garments help attract pollinators like bees, much like we use clothes, jewelry, and hairstyles to attract mates when going out on the town (hence the dancing flower below).

A flower that's ready to dance — This flower is ready for a night on the town.

In any case, I hope you’ve found my “properly” anthropomorphized flower enjoyable. With a little more plant know-how, maybe you’ll further appreciate the complexity and life hiding behind the petals you see in your next bouquet!

October 31, 2018October 31, 2018

3 Things I Learned Recently about Plant Biotech

Plants! We’ve been experimenting with them through farming and breeding for ages and we’ve had many successes (just look how corn has changed from its ancestral form for a great example). Nonetheless, more can be done to lower costs, increase variety, and improve nutrition (among other things). Here are just a few things I’ve learned about recently – engineering more stable animal feed, changing flower color, and making apples that don’t brown.

1. Making More Stable Animal Feed

Cheese burgers are delicious. However, to keep making cheese burgers, we need to keep making cows. A lot of money and resources go into making the tasty animals we eat (a good reason to be vegetarian at least some of the time) and farmers are always looking for ways to decrease costs.

Luckily, plant researchers have taken note. One way researchers are trying to lower farming costs is by making plants used for animal feed more stable. The plants we feed to animals often need to be stored prior to feeding and their nutritional components can degrade during storage. Scientists at the USDA are specifically altering alfalfa (apparently a component of feed) so that it produces chemicals that keep its proteins from degrading. This stronger alfalfa could some day lead to healthier, less expensive animal feed.

2. Changing Flower Color

Have you ever wanted a particular type of flower to come in a different color? Plant breeders have been changing flower colors for years by crossing different varieties together. The process of altering the genes present in a particular plant (really what you’re doing in plant breeding) may be more straightforward and controllable if performed using genetic engineering techniques.

Toward this end, researchers recently used the genetic engineering tool, CRISPR, to change the Japanese Morning Glory from violet to white. This specific color change isn’t groundbreaking as there were already white Japanese Morning Glories, but it shows that CRISPR can be used to quickly get a desired color if we know enough about the underlying biology.

The company Revolution Bioengineering is doing something perhaps a little more exciting – they’re making flowers that change color overtime. I’m intrigued to see how things turn out!

3. Marking Non-browning Apples (Arctic Apples)

I often find myself cringing before taking a bite out of a brown apple slice that’s been out for too long so I was excited to discover that the company Okanagan Specialty Fruits makes genetically modified, non-browning apples (see description on their blog). They call them “Arctic Apples.”

Apparently these apples have been in production for a while but they’ve only been sold in the U.S. since early 2017. Full disclosure, I haven’t eaten them yet and can’t vouch for their taste, but I’d love to try them out.

There’s all sorts of other stuff going on in the world of plant biology and I’m hoping to touch on some fancy things like plant metabolic modeling and engineering carbon fixation in later posts. Stay tuned!