On July 19th, 2018 we learned about

Even with extra atmospheric carbon dioxide, plant-eating dinosaurs probably didn’t struggle with nutritional deficiencies

If a mouthful of meat has more calories than the same volume of veggies, how could the world’s biggest dinosaurs manage as herbivores? Between having relatively small mouths and a diet we presume to be based around green, leafy material, it’s hard to imagine how a 33-ton Apatosaurus could find time to do anything but eat in order to power its enormous body. To further complicate things, scientists have long believed that the higher concentration of carbon dioxide (CO2) in the Mesozoic atmosphere would have encouraged plant growth but left them with less nutritional value. Unless these animals had some amazing metabolic trick unheard of in any of their living bird and reptile relatives, the simplest explanation would be for some of these assumptions to be… wrong.

Approximating the Mesozoic atmosphere

As one of the key building blocks of plant life on Earth, CO2 availability does make a difference in how plants grow. Since it’s hard to pull nutritional data from fossilized wood or leaf impressions, scientists conducted an experiment, growing various plants in different atmospheric conditions. The plants were all picked as approximations of the species that lived millions of years ago, and included things like dawn redwoods, monkey puzzle conifers, ginkgo, ferns and horsetails. Naturally, these plants have likely changed to adapt to modern conditions on Earth in the last 65 – 250 million years, but they could hopefully offer a sense of how CO2 would affect their nutrient levels.

Growing a tree or fern in 400 to 2,000 parts per million concentrations of CO2 is only step one though. To figure out how much one of these high-carbon plants might benefit a hungry dinosaur, researchers had to next come up with a fake digestive tract, which they created by fermenting the plants in cattle rumen fluid for 72 hours. By capturing the various byproducts of this process, this technique is used to figure out how easily digestible food is for livestock, and thus could give us a sense of how easy or tough any particular plant was to extract nutrients from. Chewing and other processing strategies like gastroliths weren’t really included in the ‘simulation,’ although since different species of dinosaur ate differently, that seems like a fair omission.

Everything a growing dinosaur needs

In the end, researchers found that the extra CO2 didn’t reduce the nutritional value of these plants as much as had been previously assumed. A 33-ton sauropod was calculated to have only needed 242 pounds of monkey puzzle leaves grown in the CO2-rich Triassic air. That’s certainly a lot of food, but since it’s at the low-end for an African elephant’s daily intake, it would have certainly been possible. If that weren’t good news enough for large herbivores, researchers also found that some plants showed no loss of nutrition at all. A dinosaur eating horsetails grown at three-times modern CO2 levels would only need 112 pounds of food a day, assuming they really liked horsetails.

The overall takeaway is that herbivorous dinosaurs likely had a more nutritious salad bar than we’d ever thought. The gap between these nutrition values and earlier estimates suggest that ancient flora could have fed 20 percent more herbivores than anyone thought, possibly requiring reconsideration of dinosaur population density in general. As exciting as more giant sauropods and hadrosaurs may sound, not every animal would have benefited from these CO2-soaked leaves. Herbivorous insects rely a lot on nitrogen in the plants they eat, which was one of the few nutrients that was definitely reduced in the experimental plants. It’s too early to say at this point, but it’s possible that insect populations suffered in the way we had previously assumed dinosaurs did.

Source: The real palaeo diet: the nutritional value of dinosaur food by Susannah Lydon, The Guardian

On July 16th, 2018 we learned about

Mowing grass in varying degrees of moderation to promote plants, landscaping or pollinators

According to my kindergartner, the lawnmower was “amazing.” The shiny red tractor appeared to have an air-conditioned cab, three wheels and as my son put it, “two cutters” for the grass. It easily made short work of the city park we were visiting, presumably leading to the reopening of a field that had been temporarily closed to the public to allow the grass to recover from the beating it took during Fourth of July festivities. This raised a question for my son though— why was it bad for people to walk on the grass that this amazing machine was now chopping with it’s impressive “cutters?”

Lopping off portions of leaves

To make sense of how grass withstands regular trimmings, it helps to note how grass is structured. The flat ‘blades’ we like to feel under our bare feet are leaves the grow out of a smaller stem just above the plant’s roots. Like the leaves on a tree, losing some percentage of these leaves isn’t as dangerous as damage to the stem. Unlike leaves on tree, grasses have evolved to regrow the cropped portion of a leaf, ensuring that the effects of a modest mowing are only temporary. This likely evolved to help grasses survive visits from grazing herbivores, helping keep the grass and the nibbling animal happy as long as the plant’s stem isn’t trampled.

Mowing for more density

Humans are generally less concerned with grazing on our lawns these days, but there are still plenty of thoughts on how to properly manage grass growth cycles. If one’s goal is to maintain an even, densely-packed lawn, it’s recommended that you trim grass every week. This is to keep any single blades of grass from overshadowing their neighbors, leading to uneven growth overall. There’s also a risk of overcompensating after a lawn has grown taller than desired, as removing more than a third of the grasses’ height at once is more likely to stress the plants.

Pausing for more pollinators

On the other hand, most of us don’t play golf and don’t necessarily need the dense, homogeneous botanical carpet of a putting green. If that’s an option, allowing a lawn to have a bit more time between trims can promote the growth pollinator-friendly flowers like clover and dandelions. Even if you’re not interested in saving time, mower fuel or making tea from your yard’s yellow flowers, allowing some flowering plants to bloom in your lawn may make a big difference to a variety of bees. In a study by University of Massachusetts Amherst and the U.S. Forest Service, honeybees, bumblebees, carpenter bees, leafcutters, masons and sweat bees were all observed taking advantage of suburban lawns, but only if the lawns were mowed on a less aggressive schedule.

This doesn’t mean you need (or should) give up on mowing your lawn altogether. Some lawns in the study were only mowed on three-week cycles, but they didn’t seem to be any better than their two-week counterparts. The cause for this diminished return wasn’t immediately clear, but researchers suspect that three-week-old grass may be tall enough to hide some of these flowers, and thus didn’t provide much of a boost to pollinators.

Source: Why 'lazy' lawn mowers are heroes for bees by Russell McLendon, Mother Nature Network

On May 20th, 2018 we learned about

Corn seedlings use their roots to communicate about possible competition in shared soil

While plants can’t necessarily choose where every seed will sprout, they’re not completely passive about how the interact with their environment. Aside from reacting to possible predators, plants also need ways to deal with competition from other plants. In some species, this can mean pushing resources from growing roots to growing stems and leaves faster in order to stay out of a neighbor’s shadow. Of course, reacting to competition that’s already creating a problem may not be enough, which is likely the reason some plants seem to communicate their stress to their nearby relatives.

To investigate how these kinds of warning might work, scientists planted corn, then tricked it into worrying about competition. Every day, corn seedlings growing on their own had their leaves brushed to simulate contact with a neighbor’s leaves in the breeze. This was known to spur the seedlings to grow taller faster, which was observed as predicted. Once a seedling reacted to its faked competition in this way, the plant was uprooted so a new seedling could take its place in the same soil. Even though that second plant had never been brushed, it started growing taller as if it had experienced signs of competition. Since the two seedlings had never had direct contact with each other, and control plants that were simply transplanted didn’t react this way, researchers suspect that the seedlings are communicating through the soil.

Signals in the soil

While the exact chemical mechanisms remains to be isolated, the assumption is that this system would allow a plant to warn its kin of crowded conditions. Other seedlings nearby would then start growing taller faster, presumably beating out competition from other kinds of plants nearby. It might not be a huge benefit to the initial messenger that sounded the alarm, but it would help that species outpace the competition in the long run.

If humans can isolate this mechanism, we will be able to better understand plants’ health and possibly even coach them into more advantage growth patterns. From a passive standpoint, detecting this kind of chemical communication in soil may help us diagnose stressed ecosystems. More actively, it may help farmers better understand and control the growth rates of their crops, either encouraging more competitive growth rates, or maybe slowing things down to establish stronger root structures.

Source: Plants 'talk to' each other through their roots by Hannah Devlin, The Guardian

On May 3rd, 2018 we learned about

Understanding the mechanisms that let plants precisely sense which way is up

Without any eyes, ears or other familiar sensory organs, plants keep extremely close tabs on which way is up. Or, more accurately, they can sense exactly which way is down, generally so that they can grow in the opposite direction, as leaves and stalks aimed underground would otherwise be a waste of resources. Aside from the occasionally unreliable information we get from our eyes, humans sense up and down with tiny grains called otoliths in our inner ears. As it turns out, plants rely on a similar concept, just without needing an ear or brain to make it work.

Specialized cells called statocytes grow close to a plant’s vascular systems, both near stems and near roots. Inside those cells, organelles called statoliths behave a bit like analogs to our own otoliths. They can move freely within the cell, accumulating in the direction of the Earth’s gravitational pull. This then triggers changes in the plant’s allocation of growth hormones, shaping the direction of the plant’s overall growth.

Moving like a liquid

As similar as this solution is to what’s in our inner ears, plants may have an edge on the gravitropism, or gravity-sensing, abilities found in humans. The number of statoliths found in a single statocyst cell didn’t seem like they could provide the amazing sensitivity to “down” observed in plant growth. Most small particles tend to stick, clump and tumble in a group, which in this case would mean that plants would only get an accurate reading on gravity after the statoliths tumbled over, leaving the plant open to problems like vertigo. Strong wind that shook and regrouped the statoliths would leave plants in danger of constant disruption as well.

The answer seems to be that the statoliths aren’t as passive as we expected. They possess a mechanical ability that lets them avoid clumping altogether, constantly separating and resettling themselves into an optimal position. The result is that while a single statolith can be compared to a grain, a group of them in a statocyst operate more like a fluid, always filling the available space in the bottom of their container cell. This gives the plant an extremely precise and sensitive way to know the exact angle it’s growing at.

The best option isn’t always up

Even with this amazingly precise mechanism in their cells, plants sometime skip worrying about what’s up and what’s down. Light-sensing photochromes help a plant orient itself towards a light source, even when that means growing at an angle that “disagrees” with feedback from statoliths. As different photochromes picked up red or blue spectrum light, they can further inform a plant which direction to grow in, especially when that direction is more likely to help the plant photosynthesize its food.

Source: Why plants are so sensitive to gravity: The lowdown, Phys.org

On May 1st, 2018 we learned about

Some perennial plants can stay dormant for up to two decades

Spring is upon us, and all kinds of organisms are waking up from some form of dormancy or another. Frogs are thawing out their chilled bodies, bears are ending their hibernation, and perennial plants are regrowing lost leaves and stems. In most cases, this cycle is consistent and necessary, after all, a bear can’t store enough fat in its body to keep it alive for over a year of hibernation. However, scientists have found that at least 114 species of plant don’t need to follow this seasonal schedule. Instead of popping up each spring, their root stock can remain dormant underground for as long as 20 years without a problem.

At least the plants would hope there’s not a problem. Taking a break from normal growth cycles is risky- the plants can’t gather sunlight for photosynthesis, and they can’t create seeds or suckers to reproduce while dormant. Some of those concerns are mitigated by finding alternative sources of nutrition, such as gathering carbohydrates from fungi living in the soil, but the overall strategy is still a bit of a gamble. In going dormant for years at a time, a plant is essentially betting that its local environment will somehow be easier to live in years into the future, even though there’s no real way of knowing that.

Skipping threats, not seasons

Since all perennials go dormant during winter months when conditions are tough, researchers assumed that these multi-year periods of dormancy were just an extension of seasonal coping mechanisms. As such, they figured that they’d find more dormant plants in northern climates than at the equator, since seasonal conditions were more dramatic in those places. Instead, they found the opposite- mild winters and warmer climates actually had more plants sitting things out for years at a time, pointing a completely different set of influences.

In warmer, more equatorial regions, plants seemed to be going dormant to avoid less predictable threats than seasonal change. Disease, fires, predation from animals and competition with other plants were all tied to differing lengths of dormancy. In some cases, the threats were localized enough that a single species would stay dormant in one region longer than it would in another, again suggesting that plants were reacting to their local experiences over larger, systematic forces. From that context, the potential benefits of an extended dormancy start to look a bit clearer. Remaining dormant through dry, hot fire seasons may let a root stock regrow in an area suddenly soaked in the burnt but nutritious remains of what used to be competing species.

Widespread survival strategy

While some species of plants, like orchids, seem to have a bit of an affinity for this survival strategy, many species have evolved the ability for going dormant beyond a single winter. Since this trait is spread across many plant family trees, it’s thought that it must have evolved more than once, as a case of convergent evolution. Researchers also suspect that it’s an easy adaptation to acquire, possibly only requiring mutations in a few genes, although at this point the exact physiological and genetic mechanisms at play haven’t been directly identified.

Source: 'Rip Van Winkle' plants hide underground for up to 20 years by University of Sussex, EurekAlert!

On April 17th, 2018 we learned about

Describing, and disabling, a carnivorous plant’s version of consciousness

“Wait, how do plants know things? Do they know things? They can’t, right?”

My third-grader’s brow furrowed as she ran scenarios over in her head. Plants aren’t the same as animals. They don’t have muscles to move with. They don’t have eyes like we do, and no brain to do any thinking. Nonetheless, they are known to follow the Sun, open and close flowers, and even react to the sound of predators eating their neighbors’ leaves. How was any of this possible without the anatomical gear we depend on to do any of those jobs?

It’s a tough question, and we don’t know all those answers yet. The sound sensory in particular is quite odd, but fortunately, some very reactive plants have helped botanists figure out how a plant can sense and respond to stimuli without nerve cells and a brain to do so. Because carnivorous plants like the Venus flytrap (Dionaea muscipula) and sundew plants (Drosera) have to actively trap their prey, they need to operate in a time-frame that matches the critters they want to catch. To do that, the plants are relying on so-called trigger hairs that essentially give the plant a way to “sense” when something has touched it.

As the titular fly lands on the attractively-scented “lobe” at the end of a leaf, it’s likely to bump into one or more trigger hairs. Unlike your nerve cells, those hairs don’t report back to any brain to trigger further activity. Instead, they create an action potential, which is an electrical charge that builds up in the trigger cell, eventually reaching a threshold where it gets discharged to the next cell, and the next, and the next. Eventually, this signal reaches the plant’s version of a muscle cell, which either expands or contracts to change the water pressure along the joint of the mouth-shaped lobe, causing it to close shut on the bug. With further stimulation of those trigger hairs, the flytrap will start to excrete digestive enzymes to it can actually eat its prey.

Turning off the trigger hairs

Even though trigger hairs aren’t exact matches for animal nerve cells, they’re close enough that they can be used to study the effects of the general anesthetics we use on animals. Even though those drugs are used every day to numb and temporarily paralyze people in surgery, we don’t know exactly how they do it. By using them on reactive plants like Venus flytraps and the “shy plant” Mimosa pudica, researchers are getting closer to understanding the exact cellular mechanisms that make modern surgery possible.

The answer seems to go back to the idea of action potentials, and how they get started in the first place. In both the plants trigger cells and animal nerves, a charge is built up on the outside of the cell membrane or wall. In the membrane are openings called ion channels that open and close when specific molecules are present to unlock them, a bit like a key opening a gate. Charged molecules, ions, can then move into the cell, helping it accumulate a larger charge, until eventually it triggers the release of an electrical charge to kick off another cell.

Paralyzing the plants

When carnivorous plants were subjected to anesthetics like diethyl ether, their trigger cells became unresponsive. The shy plant didn’t curl its leaves. Flytraps didn’t close after being poked. More importantly, no charge was detected at the plants’ trigger cells, indicating that the ion channels weren’t opening, heading off any action potential before it started. A second test with the roots of a mustard plant, Arabidopsis thaliana, found that the lipids, or fat proteins, in the cell membrane were being disrupted, helping researchers narrow their focus even further.

This wasn’t done to numb Venus flytraps, of course. They seem to be quite good at regulating their own activity already; they only close if multiple hairs have been touched, don’t usually close down on their pollinators, and reserve digestive enzymes for when they really have lunch in their clutches. Instead, this work may help us understand and then design better anesthetics for humans and other animals, taking some of the trial and error out of how we temporarily stop each other from sensing the world around us.

Source: We can make plants pass out—with the same drugs that mysteriously knock us out by Beth Mole, Ars Technica

On April 15th, 2018 we learned about

Beyond bugs, mammals, birds and reptiles play big roles in the pollination of flowering plants

On paper, the tongue of a Pallas’ long-tongued bat (Glossophaga soricina) may sound a bit like something from a horror movie. The South American bat’s tongue is made of spongy, erectile tissue, allowing it to increase its length by 50 percent when engorged with blood. It’s covered in an array of tiny, densely-packed hairs, which then stand perpendicular to the tongue when fully extended, allowing it to better capture the fluids the bat devours to stay alive. In practice though, none of this seems very grotesque, because G. soricina only uses its tongue to lap up nectar out of flowers, placing this bat in a niche closer to a honeybee than a vampiric parasite.

Scientists studying pollinators have found that the importance of vertebrate pollinators like G. soricina may be widely underappreciated. For all the attention played to pollinating bees and butterflies, a large number of plant species largely depend on bigger critters like bats, mice and even lemurs to fertilize their flowers. These aren’t strictly fringe cases either, as some flowers have evolved to be highly specialized, and thus dependent on just the right species of mammal or bird to be able to reproduce.

Nectar-eating bats and birds

Among mammals, bats are the most common pollinators, sometimes accounting for 83 percent of fruit production in a geographic region. They’re known to pollinate close to 530 species of plants around the world, often in relatively exclusive arrangements. For example, the blue agave cactus (Agave tequilana) which is used to make tequila, only open their flowers at night in order to attract greater (Leptonycteris nivalis) and lesser (Leptonycteris yerbabuenae) long-nosed bats. These bats don’t have hairy tongues, but the hair on their bodies collect and spread pollen just like the fuzz on a bumble bee.

As the specialized beak and tongue of a hummingbird indicates, many species of our feathered friends also act as important pollinators. Beyond hummingbirds, 920 species of bird are known to spread pollen between flowers, and are estimated to account for five percent of flower fertilization where they live. In more isolated environments, like islands, that number goes up, with birds being responsible for at least ten percent of flower pollination.

No need to fly to flowers

The success of pollinating bees, bats and birds may suggest that flight is somehow necessary to pollinate a flower, but that’s not the case. Any animal that wants to sip nectar without destroying the flower that produced it can potentially act as a pollinator, which has lead to at least 85 plant species around the world that get regular visits from non-winged mammals. Mice, squirrels, possums and lemurs may all stick their noses into flowers enough to transport pollen. Even without fur, bluetail day geckos (Phelsuma cepediana) can act as pollinators, carrying sticky pollen on the tips of their noses.

As humans become more appreciative of how insect pollinators help keep ecosystems alive, this research shows that we need to also consider the bigger-bodied pollinators as well. As policies and even substitutes are being developed to help protect creatures we associate with plants humans grow on farms, we need to make sure the wider range of pollinators around the world are protected as well. After all, some of these pollinators have become very adept at their sticky, hairy line of work, and won’t be easily replaced.

Source: Lizards, mice, bats and other vertebrates are important pollinators too by Ecological Society of America, Phys.org

On January 21st, 2018 we learned about

Chile peppers produce more spicy capsaicin when they’re fighting more fungi

Bugs make food taste better, at least in the long run.

From the crisp snap of wasabi to the soothing bitterness of coffee, many of our favorite flavors have been created in response to some kind of predatory insect. Bitterness is generally a sign of toxicity, which in foods like broccoli or coffee beans, evolved to deter bug that would otherwise destroy a plant’s chances of reproduction, usually by eating fruit without dispersing its seeds. Pepper plants take this mouth-watering defense up a notch, trading bitterness for spicy capsaicinoids, like the capsaicin found in a jalapeno pepper. It’s less subtle than broccoli’s bitterness, but it also has to pull double duty, repelling both insects and fungi that would harm the pepper.

More parasites means mas picante

There are many of pathogens that can harm a plant, but a pepper’s capsaicinoids probably evolved to help fight fungi that target their seeds. Ideally, a pepper, as the seed-carrying fruit of the plant, would be carried by an animal to a new location where those seeds could be dispersed. Fungi then pose a specific threat because they consume the seeds themselves, wasting all the resources the plant put into growing the seeds and fruit. Capsaicinoids help fight the fungi as well as the insects that help the fungi gain access to seeds in the first place.

Researchers studying capsaicinoid production in various peppers found that the plant’s location played a big role in how spicy they’d turn out to be. Cooler areas produced milder peppers, while hotter locales produced spicier fruit. Focusing in on the Capsicum chacoense pepper from Bolivia, researchers found that hotter peppers were first attacked by insects, and that the scars left in the fruit by those bugs provided entry points for fungal parasites. So the plants that were at more risk of fungal infection then produced more capsaicin to act as a bigger dose of fungal protection. This is likely why the seeds of many chiles pack a much bigger punch than the flesh of the fruit itself- that delicious burn is concentrated where it’s needed most.

Bland for the birds

So if fiery peppers evolved to be avoided by insects and fungi, what creature provided the proper seed dispersal for these plants in the first place? While humans have come to enjoy the burn of a good chile pepper, most mammals aren’t so keen on a spicy dinner. Birds, on the other hand, don’t have capsaicinoid receptors in their mouths, leaving them to enjoy the vitamins, sugar and fiber found in a pepper without any sense of the burning we get to experience. The birds are probably happy with this arrangement, but it’s hard not to feel that they’re missing out on the pleasurable pain a good pepper can really add to your meal.

Source: There's a fungus among us and it's making peppers spicy by Jennifer Tsang, The Microbial Menagerie

On January 3rd, 2018 we learned about

The word pineapple made more sense when everything was apples

Pineapples obviously don’t resemble apples, but they used to. This isn’t because pineapples used to have thin peals and white flesh before humans started cultivating them, but because people’s concept of what an apple is has changed since the fruit was first identified by European explorers. For hundreds of years, the word apple could be used for just about any unknown fruit, even if they were in no way related to plants in the Malus genus. Following this logic, peaches were first known as “Persian apples,” and bananas were once “finger apples.” This then leaves us with the “pine” in name pineapple, which still doesn’t make much sense.

Since pineapples don’t even grow on trees, it’s clear that nobody thought these tropical fruits were somehow growing on spruce or redwoods. What they did think is that pineapples looked a lot like pine cones, which, in 16th century, were still called pine apples themselves, since they produced seeds while growing in a tree. So from a 16th century perspective, pineapples do look like their namesake, at least before we changed the name of the plants that were being referred to. In the case of pine cones, the use of the word cone was borrowed from the Greek kōnos, and eventually passed from more academic botanical discussions to common English by the 18th century.

When is an apple not a fruit?

Apple is obviously no longer a generic term, now used exclusively for expensive computer hardware or the fruit of the Malus pumila tree. The word fruit itself is now our best generic term for tree-bound produce, although it too has a narrower definition than it used to. In the late 12th century, fruit could be any “useful” portion of a plant, with etymological roots in words for enjoyment and satisfaction. At some point, it could even be used for any product grown from soil, from nuts to veggies, and so the idea of a reward being the “fruit of one’s labor” barely qualifies as a metaphor.

Today, fruit covers a lot of the ground that the word apple used to, but it has also gained a strict, botanical definition. The funny thing is that since fruits are “seed-bearing structures in angiosperms formed from the ovary after flowering,” pine cones, as the original pineapples, can’t really be considered fruit at all. With pineapple’s linguistic connections being erased bit by bit, maybe it’s time English speakers simply joined the rest of the world and picked up the word Ananas. It wouldn’t be any more confusing than what we’re saying now.

Source: A Pineapple Is An Apple (Kind Of), Merriam-Webster Word History

On January 1st, 2018 we learned about

Scientists find the molecular mechanisms that help flowers survive their own deadly fragrances

Smelling nice is a luxury for humans. Skipping deodorant isn’t really going to hurt us, although it may bother whomever we stand next to on the bus. For flowering plants, emitting a pleasant, or maybe just strong, smell isn’t a choice. Beyond helping to attract pollinators and signal growth cycles, researchers have learned that flowers must get their attractive odors into the air, because holding them inside would be fatal. Now a series of experiments has figured out exactly how flowers keep themselves safe from their own delightful fragrances.

The gases that we usually refer to as a flower’s fragrance are technically known as “volatile organic compounds,” or simply volatiles. While volatiles tickle our smell receptors when they enter our nose, they’re toxic to the plant cells that produce them. The realization of this critical fact forced scientists to rethink their original model of how flowers release volatiles so animals can smell them, which stated that the fragrant molecules passively diffused through cell walls into the atmosphere. However, that process would actually be much to slow for the health of the plant, prompting further investigation into how plant cells send their scents into the air.

Isolating petunias’ volatile pump

The first part of the study looked at petunias, as they release very few volatiles as buds, but really pour them out when the flowers have bloomed. The contrast between these two phases allowed researchers to look for genes that were more or less active at either time, revealing which genes and therefore molecular mechanisms were being cranked up to push more volatiles out of the flower’s cells. The answer was a type of ATP-binding cassette transporter, which flowers use to not only move volatiles, but other compounds like a leaf’s wax coating as well. The volatiles were actually moved out of the cell thanks to combinations of hydrophilic, or water-attracting, and hydrophobic, or water-repelling molecules. The volatiles themselves are also hydrophobic, and so the right combination of similar and contrasting molecules could effectively shove the volatiles out of the cell after they were produced.

To test this hypothesis, researchers manipulated the transporter genes in petunias and other plants. In flowers that presumably relied on these genes to eject volatiles, the genes were suppressed, leading to less fragrant blooms and eventually more dead cells thanks to a build-up of volatiles. On the flip side, the transporter genes were added to non-flowering tobacco plants, then dosed those plants with potentially dangerous volatiles. As expected, tobacco that had the volatile transporter genes could keep its cells alive by pumping out volatiles. Normal tobacco plants that lacked this extra mechanism couldn’t cope, and died like the genetically modified petunias mentioned earlier. Thanks to these experiments, scientists now know exactly how flowers survive their own scents, and may be able to further control volatile output in the future.

Source: Stopping to smell the roses? You’re inhaling flower farts by Abrahim El Gamal, Massive Science