Category Archives: GMO

Independence Day: Red, White and Blue

In celebration of July 4th, this typically green blog is going red, white and blue.

Red

There are lots of connections between plants and the color red. Roses are red. Plants emit a faint red fluorescent glow, as I wrote about in my previous post. But it isn’t all about plants; there are other photosynthesizers, like algae. While green may dominate your perception of algae, there is an entire group of red algae, the Rhodophyta, that exist below the surface of marine environments. Like plants and green algae, they are eukaryotes, but they have many photosynthetic characteristics that are closer to the prokaryotic cyanobacteria. Most notably, they contain the phycobilisome antenna structures to funnel light into their photosynthetic machinery. Since the red algae live in the ocean below other photosynthetic organisms, they take advantage of the higher-energy blue light that penetrates deeper into the water. To do this, they make the phycoerythrin pigment which appears red. This may sound exotic, but you may be more familiar with red algae than you think. The agar and agarose used in microbiology labs is derived from species of red algae as well as the nori used to roll your sushi.

Red Algae Chondrus Cripsus via Wikipedia

White

The ‘color’ white in plants is an interesting case. It means that no pigments are present, and all visible light is being reflected from the plant tissue. Very little, if any, light is being absorbed. Since their lives depend on converting sunlight into chemical energy, reflecting all of it away from themselves represents a risk by the plant. However, it is a calculated one that pays off. The white tissue of flowers depends on the other green parts of the plant to supply it with sugar and other energy molecules for biochemical support, but it creates a contrast from the rest of the plant. In this way, the plants have made it easier for pollinators to home in on flower tissue with its nectar and pollen. It creates the most basic win-win situation for plants and pollinators- no extra biochemical pathways required. Of course, some ‘plants’ take white too far and lose the ability to be photosynthetic as in the case of the ghost plant.

Pentas lanceolata via Wikipedia

Blue

True blue can also be difficult to come by in the plant world. Because blue light resides on the high-energy side of the light spectrum, it is in the best interest of the plants to absorb that energy to drive photosynthesis. Indeed, the antenna pigments of photosynthetic organisms are very good at absorbing blue and red light. However, some plants can make a special class of anthocyanidin that reflect blue light. Pigments like delphinidin give larkspurs, violas and grapes their distinctive bluish hues. Alas, not all plants have the biochemical pathways to create blue flowers, but the demand for blue blooms in the horticultural sector doesn’t let nature get in its way. Plant scientists can use biotechnology to insert the genes necessary to produce the blue pigment. While true blue roses haven’t quite come to fruition, blue varieties of carnations and chrysanthemums have been engineered.

Delphinium x Belladona Bellamosa via Wikipedia

These examples show that the photosynthetic world can be patriotic as well. Colors, like red, can come from common places and overlooked depths, while white can be a beneficial sacrifice. Blue can be true or migrate in from exotic sources.

 

Johnna

References and Links:

http://en.wikipedia.org/wiki/Red_algae

http://www.ucmp.berkeley.edu/protista/rhodophyta.html

http://botany.si.edu/projects/algae/classification/RHODOPHYTA.htm

http://marinelife.about.com/od/plants/p/redalgae.htm

http://www.life.umd.edu/labs/delwiche/PSlife/lectures/Rhodophyta.html

http://en.wikipedia.org/wiki/Delphinidin

http://en.wikipedia.org/wiki/Blue_rose

http://www.ncbi.nlm.nih.gov/pubmed/23926063

http://www.gmo-compass.org/eng/news/stories/350.genetic_engineering_cut_flowers.html

http://www.nwrage.org/content/florigene-develops-worlds-first-biotechnology-driven-blue-roses

April Berry Go Round: Plant Colors

When your life depends on light, as it does for plants and other photosynthetic organisms, color is important. Even the most flamboyant displays are functional not frivolous. Beyond being a consequence of the biophysics of photosynthesis, these exhibitions are used to attract pollinators, to send warnings to would-be herbivores, and to adapt to their surroundings. Of course, humans find these colors fascinating for reasons unrelated to their purposes for the plants. As a result, these beautiful botanicals have become entwined with human culture as well- in our gardens, in our kitchens, and in our artistic expressions. This edition (#69) of the Berry Go Round blog carnival explores the diverse topic of plants’ use of color.

Before we delve into the details of how plants use their colors or the extreme colors plants employ, start with this post from the As many exceptions as rules blog, which describes the extensive biochemical repertoire of plant pigments. Now let’s take a journey across the wavelengths of the spectrum of visible light. As you will see, plants don’t let any wavelengths go to waste. There is a purpose for every color and then some.

Spectrum of visible light via Wikipedia Original source: hi:Image:Srgbspectrum.png

When it comes to the color red, this vibrant color serves as an attractant that is perfectly adapted to the visual systems of their bird pollinators. The color red is also a strong attractant for humans because plants like Rubia tinctorium became so popular at one point as to be synonymous with empires.

Colors can be simultaneously beautiful and delicious as described in this post by Sarah Shailes. If you’ve ever wondered why saffron is so expensive, you should definitely click the link. A common flash of yellow in Louisiana these days is the yellow iris, which is the subject of this post by Dave Spier at the Northeast Naturalist blog.

Green is so ubiquitous among plants that it is often taken for granted. Yet plants do not take it so lightly, as explored in this post Beyond Green at the Postdoc Street blog. This post on the Plants And Rocks blog also describes how green bark can help give aspen trees a head start on photosynthesis before their leaves develop.

In the literary world, violets may be blue, but other botanicals come much closer to true blue in real life. One striking example that you may not be familiar with are the seeds of the Malagasy traveller’s tree (Ravenala madagascariensis) described in this post from Kew Millennium Seed Bank blog. When it comes to indigo, the plant and the color are one in the same. Find out more about the plant behind this pigment in this post by Sushmitha on a Blog of Scientific Nature.

There’s a new kid on the block when it comes to purple plants- the tomato. There are some heirloom varieties of purple tomatoes, but recently genetic engineering has been used to increase the amount of anthocyanins (antioxidant pigments) in tomatoes. Read more about them (and other genetically engineered plants) in this post by Izzy Webb on the John Innes SVC blog. Of course, other naturally-occurring pigments are found in our favorite edible plants. Check out the chemistry in these posts on Beetroot and Grapefruit from the Compound Interest blog.

Plants also display other colors beyond the typical rainbow of the visible spectrum. In fact, one species of tree, the rainbow eucalyptus, lives up to its name in a display of color more akin to the neon colors of an ‘80s music video than nature.

A grove of Rainbow Eucalyptus Eucalyptus deglupta trees, planted along the hana highway, Hawaii. Credit: Amelia via Wikipedia http://www.flickr.com/photos/amelia525/303049143/

Other plants are studies in monochrome. Ornamentals like the black pearl peppers described in this post by Mark Dwyer at the blog of Rotary Botanical Gardens in Wisconsin are entirely ink black– leaves and fruit. Emma Cooper offers you a steamy list of fifty shades of grey in the garden. Don’t worry, these are suitable for public display. Rebecca Deatsman describes a plant on the other end of the spectrum on her blog Rebecca in the Woods- the completely white Indian Pipe. It may look like a fungus, but it’s really a plant despite the fact that is eschews a photosynthetic lifestyle. I’ve mentioned before on this blog that it lacks all pigments required for photosynthesis and therefore lives a shameful (for a plant) heterotrophic existence.

Black Pearl Pepper by Mark Dwyer, Rotary Botanical Garden reused with permission

Montropa Uniflora stem detail. Matthew S. Staben via Wikipedia

Over at The Botanist in the Kitchen blog, Jeanne L. D. Osnas serves up a colorful nasturtium salad with a helping of explanations on the patterns plants use as ‘nectar guides’ to direct their pollinators to their sweet spots. There are also some great examples of how plants use colors that human eyes can’t see. When the pollinators are insects with the ability to see ultraviolet colors, some plants color their flowers with pigments that reflect UV rays. Take some time to chew on the fact that the flowers that bees see have patterns on them that you cannot see.

Mimulus flower photographed in visible light (left) and ultraviolet light (right) showing a nectar guide visible to bees but not to humans. By Plant Surfer via Wikipedia

Simon Norton Museum via Wikipedia

Think it’s silly that plant patterns would create such a frenzy in a species from another kingdom? Before you start to feel too superior, consider the tulip. Fortunes were traded over the newest colors and patterns of tulips in the late 17th century in the Netherlands. Shown at the right is a picture of the Semper Augustus. This tulip is famous for being the most expensive tulip sold during the tulipomania in the Netherlands in the 17th century. The highest sums were traded in speculation over bulbs producing the striped or variegated varieties, but the underlying cause wasn’t superior genetics. Read this post by Suzi Claflin on the Direct Transmission blog that describes the virus that caused the hullabaloo.

It isn’t all elaborate chemistry and genetics behind the colors plants use. The most interesting expressions of color are the polish of shine and the shimmer of iridescence, where the illusions are a trick of physics. For more on what this is, check out Anne Osterrieder’s post on structural color on the AoB blog. It may seem like something from science fantasy, but this earthly phenomenon is real and the research subject of Dr. Heather Whitney as she writes in this blog post. The shiniest living things on Earth are the fruit of Pollia condensate. As Ed Yong writes on his Not Exactly Rocket Science blog, they look more like Christmas decorations than edible fruit. Even certain seaweeds and algae are iridescent as illustrated in this post on the Coastal Pathogens blog by Michiel Vos.

Pollia condensata Credit: Juliano Costa via Wikipedia

For some plants, a single color is not good enough, and they change color when environmental conditions change. The most familiar of these is the spectacular display deciduous forests put on each autumn. I’ve written about the biochemistry behind that event on this blog previously. Gardeners may also be familiar with the fickle hues of hydrangeas. Read this post at the Reaction of the Day blog for a refresher on pH and this plant’s pigments. Poinsettias are also good at telling the pH as described in this post at the Compound Interest blog.

Hydrangeas in France Credit: Ookwormbay7 via Wikipedia

Plants are only one class of photosynthetic organism, but they are far from the only ones prone to pageantry when it comes to pigments. Remember the horse of a different color from the Emerald City in Oz? The cyanobacterium Fremyella diplosiphon is a real-life version that changes its color based on its environment. If you’re curious how and why they do it, check out my post from earlier this week. Even on a macroscopic scale, there is plenty of algal color diversity to be found under the sea as shown on this post by Michiel Vos on the An Bollenessor blog.

I think this linkfest has literally spanned the spectrum on the use of color by photosynthetic organisms. If you enjoyed this month’s Berry Go Round, check back next month for the next edition at the Roaming Naturalist’s blog exploring important backyard plants.

UPDATE: Be sure to check out this link from Jessica Budke at Moss Plants and More. It’s not just about the color plants use, but the colors plants ‘see.’ And this latest post from The Botanist in the Kitchen blog about botanical dyes.

Johnna

The Twelve Days of Christmas Plants: Oranges

This series of posts will highlight the plants that help you celebrate the Yuletide season.

If you have made any New Year’s resolutions to be healthier in 2014, hopefully today’s topic will inspire you. Citrus fruits of all kinds are bountiful in winter and have worked themselves into our Christmas traditions. Many receive an orange in the bottom of their stocking for Christmas. There’s even a tear-jerker short story about The Christmas Orange. The Orange Bowl will be played tonight.* Thankfully, oranges and other citrus products are no longer extravagant seasonal luxuries. However, this time of year they are at their peak if you live where they can be locally grown. If you are looking for healthy snacks to atone for your holiday dietary indiscretions, citrus is a great place to start. Here’s more on the science behind the citrus.

Orange blossom and oranges. Taken by Ellen Levy Finch (en:User:Elf) March 23, 2004. Originally uploaded on English Wikipedia.

First, let’s start with some numbers:

Citrus production is a $3 billion market in the United States. That’s more than 11 million tons of citrus. Not surprisingly, Florida is the leading citrus-producing state (63% of US production totals) followed by California (34%), Texas and Arizona (3% combined). Despite our demand for this healthy fruit and citrus juice products, the market is not on the rise. Florida’s yields in both production and value have been losing ground in recent years (down 9% between the 2011/12 and 2012/13 seasons). Keep reading for more on the reason why.

Of course, it’s not just Christmas Oranges. Citrus fruits include lemons, limes, grapefruit, tangerines, pomelos and a slew of other varieties and hybrids. We eat these healthy whole foods because they are a good source of Vitamin C, but they don’t have a monopoly on this nutrient. Check out this list.** Citrus derives its name from the high content of citric acid, the pucker-inducing chemical that gives the fleshy fruit their distinctive sour taste. Of course, the distinctive smell of citrus comes from volatile chemicals stored in special glands in the peel. The main ingredient is a chemical called limonene. And what about their signature color? All immature citrus fruit goes through an immature green phase. There are chloroplasts within the cells of the peel layer of the fruit that supply energy to the developing tissue. At some point in the developmental program of citrus fruit ripening (triggered by colder temperatures), these chloroplasts undergo a major metamorphosis. They completely rearrange their membrane structure, shut down their photosynthetic machinery and kick carotenoid pigment production into overdrive to give the ripening fruit its characteristic yellow, orange or pink peel.

Orange Sections from Wikipedia

I know you’re not supposed to, but let’s compare apples and oranges. Apples and other stone fruit contain a continuous mass of fleshy fruit surrounding the seeds. Oranges and other citrus fruit have segments, seemingly arranged for convenient consumption. Have you ever wondered where these segments come from? Let’s talk about hesperidium (plant biology word of the day meaning citrus fruit type) development from the outside in. The peel and white pith layers surround a chamber called the locule. This chamber is where the seeds will form and is initially filled with air. As the fruit develops, the hair cells grow from the tissue enclosing the locules toward the center of the fruit. These hair cells swell with water, sugar and other flavor molecules as the fruit matures to become the juice sacs within the segments. Each locule is a separate segment of the hesperidium. Check out this graphic and description from the Mildred E. Mathias Botanical Garden at UCLA.

Satsumas From Wikipedia

One of my favorite citrus fruits is the Satsuma (Citrus unshiu), a seedless variety that is cold hardy enough to be grown in the Baton Rouge area.  It’s very similar to mandarin oranges or clementines- small, sweet, seedless and easy to peel***. If you are interested in trying them, but have the misfortune of living in a USDA hardiness zone less than about 8a you can order them online from places like Simon Citrus Farm or LaLagniappe. For those of you in Louisiana that would like to grow your own, I recommend checking out the LSU Agcenter citrus portal for more info.

Now, if you were interested enough to click on the Satsuma-ordering links above, you would have noticed bold disclaimers about quarantines and shipping restrictions. Don’t worry, you don’t have to fear for your safety, but you do if you are a citrus tree. This is because citrus trees have some formidable pathogens that growers and researchers are working hard to combat. Diseases like Sweet Orange Scab and Citrus Canker cause cosmetic damage to the fruit and reduce yields. Sweet Orange Scab is caused by a fungus (Elsinoë australis), and Citrus Canker is a bacterial disease (Xanthomonas citri). Both of these pathogens infect many citrus varieties. Fungicide application protocols can be used to control Sweet Orange Scab, but quarantine and local disposal of infected tissues are also key strategies to prevent their spread.

Citrus greening diseased mandarin oranges Credit: D-USGOV-USDA-ARS. T.R. Gottwald and S.M. Garnsey via Wikipedia

The most devastating pathogen for citrus growers is the bacterium Candidatus Liberibacter spp, which causes Citrus greening disease. It leaves the fruit half green and turns it inedibly sour and bitter. Eventually, the entire tree is killed. The bacterial pathogen is transmitted by an insect vector and growers must spray increasingly more pesticides and destroy acres of infected trees to control the spread of this disease. These factors (reduced supply and increasing costs of maintaining the orchards) are wreaking havoc on the citrus industry, especially in Florida. Growers and scientists are working fervently to come up with some solutions to save the citrus industry. One controversial option is introducing transgenic oranges with resistance to Citrus greening disease. The struggle of associating this wholesome fruit with the GMO debate has been eloquently covered in an article by Amy Harmon in ‘A Race to Save the Orange by Altering Its DNA.’  Genetic engineering may be the only strategy able to combat the disease on a timescale that can save the industry, as evidenced from this quote in the article.

“An emerging scientific consensus held that genetic engineering would be required to defeat citrus greening. “People are either going to drink transgenic orange juice or they’re going to drink apple juice,” one University of Florida scientist told Mr. Kress.”

Let’s hope that growers and scientists can come up with a reasonable solution to this epidemic before the Christmas Orange tradition becomes nothing more than a footnote of Yuletide folklore.

Johnna

*This year’s match-up is Ohio State and Clemson. While I have some University of Michigan connections, I may still have to root against Clemson because I am still bitter about their win over LSU in the 2012 Chick-Fil-A bowl.

** Broccoli and kiwi have nearly twice the Vitamin C content.

***Ease of peeling is a highly desirable trait for the fresh fruit market. Who wants to spend a lot of energy tearing into the fruit, ripping most of it to shreds while getting squirted in the eye with acidic juice in the process? Varieties like Satsumas and Clementines have very thin pith layers that make it easy to pull apart the peel from the segments. For other citrus fruits, the peeling process is not so easy and it frustrates fresh fruit eaters and processors alike. Don’t worry, scientists are on it. Check out this review on orange peeling technologies.

References and Links:

http://www.nass.usda.gov/Publications/Todays_Reports/reports/cfrt0913.pdf

http://www.nass.usda.gov/Statistics_by_State/Florida/Publications/Citrus/cit/2013-14/cit1213.pdf

http://en.wikipedia.org/wiki/Citrus

http://en.wikipedia.org/wiki/Orange_%28fruit%29

http://en.wikipedia.org/wiki/Limonene

http://www.botgard.ucla.edu/html/botanytextbooks/economicbotany/Citrus/

http://aggie-horticulture.tamu.edu/syllabi/422/422lab3.htm

http://en.wikipedia.org/wiki/Satsuma_%28fruit%29

http://www.lsuagcenter.com/en/crops_livestock/crops/citrus/Citrus+and+Freezing+Temperatures.htm  

http://www.lsuagcenter.com/NR/rdonlyres/0AD09A71-2C58-40BB-88DB-3D75F2A82C56/74234/pub3169CitrusScabsHIGHRES.pdf

http://www.lsuagcenter.com/NR/rdonlyres/4A42C4A3-BB1B-4DAF-91C3-FB4B675BC393/94853/pub3269citruscankerfactsheet.pdf

http://en.wikipedia.org/wiki/Citrus_greening

http://www.lsuagcenter.com/en/crops_livestock/crops/citrus/How+to+scout+for+the+asian+citrus+psyllid+and+greening+disease.htm

http://www.npr.org/blogs/thesalt/2013/12/27/257632396/time-is-running-out-to-save-floridas-oranges

http://www.nytimes.com/2013/07/28/science/a-race-to-save-the-orange-by-altering-its-dna.html?pagewanted=all&_r=0  

The Twelve Days of Christmas Plants: Peppermint

This series of posts will highlight the plants that help you celebrate the Yuletide season.

From candy canes to lattes, peppermint just tastes like winter. Here’s more on the flora behind the flavor.

Peppermint Candy

Peppermint Candy (Photo credit: Enokson)

Peppermint is a sterile hybrid (Mentha × piperita) of watermint (Mentha aquatic) and spearmint (Mentha spicata). Even though it doesn’t produce seeds, it is a prolific propagator via vegetative growth of stolons (plant biology word of the day). In the case of mint, stolons are runners of the root system just below the soil surface that can establish their own root system and plant. Because mint is very good at this, it can be quite invasive once it gets established. For your home herb garden, I would suggest growing it in a container to keep it corralled. For commercial production, certified disease-free rootstocks are used and continue producing good yields of high quality oil for about four years.

Mint leaves.

Mint leaves. (Photo credit: Wikipedia)

The Pacific Northwest wins for mint production because conditions in Washington, Oregon and Idaho are ideal for producing high quality oil. Oregon leads the U.S. in peppermint production, but Washington produces the most total mint oil (from both peppermint and spearmint). Candy canes and other seasonal candy represent a small sector of mint oil demand. The majority of mint oil (90%) is split equally for flavoring of chewing gum and dental products (toothpaste and mouthwash). Altogether, mint oil is big business worth approximately $200 million annually.

English: Skeletal diagram of menthol

English: Skeletal diagram of menthol (Photo credit: Wikipedia)

The distinct peppermint flavor is a mixture of chemicals that the plant makes and stashes in specialized structures called glandular hairs on its leaves. These volatile aromatic compounds are readily distilled into concentrated oils. We may associate the flavor with winter, but mint is harvested in the summer. The fields are mowed down, dried, then the plant material is steam-distilled to extract the oil. The main ingredient is menthol, but peppermint flavoring is a complex mixture of this ingredient with numerous other molecules. Chemists may have figured out synthetic menthol production, but oil distilled from peppermint plants is still the method of choice for flavoring production.

Because peppermint plants could care less about what our candy canes and lattes taste like, there are scientists dedicated to understanding the biochemical pathways behind the plant’s unique flavor so we can produce more of it. Mark Lange and Rodney Crouteau at the Institute of Biological Chemistry at Washington State University (Pullman) have been studying the production of natural plant products like terpenoids (bonus plant biology word of the day), which includes mint flavorings. These scientists have been working with growers and processors to increase mint oil yields and quality. Developing a biosynthetic map of the chemistry that plants use to make their aromatic compounds provided a framework for generating superior peppermint that produces more and better oil. The strategy involves transgenic technology to reduce the enzymes that would make less desirable chemical compounds and increase the enzymes that produce more desirable compounds. Because these are specialized plant chemicals, the genes are all from plants and mainly reconfigurations of the peppermint’s own DNA. Because peppermint plants are sterile, there is minimal risk of these transgenes escaping into neighboring non-transgenic plants. Also, because the commercial peppermint product, the essential oil, is a concentrated extraction of just the chemicals, there is virtually no chance any altered DNA or foreign proteins (GMO) enter the consumed products. Nevertheless, it is sometimes necessary to mark in some way transgenic-derived oils. For this purpose, an enzyme was introduced to produce (+)-limonene, a compound classified as ‘generally recognized as safe’, which can serve as a chemical marker for transgenic mint oil without affecting yield or quality. Because classical breeding techniques are not applicable to peppermint plants, these transgenic solutions offer a way to keep our domestic mint competitive in a global market.

Chewing gum, toothpaste and mouthwash have made mint flavoring an everyday occurrence, but there is a physiological reason that peppermint is the flavor of winter. It turns out that the cooling sensation of mint (think breath mints or menthol chest rubs) is not just a marketing gimmick. The main peppermint flavor ingredient, menthol, activates TRPM8 (aka Transient Receptor Potential cation channel subfamily M member 8), which is involved in neuronal signaling of cooling sensations. The action of TRPM8 (a channel that allows for the flux of cations like calcium) is part of the biochemical basis for how mammals sense temperature, innocuous cooling specifically. Because menthol triggers TRPM8 into action at warmer temperatures than it normally would, it makes us feel like we are cooler than we actually are.

So, chew on that for a while; that’s a lot of seasonal science to swallow.

Johnna

References and Links:

http://en.wikipedia.org/wiki/Peppermint

http://oregonstate.edu/dept/coarc/peppermint-0

http://www.tri-cityherald.com/2012/09/24/2112172/washington-is-no-1-mint-oil-producer.html

http://www.marketsize.com/blog/index.php/2013/05/24/peppermint-oil/

http://usmintindustry.org/Resources/MintProducts.aspx

http://www.wrigley.com/global/about-us/mint-production.aspx

http://public.wsu.edu/~lange-m/Research.htm

http://public.wsu.edu/~lange-m/Research1_1.htm

http://www.ncbi.nlm.nih.gov/pubmed/16201403?dopt=Abstract

http://www.pnas.org/content/108/41/16944.full

http://onlinelibrary.wiley.com/doi/10.1111/j.2042-7158.1994.tb03871.x/pdf

http://pubs.acs.org/doi/full/10.1021/cn300193h

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3295897/

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3119154/

http://www.ncbi.nlm.nih.gov/pubmed/7529306

The Twelve Days of Christmas Plants: Chestnuts

This series of posts will highlight the plants that help you celebrate the Yuletide season.

“Chestnuts roasting on an open fire

Jack Frost nipping at your nose

Yuletide carols being sung by a choir

And folks dressed up like Eskimos”

The Christmas Song


American Chestnut Nuts with Burrs and Leaves. ...

American Chestnut Nuts with Burrs and Leaves. Photo by myself: Timothy Van Vliet 2004 from my Orchard in New Jersey (Photo credit: Wikipedia)

The lyrics to The Christmas Song were written during the summer of 1944 and recorded by Nat King Cole in 1946. They were meant to be the acme of the spirit of the winter season. How much do you know about the tree behind the tradition? The American Chestnut’s story of loss and the brink of hope seems almost too fitting for the Christmas season.

By the time those lyrics were written, the American Chestnut (Castanea dentata) was nearing extinction. The forests of the Eastern United States were once filled with this fast-growing species with numerous specimens reaching nearly 100 feet tall and 10 feet in diameter. It provided sustenance for deer, turkeys, bears and passenger pigeons. Its wood was used for a variety of purposes since it was both lightweight and strong. Logging was not the cause of the demise of the American Chestnut.

American Chestnut, Central Maryland. Photograp...

American Chestnut, Central Maryland. Photograph supplied by the United States Forest Service. (Photo credit: Wikipedia)

English: Range map of American chestnut (Casta...

English: Range map of American chestnut (Castanea dentata). (Photo credit: Wikipedia)

In 1904, American Chestnuts in the Bronx Zoological Park were reportedly dying, infected with a Chetsnut blight fungus (Cryphonectria parasitica). It was determined that this pathogen had been imported to the United States along with chestnut trees from Asia. Because those varieties had long coexisted with the fungus, they had immunity to the disease, but our American Chestnuts were woefully susceptible. By the 1940s, the fungus had spread throughout the entire range of the American Chestnut. Once infected, the trees died within a decade as the fungus cuts off the lifeline connecting the photosynthetic leaves to the rest of the tree. Because the fungus didn’t completely kill all the roots, the trees vainly sprouted new shoots from the stumps, but eventually these too would fall victim to Chestnut blight. By 1950, nearly 4 billion trees were dead. The loss of the American Chestnut not only changed a Christmas tradition, but also drastically altered the composition of our Eastern forests as slower-growing species like oaks began to fill the empty ecological niche.

Very few specimens of American Chestnuts survive today, and their discovery is always newsworthy. Adult trees have been identified in Ohio, Tennessee, Alabama, Kentucky, Pennsylvania and Georgia. These specimens have escaped infection for a variety of reasons including micro-niche conditions and possibly superior genetics. The largest stand of American Chestnuts can be found in West Salem, Wisconsin. These were planted by an early settler in the area, and because they are outside the natural range of the American Chestnut, they largely escaped the blight. However, in 1987 scientists discovered that even these trees had become infected, and they have been the focus of intense research efforts to save them.

A number of different strategies are being used to ensure that the American Chestnut does not permanently disappear. The American Chestnut Foundation is coordinating restoration efforts. One strategy involves back-crossing American Chestnuts with the blight-resistant Chinese Chestnut. By crossing these two varieties, disease-resistance is conferred. These offspring are then back-crossed to the American Chestnut six more times, selecting for blight-resistance along the way. By 2005 the program had yielded the first blight-resistant chestnuts that were 15/16ths American Chestnut. Because these offspring are 94% American Chestnut, they retain many of the properties of this species. These are being re-introduced in test plots by the U.S. Forest Service. As of this year, nearly 80% of the back-crossed saplings are surviving. Other breeding studies are being conducted with the remaining wild specimens of American Chestnut trees.

chestnut

More modern technologies are even being applied for the salvation of the American Chestnut. In an NSF-funded project, the genomes of various tree species including the American and Chinese Chestnuts have been sequenced in order to identify the specific genes involved in blight-resistance. This knowledge will provide better genetic markers for screening in traditional breeding programs as well as target genes for engineering. To facilitate these efforts, researchers have developed new techniques for propagating and transforming American Chestnut plant material. As scientists learn more about plant disease resistance in other plant species (like crop plants), those genes also become candidates for engineering into the American Chestnut. For example, transgenic American Chestnuts containing a gene from wheat that helps confer resistance have been planted for field tests. Hopefully the genome of the Chinese Chestnut will reveal additional resistance genes that can be introduced transgenically.

Scientists are also using other methods to tame the Chestnut blight fungus. One way to combat the microbe that felled the giant trees is by using another microbe- a naturally-occurring virus that attacks the Chestnut blight fungus. This is a method that may save mature trees already infected with the fungus like those in West Salem, Wisconsin. It works to heal infected trees in a way similar to modern human vaccinations. Scientists isolate the virus from other infected American Chestnuts and inoculate blight-infected trees. The virus weakens the fungus enough so that the trees can recover. The initial results have proven promising, but this is not the magic bullet solution that they were hoping for.

With all of these efforts, roasting chestnuts over an open fire may once again be a common American Christmas tradition, but science still has a long way to go to bring this species back from functional extinction. Even then, it remains to be seen whether crossbred or transgenic (aka GMO) American Chestnuts will be accepted by the general public. However, there does seem to be some poetic justice in a restoration solution that involves a small piece of foreign DNA to protect these giant trees from a foreign deadly microbe.

Johnna

References and Links:

http://dendro.cnre.vt.edu/forsite/paul/paul1.htm

http://en.wikipedia.org/wiki/American_chestnut

http://www.esf.edu/chestnut/background.htm

http://www.fs.fed.us/r8/chestnut/qa.php

http://dnr.wi.gov/wnrmag/html/stories/2002/aug02/chest.htm

http://aobblog.com/2013/10/american-chestnut-returns/

http://www.acf.org/pdfs/education/TheLegendoftheAmericanChestnutTree.pdf

http://www.acf.org/pdfs/about/restoration.pdf

http://www.acf.org/pdfs/news_room/Blight%20Resistance.pdf

http://blogs.usda.gov/2013/12/06/restoration-efforts-may-mean-more-chestnuts-roasting/

http://phenomena.nationalgeographic.com/2013/03/11/resurrecting-a-forest/

http://www.esf.edu/chestnut/genes.htm

http://www.esf.edu/chestnut/tissue-culture.htm

http://www.fagaceae.org/outreach

http://www.nature.com/news/plant-science-the-chestnut-resurrection-1.11504

Be thankful for corn

Turkey day is finally here. What food will we be talking about today? Surprise- it’s not turkey. This is a plant science blog. I’ve gone this long without talking about animals*, and I don’t plan on starting now. So what’s the most important plant contributing to your Thanksgiving dinner? It’s corn of course!

Indian corn

Indian corn (Photo credit: Wikipedia)

In fact, a successful corn harvest by the Pilgrims in their first year was the main reason for having the first Thanksgiving feast. This success was largely due to help provided by Native Americans. It seems that corn is just as important to our modern Thanksgiving feasts. You are probably enjoying homemade cornbread stuffing/dressing**, creamed corn, and corn casserole. Plus, corn was probably the main grain ingredient in the feed your turkey ate during its short life before Thanksgiving. Also, corn products like corn syrup and other sweeteners are key ingredients in your desserts. Enjoy these corny facts on turkey day.

We may call it corn today, but it is traditionally called ‘maize’ from the Spanish form of the indigenous name maiz. The Latin genus species nomenclature for corn is Zea mays.

Maize diagram

Maize diagram (Photo credit: IITA Image Library)

You won’t find corn growing wild anywhere (maybe only from accidental germination of stray kernels). It has long been domesticated as an agricultural plant from the wild relative teosinte.

English: Teosinte, Teocinte or Teocintle from ...

English: Teosinte, Teocinte or Teocintle from the Etnobotanical museum, Oaxaca, México. (Photo credit: Wikipedia)

Typical corn plants are 8 feet tall.

The average ear of corn contains about 800 kernels in 16 rows.

The maize genome has been completely sequenced. It has approximately 2.3 gigabases and 32,000 genes.

Approximately 80 million acres of corn is planted every year in the U.S worth more than $60 billion.

Corn growing, Minnesota, USA

Corn growing, Minnesota, USA (Photo credit: Wikipedia)

Today’s U.S. corn yields are more than 120 bushels per acre.

The U.S. is the world’s largest producer of corn accounting for more than 32% of the world’s crop.

The state with the highest corn production: Iowa

This makes the U.S. the largest exporter of corn, amounting to 40 – 60% of the world’s supply, but this is only a small percentage of total U.S production.

Animal feed is the main corn product accounting for 38% of the U.S. corn crop. Surprised? It takes 6 pounds of corn to produce 1 pound of beef and 3.5 pounds of corn to make 1 pound of pork. So yeah, you do the math.

It’s not all about the animals though. American humans consume about 25 pounds of corn annually.

Corn (29% of the annual crop) is also used to make the ethanol that is added to our gasoline fuel as well as in other non-food household products like paints, crayons, fireworks, shoe polish and drywall.

88% percent of the corn grown in the U.S. is GMO with either insect-resistant, herbicide-resistant traits or both (stacked).

Check out more corny facts here.

Johnna

*OK, those of you devoted followers with an attention to detail know that statement isn’t entirely true because of this and this, but those were at least photosynthetic or trying to be.

**Another highly processed guilty pleasure of mine is boxed StoveTop stuffing. Please don’t judge, and don’t worry there is always a homemade cornbread stuffing version as well. And while we’re on the subject, I thoroughly agree with Alton Brown in thinking that stuffing is somewhat of an abomination. It weirds me out a little because of cross-contamination issues, but then again I enjoy things like Turducken and lots of pork combinations. Nevertheless, I am perfectly happy being a hypocrite on this. So technically speaking, dressing, which is cooked separate from the bird, is what I prefer on Thanksgiving.

References:

http://www.history.com/topics/thanksgiving  

http://www.history.com/news/hungry-history/indian-corn-a-fall-favorite

http://en.wikipedia.org/wiki/Corn

http://en.wikipedia.org/wiki/Teosinte

http://www.ers.usda.gov/topics/crops/corn.aspx#.UpajoOIliiQ  

http://www.epa.gov/oecaagct/ag101/cropmajor.html

http://www.ncga.com/upload/files/documents/pdf/WOC%202013.pdf

http://www.americasfarmers.com/learn-about-farming/corn/

http://www.ncga.com/home

http://www.campsilos.org/mod3/students/index.shtml

Pumpkins: Decorative, Delicious, Humongous, High-flying

Yesterday’s post on spooky plants may have introduced you to some new species, but everyone knows that the king of Halloween plants is the pumpkin. Every October we invite these squash onto our porches and into our homes to serve as decorations of the season.

There’s the traditional Jack O’ Lantern style:

English: Friendly pumpkin Svenska: Vänlig pumpa

English: Friendly pumpkin Svenska: Vänlig pumpa (Photo credit: Wikipedia)

This is one to ensure few trick-or-treating visitors:

Here’s a sophisticated arrangement that Martha Stewart would be proud of:

Here’s something for the crowd that appreciates inappropriate humor:

Rouge vif d‘Etampes

Rouge vif d‘Etampes (Photo credit: flora.cyclam)

But pumpkins are more than just a pretty face, Curcubita pepo is actually a very interesting plant. There are dozens of varieties with traits that make them useful for many different purposes. Some are small and very sweet making them ideal for baking into pies like the Amish Pie or Baby Pam Sugar Pie. Others like the Rouge vif D’Etampes (aka Cinderella) are equally useful for carriages, cooking and still life painting models. Also, not all pumpkins are orange. The Marina Di Chioggia variety is a blue-green color with knobby skin. It looks atypical, but is still quite delicious.

English: Marina Di Chioggia squash grown in th...

English: Marina Di Chioggia squash grown in the California low desert (Photo credit: Wikipedia)

pumpkin at a competitive weigh-off in California.

pumpkin at a competitive weigh-off in California. (Photo credit: Wikipedia)

Pumpkins also represent the world’s largest fruit, botanically speaking, that is.* The world’s largest pumpkin weighed in this year at 2032 pounds in Morgan Hill, CA. Now, that’s a great pumpkin! It takes about 100 days for the pumpkin to reach that size and the farmer calculated that at one point, the pumpkin was gaining 50 lbs a day. That’s a superphotosynthesizer indeed.

What are the secrets to growing a pumpkin as big as a smart car? It all comes down to a combination of nature and nurture. You need to start with seeds that have been bred for producing large pumpkins. Dill’s Atlantic Giant is a good variety and fierce competitors on the giant-pumpkin-growing circuit have paid as much as $1600.00 per seed from record-setting specimens. That’s a pricey investment you may think akin to Jack’s magic beans, but the prize for growing the year’s largest pumpkin can be $10k – $30k! Once you’ve planted your genetically superior pumpkin seeds be sure to pamper them with the finest of nutrients to support maximal growth. Some competitive growers swear by secret compost mixtures, but any nutrient-rich fertilizer will do. Multiple pumpkins will begin forming along the vines, but the best strategy involves culling the multiple developing fruits down to a single pumpkin. It’s always risky putting all of your eggs into one basket, but in this strategy the entire green plant will devote all of its resources into growing that single pumpkin. If you want a perfectly shaped pumpkin, roll it every week or so during the growing season to ensure roundness. Just be careful not to damage the vine feeding your pumpkin and be ever vigilant for pests like the dreaded squash vine borer.

Sheer size isn’t the only extreme when it comes to pumpkin traits. A modern fall tradition has spawned a new niche market for specialty pumpkins of a much smaller size capable of withstanding enormous pressures without exploding. I’m referring, of course, to Punkin Chunkin.

Punkin Chunkin

Punkin Chunkin (Photo credit: vpickering)

During this annual event** teams of garage tinkerers and self-proclaimed engineers*** take to a field in Delaware with homemade machines designed to launch a pumpkin as far as the laws of physics allow. There are multiple classes based on the type of instrument: air gun, centrifugal, catapult and trebuchet. Of course, there are many factors that contribute to a win for having chunked a pumpkin the longest distance, but all else being engineered properly the limiting factor is the pumpkin itself. The elusive goal for Punkin Chunkers is the 1 mile mark, but the mathematics just isn’t in favor of hurling a pumpkin that far by any means. Simply, the agricultural history of the pumpkin has not naturally selected for pumpkin sturdy enough to withstand the pressures associated with breaking the sound barrier, which is about the necessary velocity a pumpkin must reach to travel a mile by some calculations. According to the official rules of Punkin Chunkin, only 8 – 10 lb specimens of the listed varieties are allowed (Yes, competitors must provide their own pumpkins), and pumpkins must remain intact until they land on the ground. Thus, horticultural savvy is an important component in pumpkin distance world records. The Yankee Siege team has its own ten commandments when it comes to selecting pumpkins for chunking. The consensus is that smooth, white pumpkins that are nearly spherical are ideal for distance, and Lumina is the choice variety of veteran chunkers. It’s difficult to say whether Luminas are at their genetic limit for sturdiness, but the rules of Punkin Chunkin do not explicitly prohibit GMOs. Perhaps if some plant scientist were so inclined, Lumina pumpkins could be genetically engineered to have a calcite or silica shell like those of some phytoplankton for added stability. No more naked pumpkin ammo for these guns. It’s time for a bio-inspired shell casing. As you can see, the Kickstarter campaign practically sells itself.

starr-091003-7558-plant-Cucurbita_pepo-White_L...

starr-091003-7558-plant-Cucurbita_pepo-White_Lumina_pumpkin-Maui_County_Fair_Kahului (Photo credit: Starr Environmental)

Happy Halloween everyone!

Johnna

*Fruit is the fleshy structure that holds the seeds of plants. The way that we typically use the terms fruits and vegetables in everyday language (say, when trying to get your picky four-year-old to eat them) are more of an arbitrary culinary designation.

**This year’s takes place this weekend. It should be noted that the event isn’t all pumpkin guts or glory. The event generates ~$80K for charities like St. Jude’s Research Hospital.

***To be fair, many contestants are actual engineers.

References:

http://www.kew.org/plants-fungi/Cucurbita-pepo.htm

http://www.allaboutpumpkins.com/varieties.html

http://www.latimes.com/science/sciencenow/la-sci-sn-science-of-biggest-pumpkin-20131015,0,2497209.story#axzz2j2nO3aRL

http://www.smithsonianmag.com/science-nature/The-Great-Pumpkin.html

http://extension.oregonstate.edu/gardening/how-grow-monster-pumpkin-0

http://www.marketwatch.com/story/the-1600-pumpkin-seed-2013-10-29

http://www.washingtonpost.com/wp-dyn/content/article/2005/10/14/AR2005101402126.html

http://boards.straightdope.com/sdmb/showthread.php?t=632675

http://scienceblogs.com/dotphysics/2009/11/20/punkin-chunkin-they-will-never-make-a-mile-range/

http://www.yankeesiege.com/HowToWin.html