Archives for the month of: May, 2013

We eat a lot of potatoes in our house.  Having a vegetarian and meat-eater in the house can make mealtimes stressful, but baked potatoes topped with broccoli for me and bacon for him makes us both happy.  I kid, but in early nineteenth century Ireland potatoes were no joke… they were the staple food for the lower class, the landless laborers.

Existing dependent on a single food source is risky and in 1845 a plant disease epidemic took out the potato in Ireland (in the field and in storage).  The disease would later be named late blight and is regarded as the disease that birthed the study of plant pathology.   The causal agent of late blight is a Phytophthora infestans (Latin for “plant destroyer”), fungal-like organism called an oomycete.  As a result of this microscopic killer, an estimated 1 million Irish starved and another 1.5 million emigrated from Ireland, dramatically changing not only Ireland but countries like the United States that received the displaced.  Late blight remains a significant threat to potato and tomato industries today (2009 epidemic in Northeast US); however, we now have management options such as fungicides and moderately resistant varieties to minimize losses.

Potato with late blight (foreground); Potato treated with fungicides (background)

Potato with late blight (foreground); Potato treated with fungicides (background)

(Image: Courtesy D. Inglis via apsnet.org)

Last week, Yoshida et al. (2013) released a study identifying the specific strain (or genotype) of P. infestans responsible for the Irish Potato Famine. Researchers isolated samples of the pathogen from preserved potato leaves with late blight symptoms and compared them to modern strains with DNA analysis.  Genotype HERB-1 was consistently isolated from the historic Irish samples, suggesting it was the strain responsible for the late blight epidemic.  HERB-1 is different from modern genotypes and is likely extinct, having been replaced by US-1 by the 20th century, as the predominate genotype outside of P. infestans center of origin (Mexico).  Researchers also note that while US-1 and HERB-1 are related, US-1 is not a direct ancestor of HERB-1.

I think one of the most interesting parts of this study was the use of preserved herbarium samples to generate the dataset.  Just think of other pathogen populations and histories that could be elucidated using this approach!  Aside from the cool factor, understanding how these pathogens evolve is vital for developing new management strategies.

 PS – For more on late blight click here.

Happy Friday!  Here are the stories I’ve been reading this week…

1. Amphibian plague

The fungus Batrachochytrium dendrobatidis (Bd, the chytrid fungus) is the causal agent of chytridiomycosis, a fatal disease of frogs.  In the May 2013 issue of EcoHealth, Grower et al. report that Bd can also infect and kill a limb-less, snake-like group of amphibians called caecilians in the wild.  Unless you’re an avid caecilian enthusiast (they’re out there), you may be wondering ‘so what’.  Adding more species to the Bd-susceptible list is notable because some researchers are hypothesizing that this fungus may cause disease in ALL amphibians.  Imagine a pathogen with the ability to infect all mammals.  The chytrid fungus has already been blamed for the extinction of nearly 300 amphibian species.  Furthermore, knowing Bd infects the soil-dwelling caecilian suggests that the pathogen is adept in soil survival.  It was previously known that Bd survives and is spread via water, thanks to its swimming zoospore.

caecilian, Natural History Museum via scientificamerican.com(Image: Natural History Museum via scientificamerican.com)

2. Cal State leaning toward virtual labs?

Officials at the California State University system are trying to solve the problem of “bottleneck courses”; those that difficult for students to get into, thus slowing their advancement or even causing them to drop out.  Some of these identified courses are required lab-based science courses for non-majors.  One solution may be to enroll students in virtual lab classes, involving simulations of experiments.  On one hand, this alleviates the bottleneck issue while still providing students with exposure to basic theories, problem-solving, scientific method, etc.  However, as Cal State professor Jeffery Bell cautions, the virtual lab may be too abstract for some students and give them a false appreciation of what scientists really do.  I have to agree and I’d hate to see lab sections for non-majors completely eliminated in favor of simulations.  There’s a “cool” factor to science (preparing a specimen and observing it under a real microscope, for example), that doesn’t quite translate to viewing something on a computer.

3. The Case of the Irish Potato Famine

I’m planning to write more about the Irish Potato Famine next week since it’s one of the great historical plant pathology stories (yes, we have those).  While the causes of the Irish Potato Famine are political as well as biological, it was announced this week that the particular strain of Phytophthora infestans, the pathogen responsible for destroying millions of potatoes in 1840’s Ireland, has been genetically identified.  This strain, known as HERB-1, was responsible not only for the deaths of an estimated 1 million people but also immigration of many Irish to the United States and other parts of Europe.  More next week…

It’s Friday!  Here are the stories that caught my attention this week:

1. Today (17 May) is Endangered Species Day and later this year we’ll mark the 40th anniversary of the Endangered Species Act which was signed into law by President Nixon on 28 December 1973.  The primary goals of this legislation are to prevent extinction of at risk species of animals and plants and mitigate threats to their survival.  Despite worldwide determination to protect these organisms, there are organized efforts to kill or maim them.  Earlier this month poachers entered the Dzanga Bai World Heritage Site in Central African Republic and killed at least 26 elephants and stripped them of their tusks.  WATCH: Environmentalist Philippe Cousteau spoke about poaching in an interview with CNN this week.   WEB_113502(Image: Elephants in Dzanga Bai via World Wildlife Fund)

2. NPR’s Morning Edition had a piece on Valley Fever this week.  Valley Fever (coccidioidomycosis) is a disease caused by a soil-borne fungus (Coccidioides immitis) found in arid climates, such as the American southwest where cases are mysteriously on the rise.  People who work outside are at highest risk of inhaling infested dust and if infections go unchecked, the fungus can spread from the lungs to the central nervous system.  Patients with severe cases may require lifelong anti-fungal medications and due to similarities between fungal and human cells (FYI: fungal cells are much more like human cells than plant cells!), the medications can result in many unpleasant side effects. This is an unfortunate reminder of how much work there is to be done in the field of medical mycology.

3. In response to the news that atmospheric carbon dioxide levels reached 400 ppm (a level unseen in the past 800,000 years), Scientific American published a piece on artificial “trees” binding CO2 from the air.  Just reading the title, my mind immediately went to Dr. Seuss’ The Lorax, which describes the consequences of world without trees.  Physicist Klaus Lackner has developed a synthetic resin that sequesters CO2, which can then be used for industrial purposes or buried underground.  An interesting option, but I agree with the article’s author, David Biello: we need to make more efforts toward lowering CO2 emissions in the first place.The Lorax(Image: Dr Seuss’ The Lorax, 2012)

 4. Finally, I wanted to share these images of sea butterflies from zoologist Karen Osborn.  Not only are they beautiful but these organisms serve as indicators of the health of our oceans. sea butterfly(Image: Karen Osborn via Smithsonian)

Honeybees play a crucial role in agriculture, and I’m not only referring to the honey that we use for baked goods and at tea time.  Sorry, Pooh Bear. Pollination of many fruit and vegetable crops is facilitated by honeybees when gathering nectar from flowers of these plants.  Only following successful pollination and fertilization of said flowers can fruits and vegetables begin to grow.  Therefore, bee population and health is directly tied to our supply of many fruits and vegetables you see in gardens, farmers markets and in grocery stores:

common crops pollinated by bees

In 2006, beekeepers and scientists became aware of a phenomenon in which honeybees appeared to abandon their hives.  In most cases, the queen was still alive and no dead bee bodies were found inside.  The name for this condition is just as mysterious: colony collapse disorder (CCD).  Prior to 2006, a beekeeper could expect to lose 1 out of 10 hives during typical winter.  Due to CCD, losses have tripled and could potentially reach 50%.

The cause(s) of CCD have not been proven, but may be related to pathogens, pests (Varroa mites are frequently associated with CCD), poor nutrition, mismanagement of hives, environmental stress (drought) and agricultural chemicals.  Recently, one class of insecticide has been “accused” of being the cause of CCD: neonicotinoids, which have been used since the 1990s on a wide variety of vegetable and field crops as a soil, seed or foliar treatment.  The evidence is mounting against neonicotinoids, causing the European Commission instituted a 2-year ban on these insecticides earlier this month.  However, many researchers are questioning the effectiveness of the ban as CCD is widely thought to have more than one causal agent.  More research is definitely required to alleviate bee shortages and secure the future of our favorite pollinators and crops.

PS – Penn State entomologists have been leading the way in pollinator research.  Talking CCD on BBC News Hour (go to 17:50).

Am I the only sucker for a top 10 list?  Or any list for that matter?  Best beaches, worst dressed, most influential, least popular??  Give me a superlative and a topic and consider me “most likely” to click on it!

Top popular science stories of the week will be a regular feature on the blog every Friday.  These are my top stories; the ones that were fascinating to me as a science enthusiast.  You may or may not agree that these were most interesting or ground-breaking.  Either way, I’d love to hear what you’ve been reading this past week!

Here they are (in no particular order):

1. Open Ag Data

The G-8 Open Data for Agriculture Conference was held last week in Washington DC.  The “open data” concept is just what it sounds like: making data freely available for scientists (or anyone, for that matter) to use.  The idea may be a little unnerving for researchers who historically are tight-lipped about their hypothesis, methods and results lest an unscrupulous competitor “steal” their ideas.  However, those of us who work in agriculture ultimately have the same goals: to provide safe and sustainable food for the world.  Having a bank of accessible data would open the doors for collaboration and innovation and makes the original research dollars stretch even further by providing more options for previously published (and potentially unpublished) data.

2. NYT covers citrus greening

I will never be able to pass up a mainstream media plant pathology story.  Citrus greening (Huanglongbing) is a destructive bacterial disease of citrus trees and has been present in Florida since at least 2005. The bacteria, Candidatus Liberibacter asiaticus, are disseminated by a tiny insect called the Asian citrus pysllid.  The article highlights some of the challenges growers are facing such as the lack of successful treatments and the impact of abandoned citrus groves (and potentially, homeowners’ backyard trees) as sinks for the insect and bacteria.  Fortunately research dollars have been ear-marked for this disease, but is the impact on Florida’s citrus industry already too great?

Citrus greening symptoms and vector_via APSnet(Image: Via APSnet.org, Tim R. Gottwald and Steve M. Garnsey, USDA, ARS, U.S.)

3.  Turning back the clock for heart tissue (video)

I’m sure most of us have been affected by heart disease in one way or another.  In age-related heart disease, there is a general decline in function as the muscle itself hardens and grows in size (myocardial hypertrophy).  Researchers from Harvard studying age-related heart disease focused their efforts on a hormone called GDF-11, which declines with age.  Surprisingly, when old mice were given doses of GDF-11 comparable to levels found naturally in young mice, old hearts returned to the size of young hearts within a matter of weeks.  This research can be found in the recent issue of Cell.

Mouse heart1_Via CBS Mouse heart2_Via CBS(Image: CBS News)

 4. Cost and profitability of organic apple production

Demand for organic produce, has skyrocketed in recent years.  As stated in this Plant Management Network article, organic apples have gone from a specialty crop to a true commodity with demand rivaling that of conventional produce.  This study compared production costs and yield in organic and conventional apple orchards in the state of Washington.  Organic management costs 5-10% more on average per acre and yields slightly less than conventional methods.  If customers remain willing to pay a premium price, organic production can be profitable for the grower.  However, in a “bad year” (i.e. heavy disease, pests or incompatible weather) both management practices may fail profit.  Ah, such is agriculture…

 

What have you been reading this week?