August 24, 2010, 7:08 AM CT

Understanding root and seedling development

A biosensor utilizing black platinum and carbon nanotubes developed at Purdue University will help give researchers a better understanding of how the plant hormone auxin regulates root growth and seedling establishment.

Marshall Porterfield, an associate professor of agricultural and biological engineering and biomedical engineering, created a new sensor to detect the movement of auxin along a plant's root surface in real time without damaging the plants.

The nanomaterials at the sensor's tip react with auxin and create an electrical signal that can be measured to determine the auxin concentration at a single point. The sensor oscillates, taking concentration readings at different points around a plant root. An algorithm then determines whether auxin is being released or taken in by surrounding cells.

"It is the equilibrium and transport dynamics that are important with auxin," said Porterfield, whose findings were reported in the early online version of The Plant Journal.

A current focus of auxin research is understanding how this hormone regulates root growth in plants growing on sub-optimal soils. Angus Murphy, a Purdue professor of horticulture and the paper's co-author, said that worldwide pressure on land for food and energy crops drives efforts to better understand how plant roots adapt to marginal soils. Auxin is a main hormones involved in that adaptive growth......... Posted by: Erica      Read more         Source

August 8, 2010, 11:45 PM CT

Flower-Dwelling Yeast

A beneficial yeast that tolerates fungicide may offer a "one-two punch" against Fusarium graminearum, the fungal culprit behind Fusarium head blight ("scab").

U.S. Department of Agriculture (USDA) and Ohio State University (OSU) researchers isolated an improved variant of the yeast Cryptococcus flavescens about two years ago, and are evaluating its potential as a biocontrol agent.

In susceptible wheat and barley varieties, scab-afflicted kernels appear shrunken and chalky-white. The fungus can also produce a mycotoxin that can diminish the grain's value or make it less safe to eat.

Spraying fungicide can reduce scab by 50 to 60 percent; however, farmers are mandatory to stop using the chemicals soon after wheat starts to flower. Eventhough this measure keeps fungicide residues to a minimum, it can leave the grain vulnerable to new invasions by the scab fungus, notes David Schisler, a plant pathologist with USDA's Agricultural Research Service (ARS). He works at the ARS Crop Bioprotection Research Unit in Peoria, Ill. ARS is USDA's chief intramural scientific research agency.

Since 1998, he has teamed with OSU professor Mike Boehm and others to exploit the ability of some microorganisms to outcompete F. graminearum for space and nutrients in wheat's flowers and seed heads......... Posted by: Erica      Read more         Source

August 8, 2010, 11:31 PM CT

As crops wither in Russia's severe drought

As the fate of Europe's largest collection of fruit and berries hangs in the balance of a Russian court decision, the Global Crop Diversity Trust issued an urgent appeal for the Russian government to embrace its heroic tradition as protector of the world's crop diversity and halt the planned destruction of an incredibly valuable crop collection near St. Petersburg. Pavlovsk Experiment Station is the largest European field genebank for fruits and berries, and is part of the N.I. Vavilov Research Institute of Plant Industry, where Russian researchers famously starved to death rather than eat the seeds under their protection during the 900-day siege of Leningrad during World War II.

At issue is an effort by residential real estate developers to build houses on land occupied by Pavlovsk Station. The take-over would involve bulldozing Pavlovsk's field collections amassed over the last centurycollections that contain thousands of varieties of apples, strawberries, cherries, raspberries, currants and other crops90 percent of which are not found anywhere else in the world.

"It is a bitter irony that the single most deliberately destructive act against crop diversity, at least in my lifetime, could be about to happen in Russia of all placesthe country that invented the modern seed bank," said Cary Fowler of the Global Crop Diversity Trust, which aims to ensure the conservation and availability of crop diversity for food security worldwide and supports the operations of the Svalbard Global Seed Vault in the Arctic Circle......... Posted by: Erica      Read more         Source

Mon, 09 Aug 2010 03:43:41 GMT

Prelude

The black locust trees were in bloom last weekend. We saw them clouding the roadside as we got farther south on our drive to Roundrock. I have a few locust trees in my woods, but I only happened by one of them in my tromping about then, and it wasn’t blooming. This one is on my neighbor’s property and I passed it on my way to his cabin to get some water (ours having all leaked out on the drive down, which I think I told you about). Although black locust is believed to have been native to parts of Missouri, its original range was more prominently in Appalachia. Now it is considered naturalized throughout the country and is even considered a pest in many places.

The Beltane edition of the Festival of the Trees is up over at Nature’s Whispers, and a fine collection it is. So scurry over there if you haven’t to see all of the links Jasmine has collected.

The next edition, number 48 in the ongoing series, will be hosted by CJ at Wandering Owl Outside. His general theme is the relationship between trees and game animals/birds, though he has said he’ll consider any link you send his way that deals with trees. Deadline for submissions (of posts you’ve written or those you have found) is May 30. Send your links to CJHarn (at) gmail (dot) com. Be sure to put Festival of the Trees in your subject line. Or you can use the handy contact form.

You’ll recall that I taped the seams in the insulating sheathing that was wrapped around the stud frame of the cabin before the “log” siding was put on. I’ve done this to try to keep the bugs out. When I was last at the cabin, I realized that I’ll need to tape along the bottom of the framing as well, since that is at least as much of an access point. And now it occurs to me that I’ll probably need to do the same up on the ceiling (if there is any exposed seam there).

• One year ago I was looking closely at a standing stump.
• Two years ago I was looking closely at an unfortunate fish and thinking about dreams, denied and fulfilled.
• Three years ago I was looking closely at the full lake from a different point of view.
• Four years ago I was looking closely at an unexpected planting success (which I’ll never see again).

You know, I think I like your blog the best!

Missouri calender:

• Mother’s Day
• Dewberries bloom.

Posted by: Roundrockjournal      Read more     Source

Mon, 09 Aug 2010 03:24:50 GMT

Chiranthodendron pentadactylon

....and yet another thank you to frequent BPotD contributor Jim in San Francisco (aka J.G. in S.F.@Flickr) for submitting today"s set of photographs (original image 1 | original image 2 | original image 3 | Botany Photo of the Day Flickr Pool). As always, I"m grateful.

I"ve been intrigued by this species both times I have visited the Montane Cloud Forest at UC Botanical Garden at Berkeley. Who wouldn"t be curious about something known as the devil"s hand tree or monkey"s hand tree? Unfortunately, I"ve only visited this garden in early April, too early to see the "handedness" of this native of wet mixed oak-pine and deciduous mountain forests of Guatemala and Oaxaca, Mexico. All I was able to observe were last year"s aging seed pods on the ground (for photograph, see the last image on this page).

Chiranthodendron literally means "hand-flowering tree", while the epithet pentadactylon means "five-fingered" -- referring to the five prominent stamens that can be seen in these photographs. Pollinators attracted to the flowers include both bats and perching birds, particularly orioles and their relatives. Chuck B. of San Francisco writes about the sweet taste of the nectar produced by the flowers at the conclusion of his weblog post on Friday Night Botanical Garden.

A French translation of the original 1805 Spanish-written description of Chiranthodendron pentadactylon is available online thanks to the Smithsonian Library"s Digital Library: Description Botanique du Chiranthodendron by Jose Dionisio Larreátegui Two illustrative plates are included, linked from the bottom right-hand of this page.

Ethnobotany resource link: The Gwich"in Ethnobotany Database was recently launched, containing information about 47 plants used for food, medicine, shelter and tools (with photographs, video and recipes). Thank you to Dr. David Brownstein for sending along the link. Posted by: Daniel Mosquin      Read more     Source

July 16, 2010, 7:14 AM CT

How Cranberry Juice Fights Bacteria

Revealing the science behind the homespun advice, a team of scientists at Worcester Polytechnic Institute (WPI) has identified and measured the molecular forces that enable cranberry juice to fight off urinary tract infections in people.

The data is published in the paper "Direct adhesion force measurements between E. coli and human uroepithelial cells in cranberry juice cocktail," which was published on-line, ahead of print, by the journal Molecular Nutrition and Food Research. The research illuminates the basic mechanics of E. coli infections, which has implications for developing new antibiotic drugs and infection-resistant materials for invasive medical devices.

The research team led by Terri Camesano, professor of chemical engineering at WPI, focuses on the virulent form of E. coli bacteria that is the primary cause of most urinary tract infections. This strain of E. coli is covered with small hair-like projections known as fimbriae which act like hooks and latch onto cells that line the urinary tract. When enough of the virulent E. coli adhere to cells in this way, they cause an infection. Prior work by Camesano has shown that exposure to cranberry juice causes the fimbriae on E. coli to curl up, reducing their ability to attach to urinary tract cells. In the newly released study, Camesano's team presents the first specific measurements of the mechanical forces involved in the attachment of the virulent E. coli to human urinary tract cells. The study also documents how the force of attachment is reduced in the presence of cranberry juice cocktail. "This is not a clinical study-it's a mechanical study that shows us the direct forces that can lead to infection," Camesano said......... Posted by: Erica      Read more         Source

July 14, 2010, 7:40 AM CT

Rapidly-disappearing ancient plant cycads

Cycads, "living fossil" descendents of the first plants that colonized land and reproduced with seeds, are rapidly going extinct because of invasive pests and habitat loss, particularly those species endemic to islands. But new research on Cycas micronesica published recently as the cover article in Molecular Ecology calls into question the characterization of these plants as relicts (leftovers of formerly abundant organisms), and gives a glimpse into how the remaining plantsthose that survived the loss of more than 90% of their populationcan be conserved and managed. By sampling what is left of C. micronesica on Guam, researchers, including some from the American Museum of Natural History, found moderate genetic variation within local populations and different levels of gene flow between populations.

"Cycas micronesica is one of the most ecologically important plants on Guam and nearby islands, and it is now rapidly disappearing," says Anglica Cibrin-Jaramillo, a researcher at the American Museum of Natural History and at The New York Botanical Garden. "But with new genomic tools we developed microsatellite markers to quickly assess individual plants. This technique is ideal for species that need quick answers for conservation reasons." Microsatellite markers are short genetic sequences typically used to determine how individuals are correlation to each other (kinship) and other population studies......... Posted by: Erica      Read more         Source

July 13, 2010, 7:17 AM CT

Breaking biomass better

One of the challenges in making cellulosic biofuels commercially viable is to cost-effectively deconstruct plant material to liberate fermentable energy-rich sugars. The U.S. Department of Energy (DOE) is funding several projects focused on identifying enzymes in organisms that optimally degrade cellulosic feedstocks. One such source are fungi, which break down dead wood and leaf litter in forests; in fact, some pest management companies consider wood rot more destructive for homes than termites.

The DOE Joint Genome Institute (JGI) previously sequenced and published the genomes of two wood-decaying fungi. Now a team of scientists led by researchers from the DOE JGI and the University of Utrecht announce the analysis of a third such genome as per a research findings published online July 11 in Nature Biotechnology (http://bit.ly/cjkaxO). All told, DOE JGI has sequenced and annotated 40 fungal genomes, and 40 more are currently in the works.

"When we go into a forest we don't see layers of dead branches because wood decay fungi take care of them," said Igor Grigoriev, head of the DOE JGI's Fungal Genomics Program and a senior author on the study. "So when we think about bioenergy and degrading biomass and converting that into biofuel, we would like to learn the most efficient ways of doing that from fungi, which have invented a number of ways of doing that in nature. Schizophyllum commune is the second white rot fungus and third wood degrader we've sequenced. The DOE JGI sequenced the first white rot fungal genome Phanerochaete chrysosporium in 2004. Then last year we sequenced the first brown rot fungal genome Postia placenta." Postia was found to utilize a unique arsenal of small oxidizing agents that blast through plant cell walls to decompose cellulose into simple sugars......... Posted by: Erica      Read more         Source

July 9, 2010, 6:50 AM CT

Ferns and fog on the forest floor

As the mercury rises outdoors, it's a fitting time to consider the effects of summertime droughts and global warming on ecosystems. Complex interactions among temperature, water cycling, and plant communities create a tangled web of questions that need to be answered as we face a rapidly changing climate.

Drs. Emily Limm and Todd Dawson (University of California, Berkeley) recently tackled one aspect of the challenging question of how climate change can impact plant communities that obtain water from fog. Their results are reported in the recent issue of the American Journal of Botany

Fog is an important source of water to ecosystems around the world, because fog allows plants to stay hydrated even during times without rain. Fog may condense and drip to the soil, where it can be taken up by roots. Alternatively, some plants are able to absorb the water from fog through their leaves, allowing these plants to immediately benefit from the atmospheric moisture that may never reach the forest floor. The fern Polystichum munitum covers the forest floors of the redwood forests in northern California. Limm and Dawson examined variation in the ability of the leaves of P. munitum to absorb the water from fog.

The scientists observed that the quantity of water the plants absorbed varied in the different regions of the redwood forest. "Today, summertime drought conditions are greater in the southern end of the redwood forest ecosystem of Northern California, and this reduces P. munitum abundance and plant size. These smaller ferns in the south are less able to capture fog water that drips to the forest floor during the summer, and they may therefore suffer more drought stress than ferns in the northern end of the redwood forest ecosystem," Limm stated......... Posted by: Erica      Read more         Source

July 8, 2010, 6:53 AM CT

What plant genes tell us

Anyone who has seen teosinte, the wild grass from which maize (corn) evolved, might be forgiven for assuming a number of genetic changes underlie the transformation of one plant to the other.

However, a method for exploring the genetics of domestication called Quantitative Trait Locus (QTL) mapping has revealed that only modest modifications are needed to convert a wild plant to a crop plant. Some major transitions in phenotype can even be achieved by a single genetic change.

The few artificial experiments in domestication that have been conducted have also shown that it is possible to achieve domesticate-like plants in fewer than 20 generations.

None of this pleases archaeobotanists, who try to piece together the history of plant domestication from scraps of ancient plant remains.

Their data are sparse and unimpressive - a 10,000-year-old squash seed found in a cave in Oaxaca, Mexico, or four 12,000-year-old grains of rice recovered from a rock shelter in Hunan Province in China - but they have their own irrefutable reality.

"There's been an argument in the recent archeological literature that genetics gives a false picture of domestication as a rapid, geographically localized process," comments Kenneth M. Olsen, PhD, assistant professor of biology in Arts & Sciences at Washington University in St. Louis. "They argue instead that domestication likely involved much trial and error in a number of different geographic regions over a long period of time"......... Posted by: Erica      Read more         Source