September 15, 2009, 9:23 PM CT

Unlocking genetic secrets of date palm

Scientists at Weill Cornell Medical College in Qatar have mapped a draft version of the date palm genome, unlocking a number of of its genetic secrets.

"We have generated a draft DNA sequence and initial assembly of the date palm using the most advanced technology," says Joel Malek, director of the Genomics Laboratory at WCMC-Q. Genetic information about the date palm is extremely valuable to scientists who are working to improve fruit yield and quality and to better understand susceptibility and resistance to disease.

"This is an important step for our biomedical research program," says Khaled Machaca, Ph.D., professor of physiology and biophysics and associate dean for basic science research. "It clearly demonstrates the feasibility and success of the most advanced genomics technologies in Qatar and represents a milestone towards establishing Qatar and Weill Cornell as a regional research center of excellence. In addition, this achievement by the WCMC-Q research team holds great promise for the application of the genomics technology to a better understanding of biomedical problems".

The date palm sequencing work was a proof of concept study, as per Malek, who established the genomics laboratory last year. The goal was to establish and validate the capabilities of the core lab for large-scale genomics projects. The lab is an integral part of a large biomedical research program launched last year by WCMC-Q with support from the Qatar Foundation that aims to make Qatar a hub for research in the Middle East......... Posted by: Erica      Read more         Source

September 15, 2009, 9:19 PM CT

Drug-free Cannabis plant

In a first step toward engineering a drug-free Cannabis plant for hemp fiber and oil, University of Minnesota scientists have identified genes producing tetrahydrocannabinol (THC), the psychoactive substance in marijuana. Studying the genes could also lead to new and better drugs for pain, nausea and other conditions.

The finding is reported in the recent issue of the Journal of Experimental Botany Main author is David Marks, a professor of plant biology in the College of Biological Sciences.

The study revealed that the genes are active in tiny hairs covering the flowers of Cannabis plants. In marijuana, the hairs accumulate high amounts of THC, whereas in hemp the hairs have little. Hemp and marijuana are difficult to distinguish apart from differences in THC.

With the genes identified, finding a way to silence themand thus produce a drug-free plant comes a step closer to reality. Another desirable step is to make drug-free plants visually recognizable. Since the hairs can be seen with a magnifying glass, this could be accomplished by engineering a hairless Cannabis plant.

The scientists are currently using the methods of the latest study to identify genes that lead to hair growth in hopes of silencing them.

"We are beginning to understand which genes control hair growth in other plants, and the resources created in our study will allow us to look for similar genes in Cannabis sativa," said Marks......... Posted by: Erica      Read more         Source

September 15, 2009, 2:45 PM CT

Exotic timber plantations use water

Ecologists have discovered that timber plantations in Hawaii use more than twice the amount of water to grow as native forests use. Particularly for island ecosystems, these findings suggest that land management decisions can place ecosystems and the people who depend on them at high risk for water shortages.

"Researchers used to believe that forests in same environments use water in the same way," says Lawren Sack of The University of California at Los Angeles, who coauthored the study with graduate student Aurora Kagawa in the recent issue of the ESA journal Ecological Applications "Our work shows that this is not the case. We need to know the water budget of our landscape, from gardens to forests to parks, because water is expensive".

Eventhough forests like these Hawaiian timber plantations can be valuable for their contributions to human society, such as fiber, fuel and carbon sequestration, they are dominated by non-native vegetation.

Kagawa, Sack and their colleagues compared the water use of trees in native forests, composed mostly of native ohia trees, with water use in timber plantations containing exotic eucalyptus and tropical ash. The team inserted heated and unheated probes into the trees' trunks and monitored the temperature differences between the two as sap flowed past them. This technique allowed them to determine the rate of sap flow through the tree. A faster flow rate means that the tree is using more water......... Posted by: Erica      Read more         Source

September 15, 2009, 2:29 PM CT

More tamarisk invasion in future

If the future warming trends that researchers have projected are realized, one of the country's most aggressive exotic plants will have the potential to invade more U.S. land area, as per a newly released study reported in the current issue of the journal Invasive Plant Science and Management The study observed that tamariskprevalent today in some parts of the region, but generally limited to warm and dry environmentscould expand its range into currently uninvaded areas.

"Results of our study suggest that a little over 20 percent of the Northwest east of the Cascade Mountains supports suitable tamarisk habitat, but less than one percent of these areas is currently occupied by the species," said Becky Kerns, a research ecologist with the Western Wildland Environmental Threat Evaluation Center (WWETAC) who led the study. "That means the remainder is highly vulnerable to invasion right now with the situation potentially getting worse as favorable conditions for tamarisk may expand under climate change".

These findings translate into a two- to ten-fold increase in highly suitable tamarisk habitat in Oregon, Washington, and Idaho by the end of the century.

Tamarisk, also known as "saltcedar," is a deciduous shrub or small tree that grows quickly, reproduces profusely, and tolerates drought and salty conditions, making it capable of easily displacing native species. It also sheds flammable leaves that serve as potential fuel, significantly increasing an area's wildfire risk. The plant was intentionally introduced to the West in the 1800s as an ornamental, windbreak, shade, and erosion control species and today can be found growing prolifically in the Northwest in the central Snake River Plain, Columbia Plateau, and Northern Basin and Range......... Posted by: Erica      Read more         Source

September 15, 2009, 7:51 AM CT

Clues into the evolution of the first flowers

Approximately 120-130 million years ago, one of the most significant events in the history of the Earth occurred: the first flowering plants, or angiosperms, arose. In the late 1800s, Darwin referred to their development as an "abominable mystery." To this day, researchers are still challenged by this "mystery" of how angiosperms originated, rapidly diversified, and rose to dominance. (See the January 2009 issue of the American Journal of Botany at www.amjbot.org/content/vol96/issue1.).

Studies of key features of angiosperm evolution, such as the evolution of the flower and development of the endosperm, have contributed to our current understanding of relationships among the early families of flowering plants. Examining the development of seeds and embryos among early angiosperms may help to improve our understanding of how flowering plants evolved from the nonflowering gymnosperms.

A recent study by Dr. Paula Rudall and his colleagues reported in the recent issue of the AJB (www.amjbot.org/cgi/content/full/96/9/1581) explores a piece of this mystery: the microscopic anatomy of seed development in Trithuria, a genus in the plant family Hydatellaceae, believed to be one of the earliest families of angiospermsthe so-called "basal angiosperms".

Rudall and his colleagues' observations of the development of the embryo and endosperm (tissue that surrounds the embryo and provides nutrition) in Trithuria suggest that double fertilization occurs. Double fertilization is a unique feature of flowering plants where one sperm nucleus unites with the egg, producing the embryo, while another sperm nucleus unites with a separate nucleus from the female, producing the endosperm. The endosperm is divided into two regionsthe micropylar and chalazal regions......... Posted by: Erica      Read more         Source

September 15, 2009, 7:45 AM CT

Conflict between plant and animal hormones

Cis-OPDA (12-oxophytodienoic acid) is a highly reactive plant hormone which simultaneously serves as a precursor molecule of the metabolic "master switch" jasmonic acid. Both signal herbivory in leaves and shoots of plants and activate the plants' defense reaction against caterpillars. Cis-OPDA, when reaching the hemolymph of the caterpillar, has a negative effect on the animal, leading to premature pupation and, apparently, an impaired immune system.

Paulina Dabrowska, one of the very first PhD students of the Jena International Max Planck Research School (IMPRS) who meanwhile earned her PhD, studied the whereabouts of plant hormones after they had been consumed by the caterpillars and had passed the insect gut. Are the hormones, which are known to severely influence development and metabolism of organisms even in the slightest dose, fully metabolized in the insect gut, just converted, or not influenced at all?

Studying the plant hormone cis-OPDA it became quickly evident that a conversion of the molecule must have taken place in the insect gut. The young chemist, originally from Poland, discovered that an enzyme must play a role in the chemical reaction observed: "First, we observed that cis-OPDA was not present in the insect feces anymore. Instead of cis-OPDA, our mass spectrometers suggested iso-OPDA. However, iso-OPDA is only constituted by means of enzyme catalysis." Control experiments, solely performed in strong alkaline solutions as present in the insect gut (pH approx. 10), did not cause a cis-iso conversion. The test animals were Spodoptera littoralis (cotton leaf worm) and Helicoverpa armigera (cotton bollworm) larvae; both species are major cotton pests worldwide......... Posted by: Erica      Read more         Source

September 14, 2009, 11:55 PM CT

For carnivorous plants, slow but steady wins the race

Like the man-eating plant in Little Shop of Horrors, carnivorous plants rely on animal prey for sustenance. Fortunately for humans, carnivorous plants found in nature are not dependent on a diet of human blood but rather are satisfied with the occasional fly or other insect. The existence of carnivorous plants has fascinated botanists and non-botanists alike for centuries and raises the question, "Why are some plants carnivorous?" .

A recent article by Drs. Jim Karagatzides and Aaron Ellison in the recent issue of the American Journal of Botany (www.amjbot.org/cgi/content/full/96/9/1612) addresses this question. As Ellison stated, "The general answer to this is that in environments that have few nutrients (such as bogs, where we study carnivorous plants), carnivory allows these plants to capture nutrients 'on the wing'. But if it's so good to be a carnivorous plant in these kinds of environments, why aren't there more carnivorous plants? Knowing how much it 'costs' a carnivorous plant to make a trap is a key piece of information needed to understand why there aren't more carnivorous plants".

Elllison and Karagatzides simultaneously measured both costs and benefits for traps, leaves, roots, and rhizomes of 15 different carnivorous plant species, including pitcher plants and the Venus fly trap. By measuring the construction cost of carbon needed to create these plant structures and comparing it to the payback timethe amount of time the structure takes to photosynthesize to recoup the carbon used in its constructionEllison and Karagatzides were able to determine how beneficial a trap might be to a plant......... Posted by: Erica      Read more         Source

September 11, 2009, 7:33 AM CT

As ash borer claims more trees

Mark Widrlechner may someday be known as the modern-day Johnny Appleseed for ash trees.

As the devastating insect emerald ash borer is working its way across North America destroying almost all the native ash trees it encounters, Widrlechner is rapidly collecting and storing ash tree seeds.

Like the legendary Appleseed who planted apple trees across the country, Widrlechner's seed stocks can serve as a national source for reintroducing ash trees once the devastation can be controlled.

Widrlechner, horticulturist for the United States Department of Agriculture's Agricultural Research Service (ARS) and assistant professor of agronomy and horticulture at ISU, is a curator at the North Central Regional Plant Introduction Station in Ames, Iowa, responsible for collecting and maintaining seeds for several species of trees, including ash, for the USDA's National Plant Germplasm System.

As the pest devours ash tree populations on its way across North America, there may soon be few, if any, ash trees left.

"Where these borers have been present the longest, it has basically been a total wipeout," said Widrlechner.

"That is something we rarely see in nature," he said. "It's uncommon for a pest to come in and just clean something out. It doesn't just attack sick trees. Emerald ash borer attacks healthy trees. It attacks small trees. So you don't have just big, old trees falling to this, you've got 2 to 3 inch saplings falling to this."........ Posted by: Erica      Read more         Source

September 10, 2009, 7:06 AM CT

Getting plants to rid themselves of pesticide residues

Researchers in China are reporting the "intriguing" discovery that a natural plant hormone, applied to crops, can help plants eliminate residues of certain pesticides. The study is scheduled for the Sept. 23 issue of ACS' Journal of Agricultural and Food Chemistry, a bi-weekly publication.

Jing Quan Yu and his colleagues note that pesticides are essential for sustaining food production for the world's growing population. Farmers worldwide use about 2.5 million tons of pesticides each year. Researchers have been seeking new ways of minimizing pesticide residues that remain in food crops after harvest with little success. Prior research suggested that plant hormones called brassinosteroids (BRs) might be an answer to the problem.

The researchers treated cucumber plants with one type of BR then treated the plants with various pesticides, including chloropyrifos (CPF), a broad-spectrum commercial insecticide. BR significantly reduced their toxicity and residues in the plants, they say. BRs appears to be "promising, environmentally friendly, natural substances suitable for wide application to reduce the risks of human and environmental exposure to pesticides," the researchers note. The substances do not appear to be harmful to people or other animals, they add......... Posted by: Erica      Read more         Source

August 28, 2009, 7:01 AM CT

DNA from Linnaeus' botanical collections

Scientists at Uppsala University has succeeded in extracting long DNA fragments from dried, pressed plant material collected in the 1700s by Linnaeus' apprentice Adam Afzelius. It is hoped that the study, led by Associate Professor Katarina Andreasen, will shed light on whether plants growing today at Linnaeus' Hammarby estate outside Uppsala reflect the species cultivated by Linnaeus himself.

A large number of plants of uncertain provenance grow at Carl Linnaeus' Hammarby estate, a museum and popular tourist destination. Have they been present since Linnaeus' time? In addition to probing this question, the current study will test the limits of DNA-sequencing methods with regard to old plant material and has already demonstrated that it is possible to sequence plant material more than 200 years old. The study is now reported in the scientific journal Taxon

"This opens up many exciting research possibilities in connection with material from herbaria throughout the world", says Katarina Andreasen.

The scientists hopes to initiate corresponding DNA investigations of plant material from the garden at Hammarby as soon as possible.

"It would be fun, if we can show that the old material is genetically identical with the plants currently growing at Hammarby, to create a living herbarium for summer visitors to the garden", says Katarina Andreasen......... Posted by: Erica      Read more         Source