May 12, 2008, 9:37 PM CT

Beyond nutrition: plants deliver

The need for a renewable and affordable source of carbon that can sustain future economic development without negatively impacting the environment is now widely recognised. It is also apparent that the increasingly high demand for fossil carbon will eventually deplete existing stocks.

The Plant Journal is pleased to present a series of invited peer-reviewed articles that describe processes that plants can or could use to convert their fixed carbon into fuels and other useful products. The articles were commissioned to provide an authoritative scientific backdrop to inform discussion in debates on finding alternative and reliable sources of carbon.

Co-edited by Christoph Benning from Michigan State University and Eran Pichersky from the University of Michigan, this special issue is freely available to download online here: http://www.blackwell-synergy.com/toc/tpj/54/4.

The 17 articles in this special issue cover topics related to the production of biofuel from plant or algal biomass. In addition, several articles highlight the usefulness of plant s for the production of pharmaceutical drugs and other high value chemicals and polymers. A flavour of the scope of articles is given below.

Smith reports on how increases in yield of starch and sugars could lead to a sustainable production of bioethanol as a liquid transport fuel......... Posted by: Erica      Read more         Source

Fri, 09 May 2008 02:11:08 GMT

Fritillaria affinis

Thanks once again to Jackie Chambers of UBC Botanical Garden for submitting a photograph and write-up!

Fritillaria affinis has just begun flowering in the Garry Oak Meadow at the UBC Botanical Garden. The meadow is part of a recent initiative to expand the garden''s native plant collections. To learn more about this unique and threatened landscape in British Columbia, visit the site of the Garry Oak Ecosystems Recovery Team.

Native to western North America, Fritillaria affinis populations can be found in southern British Columbia through to California. Common English names include checker lily, chocolate lily, or mission bells.

Flowers can be single or in clusters of 3-5 and are produced in the spring (April-May). They can range from 1-4cm long, and are often purple as a base colour, then checkered with greenish-yellow dots. In fact, the genus name is based on this checkered pattern: Fritillaria is derived from the Latin fritillus, which means "dice box".

Flower shape and colour can vary significantly depending on location (e.g., see the Pacific Bulb Society Wiki on North American Fritillaria). All flowers are hermaphroditic, though, meaning they have both staminate (pollen-producing) and carpellate (ovule-producing) structures.

This perennial plant can range in height from 10 to 130cm. The leaves can range from 3-15 cm long, and are often arranged in whorls of 3-5 leaves along the stem. Plants emerge from a bulb typically surrounded by smaller bulblets (link to commercial site).

The USDA NRCS has an extensive factsheet about Fritillaria affinis (PDF), including details about the traditional harvest and cultivated management of these bulbs by the Coast and Interior Salish First Nations. Posted by: Daniel Mosquin      Read more     Source

Fri, 09 May 2008 00:57:35 GMT

Transgenic SunUp Papaya Genome

This week's issue of Nature features the draft genome of the transgenic 'SunUp' Papaya, the first commercial virus-resistant transgenic fruit tree to be sequenced. From Nature News: The papaya genome will be of interest to scientists interested in the dietary benefits of different fruits, the evolution of fruiting trees, and other basic questions of biology. Data from the genome will also help in designing field-based assays to differentiate hermaphroditic plants from female ones - a task that currently takes farmers three to four months of cultivation to achieve. Farmers prefer the hermaphroditic plants for easier pollination. In addition to insights regarding its evolutionary path, the genome analysis also revealed that papaya has fewer functional genes than any other flowering plant already sequenced, but contains more genes for enzymes involved in cell-wall expansion, starch production and for production of volatile compounds.

Read more from the University of Illinois report. Posted by: ruth      Read more     Source

May 7, 2008, 7:46 PM CT

Gardeners get advice from neighbors, friends

Where do gardeners turn when they need information about annuals, perennials, shrubs and trees" Staff at University of Minnesota Extension have published results of a survey that concludes that the majority of backyard gardeners get their planting and plant information informallymost often from friends, neighbors and local garden centers.

The survey of 1,000 Minnesota gardeners reported in the JanuaryMarch, 2008 issue of HortTechnology showed that eventhough respondents viewed the The University of Minnesota and the Minnesota Landscape Arboretum as more credible than garden centers, 78% of respondents indicated that they were most likely to turn to neighbors and friends for gardening advice.

Dr. Mary Hockenberry Meyer, Professor of Horticultural Science and Extension Horticulturist at UM Extension, explained, "We wanted to determine where gardeners got their information and if they think university information is of higher quality than information from garden centers or home centers. We observed that university information is viewed as higher quality; however, a large number of people indicated they "did not know" the quality of university information, which surprised us".

The survey also indicated that gardeners' age determined the most likely sources for information seeking. Older gardeners were less likely to use the Internet than younger gardeners. When asked "How do you learn best"", most respondents said that they had not attended a gardening class in the past year and indicated they learn best from talking with friends. Access to publications containing color photos and illustrations was also highly valued by gardeners who responded to the survey......... Posted by: Erica      Read more         Source

May 7, 2008, 7:44 PM CT

Silicon's effect on sunflowers

Vibrant, showy sunflowers are revered worldwide for their beauty and versatility. While a number of varieties of sunflower are grown specifically for their nutritional benefits, ornamental sunflowers have become standards for commercial growers and everyday gardeners. As sunflowers' popularity grows, researchers are looking for new supplements and growing methods to enhance production and quality of this celebrated annual.

Horticulturists have found ample evidence that plants depend on "essential nutrients"; naturally occurring elements that are found in normal plant tissue that are essential for the completion of the life cycle of the plant. Eventhough silicon, a predominant element in mineral soil, is not considered to be an essential nutrient for most plants, there has been limited evidence that silicon supplements affect the aesthetic qualities of ornamental flowers and crops.

Drs. Sophia Kamenidou and Todd J. Cavins, formerly of the Department of Horticulture and Landscape Architecture at Oklahoma State University, published a research study in the February, 2008 issue of HortScience in which they examine the effects of silicon supplements on sunflowers grown in greenhouse environments.

"In greenhouse production, most floricultural crops are cultivated in soilless substrates, which often supply limited amounts of plant-available silicon. The goal of this study was to determine the effects of silicon supplementation on greenhouse-produced ornamental sunflower (Helianthus annuus L. Ring of Fire).", explained Cavins. "This is one of the first studies to highlight supplemental silicon impact on horticultural traits. Most prior research on silicon has focused on disease suppression in hydroponic vegetable production. This is also one of the few examples of detrimental effects seen from high silicon concentrations"......... Posted by: Erica      Read more         Source

May 5, 2008, 9:09 PM CT

Ecologists tease out private lives of plants and their pollinators

The quality of pollen a plant produces is closely tied to its sexual habits, ecologists have discovered. As well as helping explain the evolution of such intimate relationships between plants and pollinators, the study one of the first of its kind and published online in the British Ecological Society's journal Functional Ecology also helps explain the recent dramatic decline in certain bumblebee species found in the shrinking areas of species-rich chalk grasslands and hay meadows across Northern Europe.

Relationships between plants and pollinators have fascinated ecologists since Darwin's day. While ecologists have long known that pollinators such as honeybees and bumblebees are often faithful to certain flowers, and have done much work on the role of nectar as a food source, very little is known about how pollen quality affects these relationships.

Working on Salisbury Plain, the largest area of unimproved chalk grassland in north west Europe, ecologists from the universities of Plymouth, Stirling and Poitiers in France collected pollen from 23 different flowering plant species, 13 of which are only pollinated by insects while the other 10 species can either pollinate themselves or be insect pollinated. They analysed the pollen for protein content and, in the second part of the study, recorded bumblebee foraging behaviour......... Posted by: Erica      Read more         Source

April 30, 2008, 5:24 PM CT

Patent Office rejects company's claim for bean

The United States Patent and Trademark Office (USPTO) today rejected all of the patent claims for a common yellow bean that has been a familiar staple in Latin American diets for more than a century.

The bean was erroneously granted patent protection in 1999, as US Patent Number 5,894,079, in a move that raised profound concerns about biopiracy and the potential abuse of intellectual property (IP) claims on plant materials that originate in the developing world and remain as important dietary staples, especially among the poor.

A research center, the International Center for Tropical Agriculture (known by its Spanish acronym, CIAT), which is supported by the Consultative Group on International Agricultural Research (CGIAR), led the legal challenge to the patent through the USPTOs reexamination process.

We are happy that the patent office has reached a final decision in this case but remain concerned that the ex partes patent reexamination procedure meant that these patent claims remained in force for such a long time, said Geoffrey Hawtin, Director General of CIAT, which has been fighting the patent since 2001. For several years now, farmers in Mexico, the USA and elsewhere have unnecessarily endured legal threats and intimidation for simply planting, selling or exporting a bean that they have been growing for generations......... Posted by: Erica      Read more         Source

April 21, 2008, 7:38 PM CT

RNA Role In Spreading Disease

Recent research that links specific pieces of RNA to an infectious organism's duplication and spread could lead the way to the prevention of viroids, pathogens that can kill or damage food crops and other plants.

The findings and the research approach used by Ohio State University researchers also could have applications in the study of how certain viruses spread in humans because the pathogens have some similar characteristics.

The scientists have developed an experimental system to identify specific structural parts of a viroid that are responsible for its multiplication and spread of the disease.

Because no chemical therapys exist that can specifically inhibit viroid infection, an effective way to prevent viroid multiplication and spread is through genetic alterations of susceptible plants. The best approach to such bioengineering is learning exactly how the pathogens function in the first place, said Biao Ding, senior author of the study and professor of plant cellular and molecular biology at Ohio State.

"We're trying to understand how the infection occurs, and how the RNA propagates itself in the cell. But more importantly, even for human diseases, is discovering how a disease spreads. That's where the problem comes in the plant," Ding said......... Posted by: Erica      Read more         Source

April 17, 2008, 4:03 AM CT

Sudden Oak Death pathogen is evolving

The pathogen responsible for Sudden Oak Death first got its grip in California's forests outside a nursery in Santa Cruz and at Mt. Tamalpais in Marin County before spreading out to eventually kill millions of oaks and tanoaks along the Pacific Coast, as per a new study led by scientists at the University of California, Berkeley. It provides, for the first time, evidence of how the epidemic unfolded in this state.

"In this paper, we actually reconstruct the Sudden Oak Death epidemic," said Matteo Garbelotto, UC Berkeley associate extension specialist and adjunct professor, and principal investigator of the study. "We point to where the disease was introduced in the wild and where it spread from those introduction points".

The study, scheduled to appear later this month in the online early edition of the journal Molecular Ecology, also shows that the pathogen is currently evolving in California, with mutant genotypes appearing as new areas are infested. These findings suggest that movement of infected plants between different regions where Sudden Oak Death is established should be minimized, said Garbelotto.

Garbelotto will present these findings today (Wednesday, April 16) at the annual meeting of the California Oak Mortality Task Force, a coalition of research institutions, public agencies, non-profit organizations and private industry formed to coordinate management, research, outreach and policy efforts surrounding Sudden Oak Death disease in California. Garbelotto is a member of the task force......... Posted by: Erica      Read more         Source

April 10, 2008, 9:16 PM CT

Flowers' fragrance diminished by air pollution

Air pollution from power plants and automobiles is destroying the fragrance of flowers and thereby inhibiting the ability of pollinating insects to follow scent trails to their source, a new University of Virginia study indicates. This could partially explain why wild populations of some pollinators, especially bees which need nectar for food are declining in several areas of the world, including California and the Netherlands.

The study appears online in the journal Atmospheric Environment.

"The scent molecules produced by flowers in a less polluted environment, such as in the 1800s, could travel for roughly 1,000 to 1,200 meters; but in today's polluted environment downwind of major cites, they may travel only 200 to 300 meters," said Jose D. Fuentes, a professor of environmental sciences at the University of Virginia and a co-author of the study. "This makes it increasingly difficult for pollinators to locate the flowers".

The result, potentially, is a vicious cycle where pollinators struggle to find enough food to sustain their populations, and populations of flowering plants, in turn, do not get pollinated sufficiently to proliferate and diversify.

Other studies, as well as the actual experience of farmers, have shown that populations of bees, especially bumblebees, and butterflies have declined greatly in recent years. Fuentes and his team of U.Va. researchers, including Quinn McFrederick and James Kathilankal, think that air pollution, particularly during the peak period of summer, may be a factor......... Posted by: Erica      Read more         Source

April 9, 2008, 8:47 PM CT

Novel 'gene toggles' in world's top food crop

University of Delaware researchers, in collaboration with U.S. and international colleagues, have found a new type of molecule--a kind of "micro-switch"--that can turn off genes in rice, which is the primary source of food for more than half the world's population. The discovery is published in the March 25 issue of the Proceedings of the National Academy of Sciences of the United States of America.

Composed of short lengths of ribonucleic acids (RNAs), on the order of about 20 nucleotides long, these novel molecules, called natural antisense microRNAs (nat-miRNAs), target the genes sitting directly across from them on the opposite strand of DNA in a rice cell.

In addition to uncovering a new genetic switch and gaining insight about its pathways and evolution, which are important to the health of a grain that feeds most of the world, the research also may help researchers locate this type of novel gene regulator in other organisms, including humans. MicroRNAs regulate 30 percent of human genes and thus are critical to human health and development.

The research was led by Pamela Green, the Crawford Greenewalt Chair of Plant Sciences at UD, and Blake Meyers, associate professor of plant and soil sciences, and their laboratory groups at the Delaware Biotechnology Institute, including associate scientist Cheng Lu, postdoctoral scientists Dong-Hoon Jeong and Kan Nobuta, graduate students Karthik Kulkarni, Manoj Pillay, and Shawn Thatcher and research associate Rana German......... Posted by: Erica      Read more         Source

Thu, 10 Apr 2008 02:22:56 GMT

Variegated leaf porn

Whenever I put the word “porn” on my blog I get lots of hits. I need all the help I can get, so as a sort of follow-up to my post on the science behind variegated leaves, here’s some variegated leaf porn from Roger Williams Park Botanical Conservancy in Providence.

I have no idea what any of these plants are. Any ideas anyone? Jo-Ann B., if you’re out there chime in because I know you know the answer! I think it’s the coolest thing ever that the leaves are variegated green/cream on the top side, but all purple on the bottom side. Very wacky things going on with pigments and genes here.

Below is an example of a plant that lacks chlorophyll (green pigment). It has instead an excess of the anthocyanin, the pigment that produces reds, pinks, and purples. Posted by: Caroline Brown      Read more     Source

Mon, 07 Apr 2008 00:59:50 GMT

Trachystemon orientalis

Thank you to UBC Botanical Garden horticulturist Jackie Chambers for today''s photographs and write-up, much appreciated!

A fine example of Trachystemon orientalis can be found in the David C. Lam Asian Garden here at UBC. The coarse-textured, heart-shaped leaves are bright green and reach 25-30cm long. However, it is the dainty blue flowers, currently in bloom, that are the most striking feature of this perennial groundcover.

The flowers are held on hairy, purple flower stalks of 15-30cm in height. Flower stalks emerge in early spring (March-April) before the leaves have reached full size. Individual flowers are about 1cm in diameter, and are hermaphroditic - meaning they have both staminate (pollen producing) and carpellate (ovule producing) structures (additional photographs). Stiff hairs and blue flowers are typical features of members of Boraginaceae.

Trachystemon is derived from the Greek trachys, meaning rough, and stemon, a stamen. The species name orientalis means eastern or from the orient, and is a reference to the native distribution of this species. Trachystemon orientalis is endemic to southeastern Europe and western Asia.

In Turkey, the plant is eaten as a vegetable, and has the common name aci hodan. The flowers, stems, young leaves and rhizome may all be cooked and eaten (see the entry on Trachystemon orientalis on Plants for a Future database).

English common names include Abraham-Isaac-Jacob, and Eastern or Oriental borage. Despite being native to Bulgaria, Turkey, and Georgia, Trachystemon orientalis has naturalized throughout the UK. It was first introduced as an ornamental, but records indicate established escapee populations in some areas of England date back to 1868. Here''s a more recent distribution map of Trachystemon orientalis populations in the UK.

From a horticulturist perspective, this plant is an extremely useful groundcover; while it prefers partly shaded woodland locations, it can tolerate full sun to shade, and a range of soil conditions. It even performs well in dry shade which is always a challenge for gardeners. Posted by: Daniel Mosquin      Read more     Source

April 3, 2008, 8:32 PM CT

Genes key to hormone production in plants

Scientists at North Carolina State University have pinpointed a small group of genes responsible for telling plants when, where and how to produce a hormone that is key to their development. Their findings shed light on the ways in which hormone production in plants affects both a plants growth and its ability to adapt to changing environments.

Dr. Jose Alonso, assistant professor of genetics, and a team of geneticists and plant biologists from NC State, Gera number of and the Czech Republic conducted the research. Their findings appear in the April 4 edition of the journal Cell.

Plant growth and development are regulated by a small number of hormones, which plants combine in various ways so that they can adapt to and thrive in changing environmental conditions. Auxin and ethylene are two of the most important of these growth-regulating hormones.

Researchers had previously established that plants respond differently to ethylene depending upon the type of plant tissue it is applied to, the developmental stage of the plant, and the surrounding environmental conditions. They also knew that the presence of auxin, another key growth-regulator, often served as a trigger for a plant to produce more ethylene, but were unsure of the ways in which auxin was synthesized......... Posted by: Erica      Read more         Source

April 2, 2008, 10:19 PM CT

Will Avocados be Next?

Researchers with the USDA Forest Service Southern Research Station (SRS), Iowa State University, and the Florida Division of Forestry have provided the first description of a fungus responsible for the wilt of redbay trees along the coasts of South Carolina, Georgia, and Florida.

In the recent issue of Plant Disease, SRS plant pathologist Stephen Fraedrich and fellow scientists provide results from their assessment of the fungus, the beetle that carries it, and their combined effect on redbay and other members of the laurel family, including sassafras, spicebush, and avocado.

Extensive mortality of redbay, an attractive evergreen tree common along the coasts of the southeastern United States, has been observed in South Carolina and Georgia since 2003. Though the wilt was at first attributed to drought, the cause was soon found to be a fungal pathogen and the exotic redbay ambrosia beetle, Xyleborus glabratus, a native to Southeast Asia that was first found in the area in 2002. A number of ambrosia beetles carry species of fungi as food for their larvae; a previously undescribed fungus in the genus Raffaelea is a fungal symbiont of this ambrosia beetle.

To determine if the fungus was the cause of the wilt, Fraedrich and colleagues inoculated redbay trees and containerized seedlings with the Raffaelea fungus; the plants died within 5 to 12 weeks. To connect fungus and beetle, they also exposed redbay seedlings to X. glabratus beetles; the ambrosia beetles tunneled into almost all of the plants, causing 70 percent of them to die. The scientists found the fungus in 91 percent of the beetle-attacked plants......... Posted by: Erica      Read more         Source

March 31, 2008, 9:13 PM CT

Pathway plants use to fight back against pathogens

Plants are not only smart, but they also wage a good fight, as per a University of Missouri biochemist. Prior studies have shown that plants can sense attacks by pathogens and activate their defenses. However, it has not been known what happens between the pathogen attacks and the defense activation, until now. A new MU study revealed a very complex process that explains how plants counter attack pathogens. This discovery could potentially lead to crops with enhanced disease resistance.

There is a chemical warfare between plants and pathogens, said Shuqun Zhang, associate professor of biochemistry in the College of Agriculture, Food and Natural Resources and the College of Medicine. Normally, plants put effort into growth and development. However, when plants sense pathogens, they have to use some of their energy and resources to make secondary metabolites to fight disease. Until now, very little has been known about how this process is regulated.

As per the study, plants first sense the attack of a pathogen, and then activate defense responses by triggering a complex signaling cascade in plants. One of the defense responses is the induction and accumulation of anti-microbial defense chemicals, known as phytoalexins.

In his study, Zhang found the specific signaling path, known as a mitogen-activated protein kinase (MAPK) cascade, in the plants that ends when the defense chemical camalexin is created. Camalexin is essential for resistance to some plant diseases. Zhang used Arabidopsis, a small flowering plant and the first to have its entire genome sequenced, and Botrytis cinera, a fungal pathogen that causes grey mold disease in many plants including grapes and strawberries......... Posted by: Erica      Read more         Source

Mon, 31 Mar 2008 00:08:48 GMT

Cnidoscolus stimulosus

Todays Botany Photo of the Day comes courtesy of Bruce Vanderveen aka duneaster@Flickr (original via UBCBG BPotD pool). Check out his collection of native plant photos from Florida.

Who could suspect this dainty member of the Euphorbiaceae of being such a menace? A flower has never looked so appetizing, bearing such close resemblance to a piece of floral confectionary from some wedding cake. However, with such suggestive common names as finger rot and tread softly, it''s no surprise that this plant isn''t found on cakes or in bouquets. As can be seen from today''s image, Cnidoscolus stimulosus is covered in trichomes. In the case of Cnidoscolus stimulosus, these small hairs will irritate the skin upon contact. Regarding tread softly and other plants which possess such weaponry, Nancy C. Coile writes,

"The urticating hair or trichome has a bulbous and very fragile tip which breaks off at an angle and results in a perfect tool for piercing skin. Basically, the shaft of the hair resembles a glass tube due to the deposition of silica in the cell wall during formation (Thurston 1974). When the urticating hair tip is broken, it has the action of a hypodermic needle and injects the urticating substances which cause the intense pain and result in irritated skin rashes." (from Florida''s Department of Agriculture - Urtica chamaedryoides Pursh: a Stinging Nettle, or Fireweed and Some Related Species - PDF).

Cnidoscolus stimulosus is often mistaken for the true stinging nettle, Urtica dioica. The latter has a near world-wide distribution while finger-rot is confined to the southeastern United States. As far as the urticating substances in Cnidoscolus stimulosus are concerned, I can only guess that they might include those found in Urtica dioica such as histamine, acetylcholine, and serotonin (from the previously mentioned article). Posted by: Daniel Mosquin      Read more     Source

March 27, 2008, 9:21 PM CT

Can you rescue a rainforest?

Half a century after most of Costa Rica's rainforests were cut down, scientists from the Boyce Thompson Institute took on a project that a number of thought was impossible - restoring a tropical rainforest ecosystem.

When the scientists planted worn-out cattle fields in Costa Rica with a sampling of local trees, native species began to move in and flourish, raising the hope that destroyed rainforests can one day be replaced.

Carl Leopold and his partners in the Tropical Forestry Initiative began planting trees on worn-out pasture land in Costa Rica in 1992. For 50 years the soil was compacted under countless hooves, and its nutrients washed away. When it rained, Leopold says, red soil appeared to bleed from the hillsides.

The group chose local rainforest trees, collecting seeds from native trees in the community. "You can't buy seeds," Leopold says. "So we passed the word around among the neighbors." When a farmer would notice a tree producing seeds, Leopold and his wife would ride out on horses to find the tree before hungry monkeys beat them to it.

The group planted mixtures of local species, trimming away the pasture grasses until the trees could take care of themselves. This was the opposite of what commercial companies have done for decades, planting entire fields of a single type of tree to harvest for wood or paper pulp......... Posted by: Erica      Read more         Source

March 24, 2008, 8:25 PM CT

Corn's roots dig deeper into South America

Corn has long been known as the primary food crop in prehistoric North and Central America. Now it appears it may have been an important part of the South American diet for much longer than previously thought, as per new research by University of Calgary archaeologists who are cobbling together the ancient history of plant domestication in the New World.

In a paper reported in the March 24 advanced online edition of the Proceedings of the National Academy of Sciences (PNAS), U of C PhD student Sonia Zarrillo and archaeology professor Dr. Scott Raymond report that a new technique for examining ancient cooking pots has produced the earliest directly dated examples of domesticated corn (maize) being consumed on the South American continent. Their discovery shows the spread of maize out of Mexico more than 9,000 years ago occurred much faster than previously believed and provides evidence that corn was likely a vital food crop for villages in tropical Ecuador at least 5,000 years ago.

The domestication and dispersal of maize has been a hot topic in archaeology for decades and these are the earliest indisputable dates for its presence in South America, Raymond said. It has long been thought that maize may have been used south of Panama at this time for ritual purposes but this shows it was also being consumed as food......... Posted by: Erica      Read more         Source

Wed, 19 Mar 2008 01:54:27 GMT

Arabidopsis thaliana

Today''s entry, organized by Connor Fitzpatrick, is the fourth in a BPotD series for UBC Research Week. The photographs and write up come courtesy of Dr. Fred Sack, Professor and Head, Department of Botany.

Each leaf contains thousands of pores, stomata, which allow gas exchange between the atmosphere and the shoot. Stomata are cellular valves central to plant survival because they allow carbon dioxide to enter leaves where it is used to make sugars in photosynthesis. Stomata are also adaptive because they close down when water loss becomes too great. Efficient gas exchange seems to require that valves be spaced apart from each other since it is rare in nature to find two stomata in direct contact.

My lab pioneered the discovery of genes required for stomatal formation and spacing. We first determined how stomata develop and are distributed in the model eudicot Arabidopsis. As in all plants, stomatal formation requires an initial division that is unequal in size and fate, generating a smaller cell and a larger cell. After the smaller cell becomes oval in profile, it divides equally thus producing the two young guard cells that develop into the stoma. Meanwhile the larger cell produced by the unequal division can in turn divide asymmetrically. Normally this "piggyback" (iterative) division is oriented so that the new small precursor cell does not contact the previously formed one, a placement that generates the minimal one-celled separation between stomata. This placement probably requires intercellular communication, a conclusion reinforced when we identified the TOO MANY MOUTHS gene which encodes a probable receptor. Defects in TMM induce spacing violations, suggesting that it normally receives spatial cues used to correctly orient "piggyback" divisions. TOO MANY MOUTHS acts exclusively in the cells that form stomata as shown by the distribution of green fluorescent protein in the accompanying picture (red shows the cell walls; note that stomata are still forming in this picture; reproduced from Nadeau and Sack, Science). Thus this gene, which is conserved in monocots as well, controls the division behavior of islands of stem cells distributed throughout the epidermis of the developing shoot.

We also found that a different gene, FOUR LIPS, is required to ensure that there is only one equal division of the GMC (the guard mother cell is a precursor to guard cells). Mutations in FLP induce extra, abnormal, equal divisions resulting in four guard cells (lips) in a row ("stoma" comes from the Greek for "mouth"). We found that FLP is a transcription factor that regulates genes involved in cell cycling. Additional genes in this pathway are being identified in collaboration with Erich Grotewold at Ohio State University. It is likely that restricting GMC divisions to one (failsafe) would be strongly selected for in evolution since the control of water loss and the efficiency of carbon dioxide uptake are critical for plant survival.

The first photograph was taken using cryoscanning electron microscopy. The second photograph was taken using confocal laser scanning microscopy. The red channel shows the cell outlines (cell walls labeled with propidium iodide), and the green channel shows where the gene TMM is expressed. Posted by: Daniel Mosquin      Read more     Source

March 16, 2008, 9:48 PM CT

Nutrient regulation of biological clock in plants

Using a systems biological analysis of genome-scale data from the model plant Arabidopsis, an international team of scientists identified that the master gene controlling the biological clock is sensitive to nutrient status. The study will appear in the latest issue of the Proceedings of the National Academy of Sciences. This hypothesis derived from multi-network analysis of Arabidopsis genomic data, and validated experimentally, has shed light on how nutrients affect the molecular networks controlling plant growth and development in response to nutrient sensing.

The study was conducted by a team of scientists at New York Universitys Center for Genomics and Systems Biology, Chiles Pontificia Universidad Catlica de Chile, Dartmouth College, and Cold Spring Harbor Labs. The studys lead authors are Rodrigo A. Gutirrez of the Pontificia Universidad Catlica de Chile and Gloria Coruzzi of NYUs Center for Genomics and Systems Biology. They note that the systems biology approach to uncovering nutrient regulated gene networks provides new targets for engineering traits in plants of agronomic interest such as increased nitrogen use efficiency, which could lead to reduced fertilizer cost and lowering ground water contamination by nitrates.

Researchers have previously studied how nitrogen nutrients affect gene expression as a way to understand the mechanisms that control plant growth and development. Nitrogen is an essential nutrient and a metabolic signal that is sensed and converted, resulting in the control of gene expression in plants. In addition, nitrate has been shown to serve as a signal for the control of gene expression in Arabidopsis, the first flowering plant to have its entire genome sequenced. There is current evidence, on a gene-by-gene basis, that products of nitrogen assimilation, the amino acids glutamate (Glu) or glutamine (Gln), might serve as signals of organic nitrogen status that are sensed and in turn regulate gene expression......... Posted by: Erica      Read more         Source

Thu, 13 Mar 2008 02:58:13 GMT

Lotus japonicus and Lotus berthelotii

Connor''s been gathering entries for a new series on BPotD, and it starts today. Connor writes:

Research Week has officially begun at UBC. This year''s Research Week is particularly special as it marks UBC''s 100th anniversary. Events are taking place from March 4-15 that celebrate the research conducted by all of UBC''s faculties, departments, schools and partner institutions.

From March 4 to March 15, Botany Photo of the Day will feature research from the Department of Botany, the Faculty of Forestry and the Faculty of Land and Food Systems.

Dr. Quentin Cronk, a professor in the Faculty of Land and Food Systems and Director of the UBC Botanical Garden and Centre for Plant Research, shares with us today his research on the evolution of bird pollination:

These two photographs show two species of the legume genus Lotus. The yellow flower is Lotus japonicus, a "model organism" for legume biology. Its genome is being sequenced to aid the study of legume biology, particularly nodulation, the process by which legumes partner with nitrogen-fixing bacteria to produce their own fertilizer (a major source of nitrogen in the best agricultural systems). In order to separate the genetic components of nodulation, many mutants have been raised. You can see a fanciful animation of how these mutants are created and screened by the "magical mutation machine". Lotus japonicus, as the name implies, comes from Japan, but there are a number of closely related species throughout temperate Eurasia, including the familiar Lotus corniculatus ("bacon and eggs") which is widely introduced in North America (and can be seen all over the UBC campus).

The red flower is a narrow Canary Island endemic called Lotus berthelotii, sometimes grown in warmer gardens under the name "parrot vine". It makes a low, mounded, trailing bush with grey leaves. It looks so different from Lotus japonicus because it is bird-pollinated (Lotus japonicus, like most Lotus species, is bee pollinated).

The flowers are shown side-by-side to illustrate the different pollination mechanisms (for convenience the larger Lotus berthelotii flowers are shown the same size as the Lotus jaonicus flower). Bees are attracted to the flat upright "standard" petal of the yellow flower and land on the closed wing and keel petals, which they have to open to get at the pollen. In consequence the flowers are held horizontally. In Lotus berthelotii, ground perching birds probe down into the flowers from above and therefore the flowers are held in an upright position. Bird pollinated flowers are often red, both to attract birds and to help bird flowers avoid the attentions of bees. For animals like birds, with good colour vision, red contrasts well with green foliage. However, it is camouflaged from bees, as insect eyes are insensitive to the red end of the spectrum.

Together with graduate student Isidro Ojeda, my laboratory is investigating the evolution of bird pollination in Lotus and the gene expression changes that are associated with the very different flower type. The project fits well with our interest both in the evolution and biology of island plants and also in flower development. We are collaborating with the Jardín botanico canario Viera y Clavijo in Gran Canaria and with Arnoldo Santos Guerra of the Jardín de aclimatacion de La Orotava in Tenerife.

Incidentally, one mystery we have not yet solved is how we can persuade Lotus berthelotii to flower reliably in western Canada. Whether under glass or outside it remains stubbornly vegetative. We have tried hormone treatments, light treatments, various temperature regimes, not to mention various fertilizer treatments, and yet we only get the occasional flower here in Vancouver. In the Canary Islands, the plants are covered with flowers in April and May. Posted by: Daniel Mosquin      Read more     Source

March 11, 2008, 10:38 PM CT

New twist on life's power source

A startling discovery by researchers at the Carnegie Institution puts a new twist on photosynthesis, arguably the most important biological process on Earth. Photosynthesis by plants, algae, and some bacteria supports nearly all living things by producing food from sunlight, and in the process these organisms release oxygen and absorb carbon dioxide. But two studies by Arthur Grossman and his colleagues*+ reported in Biochimica et Biophysica Acta and Limnology and Oceanography suggest that certain marine microorganisms have evolved a way to break the rulesthey get a significant proportion of their energy without a net release of oxygen or uptake of carbon dioxide. This discovery impacts not only researchers basic understanding of photosynthesis, but importantly, it may also impact how microorganisms in the oceans affect rising levels of atmospheric carbon dioxide.

Grossmans team investigated photosynthesis in a marine Synechococcus, a form of photosynthetic bacteria called cyanobacteria (formerly blue-green algae). These single-celled organisms dominate phytoplankton populations over much of the worlds oceans and are important contributors to global primary productivity. Grossman and colleagues wanted to understand how Synechococcus could thrive in the iron-poor waters that cover large areas of the ocean, since certain activities of normal photosynthesis require high levels of iron. While others had suggested a potential role of oxygen as accepting electrons from the photosynthetic apparatus in place of carbon dioxide, the studies by Grossmans group show that this activity is significant in the oligotrophic (nutrient-poor) oceans, which cover about half the oceans area......... Posted by: Erica      Read more         Source