July 8, 2010, 6:47 AM CT

Crop development won't satisfy future demand

Eventhough global grain production must double by 2050 to address rising population and demand, new data from the University of Illinois suggests crop yields will suffer unless new approaches to adapt crop plants to climate change are adopted. Improved agronomic traits responsible for the remarkable increases in yield accomplished during the past 50 years have reached their ceiling for some of the world's most important crops.

"Global change is happening so quickly that its impact on agriculture is taking the world by surprise," said Don Ort, U of I professor of crop sciences and USDA/ARS scientist. "Until recently, we haven't understood the urgency of addressing global change in agriculture".

The need for new technologies to conduct global change research on crops in an open-field environment is holding the commercial sector back from studying issues such as maximizing the elevated carbon dioxide advantage or studying the effects of ozone pollution on crops.

However, U of I's Free Air Concentration Enrichment (FACE) research facility, SoyFACE, is allowing scientists to conduct novel studies using this technology capable of creating environments of the future in an open-field setting.

"If you want to study how global change affects crop production, you need to get out of the greenhouse," Ort said. "At SoyFACE, we can grow and study crops in an open-field environment where carbon dioxide and ozone levels can be raised to mimic future atmospheric conditions without disturbing other interactions"......... Posted by: Erica      Read more         Source

July 1, 2010, 7:04 AM CT

Improving Freezing Tolerance in Wheat

New research by UC Davis wheat geneticist Jorge Dubcovsky and colleagues could lead to new strategies for improving freezing tolerance in wheat, which provides more than one-fifth of the calories consumed by people around the world.

The new findings, published June 22 in the Online First issue of the journal Plant Physiology, shed light on the correlation between flowering and freezing tolerance in wheat.

In winter wheat and barley varieties, long exposures to non-freezing cold temperatures accelerate flowering time in a process known as vernalization. These exposures also prepare the wheat to better tolerate freezing, a process known as cold acclimation.

In their newly released study, Dubcovsky and colleagues at UC Davis, The Ohio State University and in Hungary, demonstrated that when the main vernalization gene, VRN1, is expressed in the leaves, it initiates a process that leads to decreased expression of the freezing tolerance genes. (In genetics, "expression" refers to the process by which information carried by the gene is used to create a protein.).

"This system enables wheat and other temperate grasses to respond differently to cool temperatures in the fall than they would to cool temperatures in the spring," said Dubcovsky, a professor in UC Davis' Department of Plant Sciences......... Posted by: Erica      Read more         Source

June 29, 2010, 7:23 AM CT

Longer shelf life for tomatoes

A Purdue University researcher has found a sort of fountain of youth for tomatoes that extends their shelf life by about a week.

Avtar Handa, a professor of horticulture, observed that adding a yeast gene increases production of a compound that slows aging and delays microbial decay in tomatoes. Handa said the results, reported in the early online version of The Plant Journal, likely would transfer to most fruits.

"We can inhibit the aging of plants and extend the shelf life of fruits by an additional week for tomatoes," Handa said. "This is basic fundamental knowledge that can be applied to other fruits".

The organic compound spermidine is a polyamine and is found in all living cells. Polyamines' functions aren't yet fully understood. Handa and Autar Mattoo, a research plant physiologist with the U.S. Department of Agriculture's Agricultural Research Service and collaborator in the research, had shown earlier that polyamines such as spermidine and spermine enhance nutritional and processing quality of tomato fruits.

"At least a few hundred genes are influenced by polyamines, maybe more," Mattoo said. "We see that spermidine is important in reducing aging. It will be interesting to discover what other roles it can have".

Savithri Nambeesan, who was a graduate student in Handa's laboratory, introduced the yeast spermidine synthase gene, which led to increased production of spermidine in the tomatoes. Fully ripe tomatoes from those plants lasted about eight days longer before showing signs of shriveling compared with non-transgenic plants. Decay and rot symptoms linked to fungi were delayed by about three days......... Posted by: Erica      Read more         Source

June 24, 2010, 11:19 PM CT

Plants demonstrate complex ability to integrate information

A University of Alberta research team has discovered that a plant's strategy to capture nutrients in the soil is the result of integration of different types of information.

U of A ecologist J.C. Cahill says the plant's strategy mirrors the daily risk-versus-reward dilemmas that animals experience in their quest for food.

Biologists established long ago that an animal uses information about both the location of a food supply and potential competitors to determine an optimal foraging strategy. Its subsequent behavioral response is based on whether the food supply is rich enough to accept the risks linked to engaging in competition with other animals.

Cahill found plants also have the ability to integrate information about the location of both food and competitors. As a result, plants demonstrate unique behavioural strategies to capture soil resources.

Prior studies show plants alter the growth of their roots in relation to the placement of food or a competing plant. Cahill and colleagues now show an integration of both location and competition information in plants. "This ability to integrate information is a level of complexity never seen in plants before," said Cahill. "This is something we assumed only happened with animals." .

Using a mini-rhizotron camera, referred to by Cahill's team as a "camera on a stick," the scientists compared the root movement of potted plants in relation to various positions of nutrients and competing plants......... Posted by: Erica      Read more         Source

June 24, 2010, 11:11 PM CT

How light receptors get their message across

-For a plant, light is life. It drives everything from photosynthesis to growth and reproduction. Yet the chain of molecular events that enables light signals to control gene activity and ultimately a plant's architecture had remained in the dark. Now a team of scientists from the Salk Institute for Biological Studies and Duke University have identified the courier that gives the signal to revamp the plant's gene expression pattern after photoreceptors have been activated by light.

"Light is probably the most important environmental cue for a plant," says Howard Hughes Medical Institute investigator Joanne Chory, Ph.D., professor and director of the Plant Molecular and Cellular Biology Laboratory and holder of the Howard H. and Maryam R. Newman Chair. "Understanding how light signaling triggers morphological changes in the plant will have a really big impact on every facet of plant biology".

Most animals are able to move away from unfavorable conditions, but plants are sessile and must cope with whatever comes their way. "They have developed an amazing plasticity to deal with varying environmental conditions," says first author Meng Chen, Ph.D., formerly a postdoctoral researcher in the Chory laboratory and now an assistant professor in the Department of Biology at Duke University......... Posted by: Erica      Read more         Source

June 24, 2010, 11:09 PM CT

Genetics in bloom

Some of the molecular machinery that governs flower formation has been uncovered in the daisy-like Gerbera plants. Scientists writing in the open access journal BMC Plant Biology have published a pair of articles detailing how the complex Gerbera inflorescence is formed and how this process differs from other model plants, such as the more simple flowers of Arabidopsis species.

Teemu Teeri, from the University of Helsinki, Finland, worked with a team of scientists to carry out the studies. He said, "Gerbera, a member of the sunflower family, bears compressed inflorescence heads with three different flower types characterized by differences in both sex and floral symmetry. To understand how such a complex inflorescence structure is achieved at the molecular level, we have characterized the array of Gerbera MADS box genes".

The scientists analyzed the expression and evolutionary relationships of six Gerbera genes (GSQUA1-6) that are closely correlation to flower architecture genes in other model species. It seems that this group of genes has expanded in the daisy plant family probably reflecting new functions for these genes in the formation of the complex Gerbera inflorescence. Teeri said, "Our data indicate that none of the GSQUA genes are, by themselves, likely to play a role in defining floral organ identity in the sense of the 'A' function of the floral ABC model. Based on these results, Gerbera can be added to the growing list of plant species that lack the 'A' function comparable to Arabidopsis"......... Posted by: Erica      Read more         Source

June 24, 2010, 10:27 PM CT

Climate change complicates plant diseases

Human-driven changes in the earth's atmospheric composition are likely to alter plant diseases of the future. Scientists predict carbon dioxide will reach levels double those of the preindustrial era by the year 2050, complicating agriculture's need to produce enough food for a rapidly growing population.

University of Illinois scientists are studying the impact of elevated carbon dioxide, elevated ozone and higher atmospheric temperatures on plant diseases that could challenge crops in these changing conditions.

Darin Eastburn, U of I associate professor of crop sciences, reviewed the effects of elevated carbon dioxide and ozone on three economically important soybean diseases under natural field conditions at the soybean-free air-concentrating enrichment (SoyFACE) facility in Urbana.

The diseases downy mildew, Septoria brown spot, and sudden death syndrome were observed from 2005 to 2007 using visual surveys and digital image analysis. While changes in atmospheric composition altered disease expression, the responses of the three pathosystems varied considerably, Eastburn said.

Elevated carbon dioxide levels are more likely to have a direct effect on plant diseases through changes to the plant hosts rather than the plant pathogens.

"Plants growing in a high carbon dioxide environment tend to grow faster and larger, and they have denser canopies," Eastburn said. "These dense plant canopies favor the development of some diseases because the low light levels and reduced air circulation allow higher relative humidity levels to develop, and this promotes the growth and sporulation of a number of plant pathogens"......... Posted by: Erica      Read more         Source

June 24, 2010, 10:16 PM CT

Plant growth hormones

The two most important growth hormones of plants, so far considered antagonists, also work synergistically. The activities of auxin and cytokinin, key molecules for plant growth and the formation of organs, such as leaves and buds, are in fact more closely interwoven than previously assumed. Researchers from Heidelberg, Tbingen (Gera number of) and Umea (Sweden) made this surprising discovery in a series of complex experiments using thale cress (Arabidopsis thaliana), a biological reference organism. The international team of researchers, led by Jan Lohmann, stem cell biologist at Heidelberg University, have now published their results in the scientific journal "Nature". (Nature, 24. Juni 2010).

All the above-ground parts of a plant leaves, buds, stems and seeds ultimately arise from a small tissue at the shoot tip, which contains totipotent stem cells. Since plant stem cells remain active over the entire life of the organism, plants, unlike animals, are able to grow and develop new organs over a number of decades. On the periphery of the tip, auxin triggers cells to leave the pool of stem cells, differentiate and form organs like leaves and buds. Cytokinin stimulates stem cells to divide and proliferate; it maintains the number of cells and thus the plant's growth potential......... Posted by: Erica      Read more         Source

June 21, 2010, 7:12 AM CT

Increasing Potato Production

Despite sophisticated nutrient management of potato crops, quality and yield still see wide variability. Eventhough nutrients are already well understood, the influence of other environmental factors remains understudied.

A research team from Michigan State University conducted a study to determine how the chemical and physical properties of soil, along with the light waves the plant absorbs and reflects, affect potato yield and variability. These findings were integrated with known factors to provide a more complete understand of the influences on potato growth.

Sieglinde Snapp and Alexandra Kravchenko from Michigan State University, and Edgar Po from the University of Missouri reported their findings in the May-June 2010 Agronomy Journal, published by the American Society of Agronomy. Measured across a number of different soil chemical and physical properties, they observed that soil structure was a significant variable that contributed to positive potato yield across coarse-textured commercial field sites.

The study demonstrated the need to supplement monitoring of soil chemical properties, which is a common practice, with data on soil structure and spectral profiles. Soil structure improvement requires dedicated management, but stable soil particle size and their stability in water was a sensitive predictor of field-level variability in potato tuber yield......... Posted by: Erica      Read more         Source

June 9, 2010, 6:49 AM CT

Arsenic hyperaccumulating ferns

Arsenic is toxic to most forms of life, and occurs naturally in soil and ground water in a number of regions of the world. Chronic exposure to arsenic has been associated with lung, bladder and kidney cancer, and thus there are strict limits on allowable levels or arsenic in drinking water. Chemically similar to phosphorus, arsenic forms arsenate (AsO43-), which closely resembles phosphate (PO43-). Arsenate interferes with a number of phosphate-requiring metabolic reactions, including synthesis of adenosine triphosphate (ATP), a ubiquitous and essential source of cellular energy. Thus, exposure to even low levels of arsenic can be extremely toxic.

In well-aerated soils, arsenic exists mainly as arsenate, which is taken up by plant roots using a phosphate transporter protein. Plant tissues rapidly reduce arsenate to arsenite (AsO33-), which is transported to the aerial portions of the plant. In aquatic environments or water-logged soils, arsenic exists primarily as arsenite. Whereas rice grains can accumulate up to 60 µg/g arsenic, the fern Pteris vittata (see figure) can hyperaccumulate arsenic to levels 1000-fold greater than this. A team of scientists led by David Salt and Jo Ann Banks of Purdue University have recently isolated a gene encoding an arsenite transporter protein. This transporter allows these ferns to sequester arsenic in the vacuole, a cellular storage compartment isolated from the cytoplasm by the vacuolar membrane......... Posted by: Erica      Read more         Source