Back to the main page

Archives Of Plant Science Blog

Subscribe To Plant Science Blog RSS Feed  RSS content feed What is RSS feed?

October 2, 2007, 9:49 PM CT

How 'Mother of Thousands' Makes Plantlets

How 'Mother of Thousands' Makes Plantlets
The houseplant "mother of thousands" makes the tiny plantlets that drop from the edges of its leaves. (Neelima Sinha/UC Davis photo)
New research shows how the houseplant "mother of thousands" (Kalanchoe diagremontiana) makes the tiny plantlets that drop from the edges of its leaves. Having lost the ability to make viable seeds, the plant has shifted some of the processes that make seeds to the leaves, said Neelima Sinha, professor of plant biology at UC Davis.

A number of plants reproduce by throwing out long shoots or runners that can grow into new plants. But mother of thousands goes further: the plantlets are complete miniature plants that become disconnected from the mother plant's circulatory system and drop off, allowing them to spread rapidly and effectively. The houseplant has lost the ability to make viable seeds and only reproduces through plantlets.

Helena Garcês, a graduate student in Sinha's laboratory, Sinha and his colleagues looked at two genes, STM and LEC, in mother of thousands and close relatives, some of which make seeds instead of plantlets. STM controls shoot growth, while LEC is involved in making seeds.

Expression of STM in leaves was essential for making plantlets. In most plants LEC is expressed in seeds, but mother of thousands' version of the gene, LEC1, was expressed in leaves as well. When the scientists transferred the LEC1 variant into other plants, they were unable to make viable seeds.........

Posted by: Erica      Read more         Source

October 1, 2007, 10:08 PM CT

Amazon Forest Unexpectedly Resilient to Drought

Amazon Forest Unexpectedly Resilient to Drought
During the 2005 drought in the Amazon, intact primary forest showed an increase in photosynthetic activity (left image) despite below-average rainfall (right image). Data from NASA's Terra satellite (left) showed areas of higher (green) and lower (red) growth during the peak of the drought (July-Sept.). Data from the Tropical Rainfall Measuring Mission satellite (right) showed areas of severe rainfall reduction due to the drought (red) and few areas with above normal rainfall (blue). Credit: Kamel Didan, University of Arizona Terrestrial Biophysics and Remote Sensing Lab.
The extensive forests of South America's Amazon are turning out to be tougher than expected when it comes to withstanding the onslaughts of a changing climate. A team of U.S. and Brazilian scientists using the insightful eyes of two NASA satellites has shown that one of the worst droughts in decades could not stop the undisturbed regions of the Amazon forest from "greening up".

The Amazon drought of 2005 reached its peak just as the region's annual dry season was beginning, from July through September. Although the double whammy of the parched conditions might be expected to slow the growth of the forest's leafy canopy, in much of the drought-stricken areas the canopy became significantly greener -- an indication of increased photosynthetic activity.

"Instead of 'hunkering down' during a drought as you might expect, the forest responded positively to drought, at least in the short term," said study author Scott R. Saleska, an assistant professor of ecology and evolutionary biology at the University Of Arizona. "It's a very interesting and surprising response".

The new finding contradicts a prominent global climate model that predicts the Amazon forest would begin to "brown down" after just a month of drought. The model also predicts an eventual forest collapse, shifting the ecosystem permanently from a thick, evergreen, broad-leaved forest to a grassy savanna.........

Posted by: Erica      Read more         Source

October 1, 2007, 9:54 PM CT

Genetic differences in clover make one type toxic

Genetic differences in clover make one type toxic
That clover necklace you make for your child could well be a ring of poison.

Thats because some clovers have evolved genes that help the plant produce cyanide to protect itself against little herbivores, such as snails, slugs and voles, that eat clover. Other clover plants that do not make cyanide are found in climates with colder temperatures. So, in picking your poison, er, clover, ecology and geography play important roles.

A plant evolutionary biologist at Washington University in St. Louis is trying to get to the bottom of this botanical cloak and dagger tale. Kenneth Olsen, Ph.D., Washington University assistant professor of biology in Arts & Sciences, is looking at the genetics of a wide variety of white clover plants to determine why some plants do and some plants dont make cyanide what biologists call polymorphism, or two types.

We are documenting the effect of natural selection at the DNA sequence level to understand the molecular evolution of this polymorphism, said Olsen. Usually, scientists study model plants such as Arabidopsis or tobacco to understand genetics. But with clover we have a system where we can look in detail at DNA sequence variation and at the same time have a thorough understanding of the plants ecology.

As per a research findings published the week of Sept. 24 in the journal Molecular Ecology, Olsen and colleagues report findings on the molecular basis of the cyanide polymorphism.........

Posted by: Erica      Read more         Source

Tue, 02 Oct 2007 03:39:30 GMT

Cercidiphyllum japonicum

Cercidiphyllum japonicum
Thank you again to Douglas Justice for both today's photograph and accompanying written entry. – Daniel.

This year the katsuras are colouring well. Cercidiphyllum japonicum is not well known for autumn finery in Vancouver, I suppose because our typical dry summer weather usually causes much early leaf drop. Either that, or when plants are shaded, the rich green colour slowly drains out of the leaves until they're an insipid, anonymous straw-yellow. However, when the fates conspire and the colours emerge, katsuras are like fireballs: all saturated red, pink, orange and blackening maroon, like a simmering furnace of molten metals and slag.

My father planted a katsura at home along the back fence when I was a few years old. As far as I can remember it was always there, and I can only recall a few times when we had the kind of brilliant display we're witnessing this year. But regardless of the depth of its autumn tints, I always considered the species impressive. I love its rough, ascending trunks and perfect, rounded leaves with their regimented, two-by-two placement along its wire-like branches. I love the exuberance of its growth, opportunistically sprouting new shoots everywhere when conditions are ideal (katsuras prefer cool temperatures and revel in summer moisture). I even love the tiny ephemeral flowers; these are arranged along the mature leafless branches in spring and look like little rubies when the light catches them sideways.

Most of all, however, I love the smell of the senescing leaves. For some reason, as the leaves of Cercidiphyllum start to break down, they become intensely aromatic. Some say the aroma is like candy-floss or strawberries. Lately, the distinctive burnt sugar fragrance suggests crème brûlée to me (perhaps I'm not getting enough expensive desserts to eat). To be honest, it really reminds me of raking katsura leaves in my childhood, an activity I eagerly anticipated and never saw as a chore — which goes to show that my dad is smarter than I thought.

Posted by: Daniel Mosquin      Read more     Source

September 26, 2007, 8:17 PM CT

Emphasizing the 'precision' in precision agriculture

Emphasizing the 'precision' in precision agriculture
New protocols are making it easier for growers to use previously ineffectual soil and environmental data to better manage their crops.

Credit: James Taylor
New protocol and software developments are helping farmers put the precision back in precision agriculture by making it easier for growers to use previously ineffectual soil and environmental data to manage their crops.

Historically, gaps between scientists and producers, as well as lack of capacity to transform data into relevant decisions, have all contributed to data languishing on hard drives rather than being used to inform growing decisions.

Using software available online, scientists from the Australian Centre for Precision Agriculture (ACPA) at the University of Sydney have developed a simplified protocol to teach growers how to convert complex yield and soil data into pertinent information. The resulting data and maps, when interpreted with local agronomic knowledge, can be used to make class-specific management decisions.

The protocol provides [growers] with the ability to experiment on their fields with different combinations of temporal data layers to improve their understanding of how their fields respond, said James Taylor and his team of scientists who worked with a range of growers to develop the methodology.

The scientists article in the September/October 2007 Agronomy Journal details their work in advancing field management, in particular their efforts to move away from treating all zones uniformly to more site-specific management. After receiving protocol training on how to analyze and apply field data, Australian growers were able to utilize the protocol and software to develop better field management, including implementing site-specific nutrient and pest management therapys.........

Posted by: Erica      Read more         Source

September 26, 2007, 7:46 PM CT

How and why people respond differently to drugs

How and why people respond differently to drugs
Crystal structure for UGT (UDP-glycosyltransferase) in a plant related to Arabidopsis thaliana.

Credit: Cutler lab, UC Riverside.
While prescription medications work successfully to cure an ailment in some people, in others the same dose of the same drug can cause an adverse reaction or no response at all.

As per a research team led by Sean Cutler, an assistant professor of plant cell biology at UC Riverside, such variation in drug responses can be analyzed by studying much simpler organisms like plants.

The genetics behind variable drug responses is not peculiar to humans but exists also in other branches on the tree of life, Cutler said. We can harness simple organisms to understand more about the genetics and biochemistry of variable drug responses, which could help uncover new factors that contribute to variable drug responses in humans.

Study results appear in the Sept. 23 online publication of Nature Chemical Biology

Focusing on Arabidopsis thaliana, a weedy plant in the mustard family, Cutlers lab discovered a key protein in the plant that creates drug resistance. Called UGT (UDP-glycosyltransferase), the protein is a member of a family of proteins that also affect drug sensitivity in humans.

Similar biochemical processes are affecting drug sensitivity in both plants and animals, said Cutler, who joined UCRs Department of Botany and Plant Sciences and the Center for Plant Cell Biology in January 2007. These similarities suggest that plants can be useful for studying problems of human interest like drug responses.........

Posted by: Erica      Read more         Source

September 25, 2007, 9:47 PM CT

Spatial patterns in tropical forests

Spatial patterns in tropical forests
Canopy of lowland hill dipterocarp forest in Sinharaja taken from the top of a lowland hill - Sinhagala (about 800m asl). It shows different species in different stages of leaf flushing (light green) and early fruiting (pinkish - red) stages but none in the picture in bloom.

Credit: Nimal Gunatilleke
The high biodiversity in tropical forests has both fascinated and puzzled ecologists for more than half a century. In the hopes of finding an answer to this puzzle, ecologists have turned their attention to the spatial patterns of such communities and mapped the location of each tree with a stem larger than a pencil in plots covering 25 to 52ha of tropical forest around the world. As per a research findings published in The American Naturalist a German - Sri Lankan research team has now undertaken thousands of spatial pattern analyses to paint an overall picture of the association between tree species in one of these plots in Sri Lanka.

"The problem of studying spatial association between species is that habitat association confounds the effect of plant-plant interactions" says Dr Wiegand, senior scientist at the Helmholtz Centre for Environmental Research in Leipzig, Gera number of. The breakthrough in their analysis is that it allowed them to disentangle these two effects and to look in a new way at their data. "From prior studies we knew that growth and survival of trees depends quite strongly on their neighbors" say Savitri Gunatilleke and her husband Nimal, both professors at the University of Peradeniya, "we had therefore expected to find strong signatures of positive or negative interactions between species in our data". "However, the fact that not more than 5 percent of the 2070 species pairs we have analyzed showed significant associations is quite remarkable." A conclusion of their study is that neighborhood-dependent processes may equilibrate, thereby producing neutral association patterns in the spatial distribution of trees. "This is certainly not the last word in this debate," says Wiegand "but it is a step towards an understanding of the complexities of the origin and maintenance of species richness in tropical forests".........

Posted by: Erica      Read more         Source

September 23, 2007, 11:21 AM CT

Amazon forest shows unexpected resiliency

Amazon forest shows unexpected resiliency
Drought-stricken regions of the Amazon forest grew especially vigorously during the 2005 drought, as per new research.

The counterintuitive finding contradicts a prominent global climate model that predicts the Amazon forest would begin to "brown down" after just a month of drought and eventually collapse as the drought progressed.

Instead of hunkering down during a drought as you might expect, the forest responded positively to drought, at least in the short term," said study author Scott R. Saleska of The University of Arizona. "It's a very interesting and surprising response."

UA co-author Kamel Didan added, "The forest showed signs of being more productive. That's the big news".

The 2005 drought reached its peak at the start of the Amazon's annual dry season, from July through September. Eventhough the double whammy of the parched conditions might be expected to slow growth of the forest's leafy canopy, for a number of of the areas hit by drought, the canopy of the undisturbed forest became significantly greener -- indicating increased photosynthetic activity.

Saleska, a UA assistant professor of ecology and evolutionary biology, and colleagues at the UA and at the University of So Paulo in Brazil used data from two NASA satellites to figure out that undisturbed Amazon forest flourished as rainfall levels plummeted.........

Posted by: Erica      Read more         Source

Wed, 19 Sep 2007 04:36:29 GMT

Tower Hill Botanical Garden

Tower Hill Botanical Garden
Last week I drove up to Tower Hill Botanical Garden in Boylston, Mass., about an hour’s drive from Providence. Tower Hill is the home of the Worcester County Horticultural Society (that’s Wussta to all you non-New Englanders), a non-profit organization that is the third oldest horticultural society in the U.S.

I took the above photo from just outside the visitors center. The lake near the center of the pic is Wachusett Reservoir, a public drinking water supply. To the right is another view of the reservoir from near the Tower Hill Summit (a whopping 641 1/2 feet though it looks like it’s a lot higher doesn’t it?) I don’t know what the mountain in the background is called, but there is a place in Mass. called Mt. Wachusett so that’d be my guess.

It really was so beautiful up there, very fall-like and windy. Although the leaves haven’t really turned yet, all the plants and trees look pretty tired and you can tell the time has come. It reminded me of of an area that I’m pretty familiar with near Asheville in the NC mountains.

Lots of cool trails and gardens with art and architecture incorporated–pavilions, pergolas, a “temple of peace” and an urn that once belonged to Alexander Pope. My favorite was the Orangerie, a 18th-century style greenhouse that was recently built “to provide the lush environment of an endless summer during the long, dormant winter months” of New England. Below is a pic of the Orangerie taken from Tower Hill’s website:

Tower Hill has several “themed” gardens and natural areas as expected; one of my favorites was the Wildlife Refuge Pond. Here are a couple of different views.

Lots of the usual suspects–cattail, rush, sedge, ferns, shadbush, blueberry, winterberry, inkberry. In full bloom were Joe-pye weed, goldenrod, and the ubiquitous New England aster.

Below is a pic of asters with rosehips–I think it was Virginia rose?

More photos from some of the other gardens in a future post.

Posted by: Caroline Brown      Read more     Source

Tue, 18 Sep 2007 12:53:53 GMT

Mycena interrupta

Mycena interrupta
Botany Photo of the Day will have brief written entries on weekends, holidays and my vacations from April through September. – Daniel

Ken Beath, aka kjbeath@Flickr is the person to thank for today's photograph (original via the BPotD Flickr Group Pool). Do visit Ken's Australia photo galleries if you've the time! Thanks, Ken.

Measuring approximately 1cm across, pixie's parasol is a diminutive mushroom of fallen wood substrates in moist forests of Australia, New Zealand and Chile. The Royal Botanic Gardens Melbourne had a fungus of the month site for two and a half years, and Mycena interrupta was featured. Special mention was made of the Gondwanan distribution pattern.

Posted by: Daniel Mosquin      Read more     Source


Older Blog Entries