Generation of stomata

**"* C* M* <j*@earthlink.net>**

Dear GWL members,

I thought this might be if interest.

John C. MacGregor IV
Horticultural Consultant
Garden Design and Maintenance
Writer, Photographer, Lecturer

jonivy@earthlink.net
(626) 799-1554
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>> --------------------------------------------------------------------- 
>> ------------
>> "To help determine the number of stomata a newly sprouting leaf  
>> should form, the plant takes key factors
>> about its surrounding climate—carbon dioxide levels, temperature  
>> and humidity—into account."
>> --------------------------------------------------------------------- 
>> -------------------------------------------------------------------
>>
>> Stanford University <http://www.stanford.edu/>
>> Stanford News Service <http://news-service.stanford.edu/>
>>
>> Stanford Report, November 24, 2008
>>
>>
>>   Stanford researchers investigate how plants adapt to climate
>>
>> BY KAYVON SHARGHI
>>
>> How many mouths does a plant need in order to survive? The answer  
>> changes depending on climate, and some of the decisions are made  
>> long before a new leaf sprouts.
>>
>> Stanford researchers have found that the formation of microscopic  
>> pores called stomata (derived from the Greek word stoma, meaning  
>> mouth) is controlled by a specific signaling pathway that blocks  
>> activity of a single protein required for stomata development. The  
>> findings are described in a paper published Nov. 14 in /Science/.
>>
>> Stomata are found on almost every terrestrial plant on Earth.  
>> Their multiple roles include releasing moisture and oxygen into  
>> the environment, providing internal air conditioning for the plant  
>> and allowing carbon dioxide to enter the leaf, where it is  
>> converted to sugar during photosynthesis. Stomata are essential  
>> for the survival of plants and, by absorbing carbon from the  
>> atmosphere, play a significant role in maintaining the health of  
>> the planet.
>>
>> Using /Arabidopsis thaliana/, a fast-growing, flowering plant used  
>> for genetic and developmental studies, Dominique Bergmann, an  
>> assistant professor of biology, and paper co-authors Gregory  
>> Lampard, a postdoctoral fellow, and Cora MacAlister, a PhD  
>> student, found a unique structural region on a protein with 10  
>> sites that can be modified by a well-known, environmentally- 
>> controlled signaling pathway to dictate the number of stomata a  
>> plant makes.
>>
>> "Scientists have said that the environment affects plant  
>> development, but no one could point to a protein that was  
>> responsible for that response," Bergmann said. "Now we know a  
>> major target inside the cell and how it is regulated."
>>
>> Knowing how this process works could be used to modify crops in  
>> order to maximize their productivity under changing climate  
>> conditions. Plants might initially benefit as a result of the  
>> increased carbon supply in the atmosphere due to global warming,  
>> Bergmann said, but would also respond to those conditions by  
>> making fewer stomata. The result? Loss of cooling through stomata  
>> could lead to widespread crop failures due to the rise in  
>> temperatures associated with global warming.
>>
>> "There are circumstances where you might want to disconnect the  
>> signals plants receive from the environment so they can survive,"  
>> Bergmann said.
>>
>> The protein, which the researchers dubbed SPEECHLESS, initiates  
>> the first of a three-step cell division process that leads to the  
>> formation of stomata in plants. Though structurally similar to  
>> SPEECHLESS, two other proteins involved in subsequent steps do not  
>> contain the same control region that is regulated by the signaling  
>> pathway. This provides a unique mechanism for the signaling  
>> pathway to control SPEECHLESS activity in a set of stem-cell-like  
>> cells and hence the ultimate development of stomata.
>>
>> "If I were designing the leaf, that would be the part I would put  
>> under really tight control," Bergmann said. "It seems as if that's  
>> what plants have done."
>>
>> Certain trade-offs exist for plants having too many or too few  
>> stomata. To help determine the number of stomata a newly sprouting  
>> leaf should form, the plant takes key factors about its  
>> surrounding climate—carbon dioxide levels, temperature and humidity 
>> —into account.
>>
>> To perceive these factors, the plant uses the same signaling  
>> pathway used to control SPEECHLESS activity. The study identifies  
>> a critical junction that connects how a plant can sense  
>> environmental conditions with how this information is relayed to  
>> stomatal-development pathways. Thus, development of stomata can be  
>> altered "on the fly" to better enable the plant to cope with  
>> environmental conditions.
>>
>> For example, a leaf contains fewer pores when carbon dioxide in  
>> the atmosphere is in abundance and more when it is limited. If  
>> conditions change, this multi-faceted signaling system can enable  
>> fine-tuning of stomatal development.
>>
>> The research was funded by grants from the National Science  
>> Foundation, U.S. Department of Energy, a Terman Award from  
>> Stanford University, and the Stanford Genome Training Program.
>>
>> /Kayvon Shargi is a science-writing intern at the Stanford News  
>> Service. /
>>
>> SR
>>
>>
>>     Related Information
>>
>>     * /Science/ paper
>>       <http://www.sciencemag.org/cgi/content/full/322/5904/1113>
>>
>> --------------------------------------------------------------------- 
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>>
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>> (650) 723-2300.
>>
>> --------------------------------------------------------------------- 
>> ---
>> <http://news-service.stanford.edu/news/2008/december3/ 
>> stomata-120308.html?view=print#>
>> <http://news-service.stanford.edu/news/2008/december3/ 
>> stomata-120308.html?view=print#>
>>
>>
>> -- 
>> =====================================
>> "The greatest disturbances of which we are aware are those now  
>> being introduced by man himself. Since his tampering
>> with the biological and geochemical balances may ultimately prove  
>> injurious -- even fatal -- to himself, he must understand
>> them better than today."
>>
>> Bert Bolin. "The Carbon Cycle." Scientific American, September 1970
>> ===================================================
>> "The individual scientist can survive for a long time by lying low  
>> in the valley of specialized intellectual interest ... We in science
>> must get up and face the wind, confront the future."
>> William Bevan, "The Sound of the Wind That's Blowing." American  
>> Psychologist. July 1976
>> =================================================================
>>
>>
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