The dynamics between nitrogen, specifically NO3 and CO2 are discussed.
From
Stitt M. 1999. Nitrate regulation of metabolism and growth.
Curr Opin Plant Biol. Jun;2(3):178-86.
Recent research shows that signals derived from nitrate are involved in triggering widespread changes in gene expression, resulting in a reprogramming of nitrogen and carbon metabolism to facilitate the uptake and assimilation of nitrate, and to initiate accompanying changes in carbon metabolism. These nitrate-derived signals interact with signals generated further downstream in nitrogen metabolism, and in carbon metabolism. Signals derived from internal and external nitrate also adjust root growth and architecture to the physiological state of the plant, and the distribution of nitrate in the environment.
Coruzzi GM, Zhou L. 2001 Carbon and nitrogen sensing and signaling in plants: emerging 'matrix effects'. Curr Opin Plant Biol. 2001 Jun;4(3):247-53
Plants, like other organisms, have developed mechanisms that allow them to sense and respond to changes in levels of carbon and nitrogen metabolites. These mechanisms, in turn, regulate the expression of genes and the activities of proteins involved in C and N transport and metabolism, allowing plants to optimize the use of energy resources. Recent studies, which have involved molecular-genetic, genomic, and cell biological approaches, have begun to uncover the signals and components of C:N sensing and signaling mechanisms in plants. For sugar sensing, analysis of Arabidopsis mutants has revealed intersections with hormone and nitrogen signaling. For nitrogen sensing/signaling, recent progress has identified transcriptional and posttranslational mechanisms of regulation. In all, a complex picture is emerging in which C:N signaling systems are subject to a 'matrix effect' in which downstream responses are dependent upon cell-type, developmental, metabolic, and/or environmental conditions.
This is full pdf paper, worth a read.
http://www.plantphysiol.org/cgi/reprint/125/1/61.pdf
Another full paper that discusses some Carbon PO4 and Nitrogen feedback and control. Plant cells must have some sort of regulation to incorporate C, N and P together to operate efficiently.
Carbon metabolite feedback regulation of leaf photosynthesis and development -- Paul and Pellny 54 (382): 539 -- Journal of Experimental Botany
My point here is not to have you all understand everything contained in these papers. It is to realize that the CO2 can affect the N metabolism and vice versus, limiting NO3 can and does reduce the capacity of the plant to use CO2, the enzymes required for CO2 uptake are large and require a lot of N.
Likewise, for the plant to use N effectively, it needs the carbon skeletons/sugars etc to work with to link the Nitrogen together.
P is really important and limiting that will shut down and slow most all growth a great deal, when added back, the plant will rapidly start growing again.
You can see these effects on the whole plant level also, not just with gene expression using mRNA, or protein upregulation etc.
That level is voodoo to many folks, but it's clear what is going on to the plant scientyists to some degree, but many questions still remain.
What is clear, that these are not independent units, they all have feedback loops.
So the take home message here:
Maintain good non limiting stable nutrient levels and make sure to use the CO2 correctly.
If you reduce the levels too much too often, you can run into trouble and the recovery process can take several days.
Regards,
Tom Barr
From
Stitt M. 1999. Nitrate regulation of metabolism and growth.
Curr Opin Plant Biol. Jun;2(3):178-86.
Recent research shows that signals derived from nitrate are involved in triggering widespread changes in gene expression, resulting in a reprogramming of nitrogen and carbon metabolism to facilitate the uptake and assimilation of nitrate, and to initiate accompanying changes in carbon metabolism. These nitrate-derived signals interact with signals generated further downstream in nitrogen metabolism, and in carbon metabolism. Signals derived from internal and external nitrate also adjust root growth and architecture to the physiological state of the plant, and the distribution of nitrate in the environment.
Coruzzi GM, Zhou L. 2001 Carbon and nitrogen sensing and signaling in plants: emerging 'matrix effects'. Curr Opin Plant Biol. 2001 Jun;4(3):247-53
Plants, like other organisms, have developed mechanisms that allow them to sense and respond to changes in levels of carbon and nitrogen metabolites. These mechanisms, in turn, regulate the expression of genes and the activities of proteins involved in C and N transport and metabolism, allowing plants to optimize the use of energy resources. Recent studies, which have involved molecular-genetic, genomic, and cell biological approaches, have begun to uncover the signals and components of C:N sensing and signaling mechanisms in plants. For sugar sensing, analysis of Arabidopsis mutants has revealed intersections with hormone and nitrogen signaling. For nitrogen sensing/signaling, recent progress has identified transcriptional and posttranslational mechanisms of regulation. In all, a complex picture is emerging in which C:N signaling systems are subject to a 'matrix effect' in which downstream responses are dependent upon cell-type, developmental, metabolic, and/or environmental conditions.
This is full pdf paper, worth a read.
http://www.plantphysiol.org/cgi/reprint/125/1/61.pdf
Another full paper that discusses some Carbon PO4 and Nitrogen feedback and control. Plant cells must have some sort of regulation to incorporate C, N and P together to operate efficiently.
Carbon metabolite feedback regulation of leaf photosynthesis and development -- Paul and Pellny 54 (382): 539 -- Journal of Experimental Botany
My point here is not to have you all understand everything contained in these papers. It is to realize that the CO2 can affect the N metabolism and vice versus, limiting NO3 can and does reduce the capacity of the plant to use CO2, the enzymes required for CO2 uptake are large and require a lot of N.
Likewise, for the plant to use N effectively, it needs the carbon skeletons/sugars etc to work with to link the Nitrogen together.
P is really important and limiting that will shut down and slow most all growth a great deal, when added back, the plant will rapidly start growing again.
You can see these effects on the whole plant level also, not just with gene expression using mRNA, or protein upregulation etc.
That level is voodoo to many folks, but it's clear what is going on to the plant scientyists to some degree, but many questions still remain.
What is clear, that these are not independent units, they all have feedback loops.
So the take home message here:
Maintain good non limiting stable nutrient levels and make sure to use the CO2 correctly.
If you reduce the levels too much too often, you can run into trouble and the recovery process can take several days.
Regards,
Tom Barr
