Progress 09/15/05 to 09/14/08
Outputs
OUTPUTS: Activities: 1. Analysis of all proposed experiment was conducted and finished. Analysis includes: survey of root response to nitrate application, determination of root response mechanism to nitrate presence, transcriptional response of aquaporins to nitrate concentration in rooting medium and whole plant hydraulic effect of nitrate application. Events: Results in their entirety or in pats were presented in two consecutive ASPB meeting (Boston 2007, Merida 2008), as well as AGU (San Francisco 2012), Gordon Conference (Oxford 2009) and German Plant Nutrition Society (Bonn 2012) Service: Three undergraduate students (Harvard University) were participating in the research activity supported by grant. Disseminations: PI participated in several Arnold Arboretum seminars for general audience, discussed the research with K-12 teachers groups. Findings of the research activity were also disseminated at several departmental seminars across USA and Europe including (Cornell University, Ithaca College, University of Chicago, University of Illinois at Chicago, University of Turin, ETH Zurich) PARTICIPANTS: Individuals: Maciej Zwieniecki (Harvard University) - PI N. Michele Holbrook (Harvard University) - Co-Pi Anna Gorska (Harvard University) - Postdoctoral Researcher Q. Ye (Harvard University)- Postdoctoral Researcher J.W Lazor (Harvard University) - undergraduate student internship C. Benway (Harvard University)- undergraduate student internship Collaborators: Vit Glosser - Postdoctoral Researcher (Czech Republic) C.M. Orians - Tufts University Dani Or - ETH Zurich Switzerland TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Change in knowledge We believe that research funded by this award significantly change the prevailing view of the root nitrate uptake strategy from passive search (growth related) to active tracing the nitrate around the soil volume with changes in hydraulic root properties that allow for generation of water flow toward the root in areas reach with nitrate. The research initiated by the project was transformative in respect to better understanding of crop plants response to nitrate fertilizer at cellular and sub-cellular level. Outcome suggests that sensing nitrate concentration in epidermal root cells precedes NR activity and results from nitrate concentration in vacuoles. A change in action: Basic knowledge gained during award duration is now being translated to field activity that have a potential to help design efficient ways of nitrate fertilization (spatial and temporal) specifically designed for species in relation to their root hydraulic activity. Currently new steps are being undertaken to use award findings to determine no-nitrate leaching application technologies for walnut orchards
Publications
- Gorska A., Lazor J.W., Zwieniecka K.A., Benway C., Zwieniecki M.A. 2010. The capacity for nitrate regulation of root hydraulic properties correlates with species nitrate uptake rates. Plant and Soil 337:447-455; DOI: 10.1007/s11104-010-0540-x
- Gorska A., Zwieniecka A., Holbrook N.M., Zwienieck M.A. 2008. Nitrate induction of root hydraulic conductivity in maize is not correlated with aquaporin expression. Planta 228: 989-998
- Gorska A., Ye Q., Holbrook N.M., Zwienieck M.A. 2008. Nitrate control of root hydraulic properties in plants: Translating local information to whole plant response. Plant Physiology 148: 1159-1167
- Gloser V., Zwieniecki M.A., Orians C.M., Holbrook N.M. 2007. Dynamic changes in root hydraulic properties in response to nitrate availability. Journal of Experimental Botany 58: 2409-2415
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Progress 09/15/05 to 09/15/06
Outputs
The major goals of the projects are (1) to understand the biophysical and biological basis for nitrate-induced changes in root hydraulic resistance and (2) to examine the role of this interaction at the whole plant level. We have focused the effort on experiments aiming at testing hypothesis that changes in cytosolic pH induced by the process of assimilation of nitrate lead to gating of aquaporins. First we have established that nitrate induced changes in root hydraulic resistance are very common and occur in all tested plants including: maize, tomato, sunflower, cucumber, poplar and Arabidopsis, although degree of the response and temporal variation is highly variable among the species. Test that involved manipulation of enzyme activity (NR & NiR) and analysis of the resulting changes in root hydraulic resistance suggest that enzymatic pathway is not directly involved in the hydraulic response and that either cytosolic or apoplastic concentration of nitrate forms a
signal for changes in aquaporin activity. These findings are described in a manuscript (currently in review) and were presented at ASPB meeting (Boston 2006). Status of the work: (1) We have selected and hire a postdoctoral fellow to work in the project. (2) Acquired necessary plant material to complete study (3) Established a vigorous connection with NMR center in Czech republic to conduct cytosolic pH changes in roots.
Impacts
The specific information on the influence of the nitrate on root hydraulic resistance will create basis for better practical use of nutrient-water supplements in agricultural practices. The biological bases of the nitrate-water interaction will help and direct future efforts in breeding and crop improvement programs by taking into account higher level of physiological dependences of processes that so far were studied independently.
Publications
- No publications reported this period
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