Progress 04/01/04 to 08/31/12
Outputs
OUTPUTS: For additional information, please contact Jeff Harper at 775-784-1349 or jfharper@unr.edu PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
For additional information, please contact Jeff Harper at 775-784-1349 or jfharper@unr.edu
Publications
- No publications reported this period
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Progress 01/01/11 to 12/31/11
Outputs
OUTPUTS: The long-term goal is understand how calcium signals regulate key events in pollen tube growth and fertilization. The current focus is on defining the role of calcium pumps and ion channels in polarized tip growth. The focus in has been on confirming the results that 1) calcium permeable ion channels, CNGC7, and 8 (cyclic nucleotide gated channels, isoforms 7 and 8) are essential to pollen tube growth, and 2) that CNGC16 is critical for a temperature stress response in pollen. Our results on CNGC16 provide the first genetic identification of a calcium permeable channel involved in a temperature stress response in plants. PARTICIPANTS: Kelly Zinn (post doc), Meral Tunc (post doc), Maryam Ishka (grad-student), Norman Groves (grad-student), Saemin Chang (grad-student), Elizabeth Brown (technician). TARGET AUDIENCES: Target audiences include scientists working on understanding plant systems and the biology underlying reproductive fitness and crop yields under conditions of environmental stress. Efforts include formal classroom instruction, laboratory instruction and publication of research results. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Our results on CNGC16 provide the first genetic identification of a calcium permeable channel involved in a temperature stress response in plants. This suggests that a cyclic nucleotide signal is produced during temperature stresses. We have also obtained evidence that this pathways is critical for a transcriptional response that includes the activation of a heat shock transcription factor.
Publications
- Spalding, E., JF Harper, The ins and outs of cellular Ca transport (2011) Current Opinion in Plant Biology, 14: 715-20. (PMID: 21865080)
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Progress 01/01/10 to 12/31/10
Outputs
OUTPUTS: The long-term goal is understand how calcium signals regulate key events in pollen tube growth and fertilization. The project includes defining the role of calcium pumps and ion channels in polarized tip growth. The focus in the last year has been on confirming the results that 1) calcium permeable ion channels, CNGC7, and 8 (cyclic nucleotide gated channels, isoforms 7 and 8) are essential to pollen tube growth or fertilization (as opposed to pollen grain germination), 2) that the role of CNGC16 to the temperature stress response in pollen includes signaling events that control pollen grain germination, tube growth rate and potential, and tropism toward ovules, 3) that a deregulated ACA (autoinhibited calicum pump) will disrupt calcium signals required for a proper pollen tube stress response. PARTICIPANTS: This project included post-doctoral training for Kelly Zinn and Meral Tunc, and graduate student training for Maryam Ishka TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: none
Impacts
The results on CNGC16 provide the first genetic identification of a calcium permeable channel involved in a temperature stress response in plants...........Preliminary evidence on CNGC7 and 8 indicate that they are endomembrane pumps that are critical to pollen tube tropism or fertilization...........Preliminary evidence on deregulated ACAs indicate that deregulation of an ER located ACA2 will specifically reduce the fitness of pollen under a stress situation (e.g., under conditions of hot days and cold nights, but not normal 22 degree celsius conditions)...........Together, these three outcomes provide novel and fundamental insights into how calcium signals are formed and used for specific purposes in pollen growth and fertilization.
Publications
- Boursiac Y, Lee SM, Romanowsky S, Blank R, Sladek C, Chung WS, Harper JF (2010) Disruption of the vacuolar calcium-ATPases in Arabidopsis results in the activation of a salicylic acid-dependent programmed cell death pathway. Plant Physiol. 154:1158-71.
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: The long-term goal is understand how calcium signals regulate key events in pollen tube growth and fertilization. The project includes defining the role of calcium pumps and ion channels in polarized tip growth. The focus in the last year has been on confirming the results that 1) calcium permeable ion channels, CNGC7, and 8 (cyclic nucleotide gated channels, isoforms 7 and 8) are essential to pollen tube growth, and 2) that CNGC16 is critical for a temperature stress response in pollen PARTICIPANTS: Post Doctorals Kelly Zinn, Meral Tunc, and Yoshimi Barron Undergraduates Richard Hileary and Norman Groves TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
The preliminary results on CNGC16 provide the first genetic identification of a calcium permeable channel involved in a temperature stress response in plants.
Publications
- No publications reported this period
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: The long-term goal is understand how calcium signals regulate key events in pollen tube growth and fertilization. The current focus is on defining the role of calcium pumps and ion channels in polarized tip growth. PARTICIPANTS: This project included post-doctoral training for Yoshimi Barron and Kelly Zinn. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
We have identified 3 calcium permeable ion channels, CNGC18, 7, and 8 (cyclic nucleotide gated channels, isoforms 18, 7 and 8) that are essential to pollen tube growth. A loss of function of CNGC18 alone results in pollen tubes that are kinky and fail to grow towards ovules. A double mutation of isoforms 7 and 8 also results in sterile pollen. Preliminary genetic experiments suggest that a second CNGC channel complex in pollen functions to mediate a temperature stress response. Our research provides the first genetic evidence for an essential function of a CNGC in plants or animals. The preliminary results on a second CNGC complex function in pollen provide the first genetic identification of a calcium permeable channel involved in atemperature stress response in plants.
Publications
- Li X, Chanroj S, Wu Z, Romanowsky SM, Harper JF, Sze H (2008) A Distinct Endosomal Ca2+/Mn2+ Pump Affects Root Growth through the Secretory Process. Plant Physiol. 147: 1675-89
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: The long-term goal is understand how calcium signals regulate key events in pollen tube growth and fertilization. The current focus is on defining the role of calcium pumps and ion channels in polarized tip growth. We have identified 3 calcium permeable ion channels, CNGC18, 7, and 8 (cyclic nucleotide gated channels, isoforms 18, 7 and 8) that are essential to pollen tube growth. A loss of function of CNGC18 alone results in pollen tubes that are kinky and fail to grow towards ovules.
PARTICIPANTS: Post doctoral Sabine Friestch under the supervision of Jeff Harper.
Impacts
Our research provides the first genetic evidence for an essential function of a CNGC in plants or animals. Preliminary evidence indicates that a double mutation of isoforms 7 and 8 also results in male sterility.
Publications
- Frietsch, S, Y-F Wang, C Sladek, LR Poulsen, JI Schroeder, and JF Harper (2007) A Cyclic Nucleotide-Gated Channel essential for polarized tip growth of pollen. PNAS 104: 14531
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Progress 01/01/06 to 12/31/06
Outputs
We have identified several second site suppressor mutations that suppress the partial sterility phenotype of a knockout mutation for calcium pump ACA9. We have begun a long-term strategy to map and clone those suppressor genes. We have expanded our research to investigate the structure and function of a putative calcium permeable ion channel, CNGC18 (cyclic nucleotide gated channel, isoform 18). We have shown that this gene is essential for the life cycle of plants. This provides the first genetic evidence for an essential function of a CNGC in plants or animals. Using an E. coli expression system, we have obtained evidence to support the hypothesis that CNGC18 can function to change calcium transport across the membrane.
Impacts
The research is expected to identify key calcium signaling components necessary for pollen tube growth and fertilization
Publications
- Sze, H, S Frietsch, X Li, KW Bock, JF Harper. (2006) Genomic and molecular analyses of transporters in the male gametophyte. In: Pollen Cell Biology. R Malho, (ed.)
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