Leaf senescence is the final stage of leaf development that is characterized by highly regulated genetic programs. This process involves recycling and recovery of the nutrients and relocating them to the developing part of the plant for high yield of fruits and grains. In this project we focused on four genes (WRKY45, NAC084, NAC100 and undesignated NAC) that coded for either WRKY or NAC transcription factors to determine their effects on leaf senescence by assaying both chlorophyll and protein levels, analyzing chlorophyll and protein degradation rates and quantifying the transcript abundance of senescence marker genes, WRKY75, NIT2, DGR2 and Lhcb2. wrky45 mutants showed early senescence. We observed lower chlorophyll level and faster chlorophyll degradation rate that was supported by the real time qPCR data showing greater upregulation in SURG and downregulation in SDRG. These findings suggest that WRKY45 gene has a negative regulatory effect in WT plants. In contrast, nac084 mutant showed delayed senescence. We found higher chlorophyll level and slower chlorophyll degradation rate that was supported by the real time qPCR data showing downregulation of SURG and upregulation of SDRG. These findings suggest a positive regulatory effect of NAC084 in senescence. NAC100 did not show any significant changes in leaf senescence. On the other hand, undesignated NAC behaved like a normal gene as the und-nac-1 mutant was not affected by a T-DNA insertion and may not have disrupted gene expression.
|Commitee:||Eldon, Elizabeth, Fisher, Amanda|
|School:||California State University, Long Beach|
|Department:||Chemistry and Biochemistry|
|School Location:||United States -- California|
|Source:||MAI 57/01M(E), Masters Abstracts International|
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