During leaf senescence nutrients are mobilized towards newly developing vegetative and reproductive structures. The IAOx pathway that produces auxin and defense molecules [indole glucosinolates (IGs) and camalexin] is up-regulated during senescence. To investigate the role of the IAOx metabolites we isolated two independent cyp79B2/cyp79B3 double mutants, which are deficient in IGs and camalexin and had reduced auxin levels. Chlorophyll, protein, and gene expression data indicate that cyp79B2/cyp79B3 mutants display early leaf senescence. Furthermore, leaves accumulated higher levels of hydrogen peroxide and seed production was significantly reduced. Auxin signaling at hydathodes and vascular tissue decreased as leaves aged, even though endogenous auxin levels increased. Since CYP79B2/CYP79B3 play only a minor role in auxin synthesis, it is most likely that IGs and/or camalexin are playing a protective role during age-induced developmental leaf senescence. Identifying molecules that slow down the rate of senescence may allow for genetic manipulation to increase nutritional value and crop yield
|Commitee:||Eldon, Elizabeth, Fraser, Deborah|
|School:||California State University, Long Beach|
|School Location:||United States -- California|
|Source:||MAI 55/04M(E), Masters Abstracts International|
|Subjects:||Biology, Molecular biology, Genetics|
|Keywords:||Arabidopsis, Auxin, Indole glucosinolates, Senescence|
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