Study on the effect of 2, 4 pyridine-dicarboxylate on hormonal regulation of senescence in cut carnation (Dianthus caryophyllus) flowers
2008
Oualid, F.
The senescence of cut carnation flowers (Dianthus caryophyllus) is characterized by the climacteric rise in ethylene production and respiration rate which is accompanied by the up-regulation of ethylene biosynthetic pathway genes. Application of pyridine 2, 4 dicarboxylate (PDCA), an inhibitor of animal prolyl 4 hydroxylases (P4Hs), extended the vase life of carnation flowers through inhibition of ethylene production and climacteric rise in respiration. This inhibition can be attributed to the suppression in transcript abundance of ethylene biosynthetic genes, ACC synthase and ACC oxidase. In addition, preliminary gene expression data using northern blot analysis indicated that PDCA did not affect expression patterns of auxin signaling genes such as a DcAUX/IAA. In addition to cut carnation flowers, we used individual petals as a model system to complement and confirm our experimental data. The major advantage of this system is the potential to use petals of identical developmental age when are excised from the same flower. Short-term treatment of petals with PDCA resulted in complete suppression of ACC oxidase only and not of ACC synthase, indicating that the primary target of PDCA is the transcription of ACC oxidase. In addition, a polyclonal antibody was raised against DcP4H1 and tested in total proteins extracts from petal and leaf tissue of carnation and Arabidopsis using Western blot analysis. Conclusively, our data suggest involvement of proline hydroxylation in ethylene biosynthesis and particularly in transcriptional activation of ACC oxidase in senescence of several flower organs such as petals and ovaries.
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