Ethylene and plant hormones interplay in the regulation of petunia petal senescence

Flower senescence is a fascinating natural process which represents the final development stage of flower life. Plant hormones play an important role in regulating the timing of flower senescence. Ethylene and abscisic acid (ABA) crosstalk affects the flower senescence and usually they accelerate the senescence rate, while the cytokinins are known to delay. The aim of this work was to study the effect of ethylene precursors or inhibitors on petunia petal senescence. Fully open petunia (Petunia × hybrida L. ‘Dreams Appleblossom’) flowers were placed in distilled water (control), 100 µM abscisic acid (ABA), 1 mM 1-aminocyclopropane-1-carboxylic acid (ACC), 2 mM amino-oxyacetic acid (AOA), 500 ppb 1-methylciclopropene (1-MCP), and 200 µM 6-benzylaminopurine (BAP). Ethylene production, ABA, anthocyanins, total carotenoids, and phenols were measured. Results showed that flower longevity was significantly reduced in the treatments with ACC and ABA. The ethylene production was strongly induced in ACC treatment immediately after 24 h and also increased in BAP treatment after 4 days. ABA instead increased in flower treated with ethylene inhibitors such as AOA and 1-MCP. The antioxidant compounds showed slight changes among treatments, but were not significant. In conclusion, data report that ethylene and ABA have an antagonist effect, but both lead to acceleration of petal senescence in petunia.