Project Number: WVA00410
CRIS Number: 0182650
Ethylene Action in Flowers
Investigators: Verlinden, S.
Performing Department: Plant & Soil Sciences -- 1825
Start Date: 10/01/1999
Termination Date: 09/30/2004
Reporting period: 01/01/2001 to 12/31/2001
Progress Report:
The objective of this project is to understand the factors involved in flower senescence and therefore determine flower longevity. Two studies were conducted to gain insight into the processes that underlie flower senescence. First, Petunia corollas were analyzed for changes in ethylene production, fresh and dry weight, carbon content, macronutrient content, and micronutrient content. The corollas lost significant fresh and dry weight and showed a typical ethylene climacteric, observed in other studies. The results of this study indicate that Petunia corollas also loose significant amounts of carbon, nitrogen, phosphorus, and potassium during corolla development and senescence. Carbon content expressed on a gram per corolla basis declined almost as fast as corolla dry weight, suggesting that most carbon loss from the corolla is due to respiration and not the remobilization of carbohydrates. Differences in the patterns of decreasing macronutrients indicate that phosphorus and potassium are lost independently of the ethylene climacteric, while most nitrogen losses occur during the ethylene climacteric. We think that changes in membranes which have been shown to occur before senescence in a number of species may be responsible for the gradual decline in phosphorus while the decline of nitrogen is associated with last stages of development when proteins and nucleic acids are being dismantled. No significant changes in sulfur, calcium, magnesium, and micronutrient content were observed during development. Compared to leaves, corollas have significantly lower concentrations (dry weight basis) of N, P, K, Ca, and Mg. Our results suggest that corollas are a nutritionally inexpensive and therefore, through abscission, easily disposable organ. Our second study was initiated to characterize the effect of sucrose loading on ethylene responsiveness of carnation petals. The results of this study indicate that sucrose loading significantly lowers the ethylene responsiveness of petals. Additional experiments to further characterize this effect showed that sucrose treated petals have lower ACC (ethylene precursor) levels, ACC synthase activity, and ACC synthase mRNA abudance than control petals. Our results suggest that ethylene signal transduction in petals is affected by sucrose loading because of the lower expression of ACC synthase. Interestingly, crosstalk between sucrose and ethylene signaling have been observed in studies in the model plant Arabidopsis. We are currently in the process of cloning CTR1 (the gene at the crossroads between ethylene and sucrose signaling in Arabidopsis) from carnation petals and characterizing the effect of sucrose on its expression and activity.
Publications: (No publications.)
Impact:
Understanding the complex processes associated with flower senescence will lead to novel ways, through genetic engineering or application of chemicals, to increase flower longevity. Increasing flower longevity can lead to an increased economic value of plants (e.g. increased vase life of cut flowers) and/or increased seed and fruit set by extending the time a flower can successfully be pollinated.