Regulation of Senescence-Related Gene Expression in Carnation Flower Petals by Ethylene

Abstract

Ethylene plays a regulatory role in camation (Dianthus caryophyllus L.) flower senescence. Petal senescence coincides with a burst of ethylene production, is induced prematurely in response to exogenous ethylene, and is delayed by inhibitors of ethylene biosynthesis or action. We have investigated the role of ethylene in the regulation of three senescence-related cDNA clones isolated from a senescent camation petal library (KA Lawton et al. [1989] Plant Physiol 90: 690-696). Expression of two of the cloned mRNAs in response to ethylene is floral specific, while the expression of another mRNA can be induced in both leaves and flowers exposed to ethylene. Although ethylene induces expression of these mRNAs in petals, message abundance decreases when flowers are removed from ethylene unless an autoenhancement of ethylene production is induced. This indicates continued perception of ethylene is required for their expression. Interruption of ethylene action following the onset of natural senescence results in a substantial decrease in transcript abundance of two of these mRNAs. However, the abundance of another mRNA remains unaffected, indicating this gene responds to temporal cues as well as to ethylene. As flowers age the dosage of exogenous ethylene required to induce expression of the cloned mRNAs decreases, indicating sensitivity to ethylene changes as the tissue matures. Nuclear run-on transcription experiments indicate that relative transcription rates of cloned mRNAs increase in response to exogenous ethylene. morphological symptom of senescence. Inhibitors of ethylene biosynthesis or action delay the onset of senescence as well as the associated increase in ethylene biosynthesis. Exposing preclimacteric flowers to exogenous ethylene induces premature petal senescence and an autoenhancement of ethylene production.Flower senescence in carnation is associated with changes in gene expression involving both protein and mRNA changes (29). Some of these changes relate temporally to the onset of increased ethylene biosynthesis and are the result of increased expression of specific senescence-related mRNAs (14). Accumulation of some of these senescence-related mRNAs can be prevented by inhibitors of ethylene biosynthesis or action (14, 30). Given the strict requirement for perception of ethylene in the induction of petal senescence, the role of ethylene in the regulation of senescence-related genes is of interest.To begin to understand the mechanism of ethylene action during flower senescence, we examined the response of three cloned petal senescence-related mRNAs to ethylene. We show that continued perception of ethylene is required for senescence-related gene expression. Furthermore, changes in senescence-related gene expression are related to changes in transcription rate, ethylene concentration, and tissue responsiveness to ethylene. Our results indicate ethylene modulates senescence-related gene expression in carnation petals by a variety of mechanisms. MATERIALS AND METHODSEthylene plays a regulatory ro...

Temporal and Spatial Expression of 1-Aminocyclopropane-1-Carboxylate Oxidase mRNA following Pollination of Immature and Mature Petunia Flowers

“…Total cellular RNA was isolated from frozen tissue as previously described (Lawton et al, 1990), and the concentration was determined by spectrophotometry. Ten-microgram samples of total RNA were separated by electrophoresis through a 1% (w/v) agarose gel containing 2.2 M formaldehyde.…”

Flower senescence: some molecular aspects

“…Genes associated with senescence have been isolated from a number of flowers exhibiting ethylene-sensitive, ethylene-insensitive or intermediate pattern of senescence (Lawton et al 1990;Hunter et al 2002;van Doorn et al 2003;Breeze et al 2004;Hoeberichts et al 2007;Xu et al 2007a). A large population of genes associated with flower senescence have been identified and isolated in Narcissus, Alstroemeria, Iris, Mirabilis, etc.…”

“…The processes of senescence and senescence-induced PCD are regulated by a coordinated signaling pathway, which is consistent with the view that senescence involves PCD (Coupe et al 2004). PCD is an active process that is regulated at both transcriptional and translational levels (Lawton et al 1990;Nooden et al 1997). Literature concerned with the physiology and biochemistry of flower senescence has been updated from time to time by various authors (Stead 1992;van Doorn and Stead 1997;Rubinstein 2000;van Doorn 2001;Zhou et al 2005;eason 2006;Rogers 2006;Tripathi and Tuteja 2007;van Doorn and woltering 2008;Shahri and Tahir 2011).…”

Programmed senescence of plant organs

“…Like leaf senescence, flower organ senescence also serves to remobilize nutrients from the petals to the developing ovary and the process is active, being brought about by changes in gene expression (Lawton et al, 1989(Lawton et al, , 1990Woodson, 1987;Borochov and Woodson, 1989). A number of cDNAs have been isolated from senescing carnation petals which were shown to be regulated by ethylene and correlated with the senescence process (Lawton et al, 1989(Lawton et al, , 1990.…”

“…A number of cDNAs have been isolated from senescing carnation petals which were shown to be regulated by ethylene and correlated with the senescence process (Lawton et al, 1989(Lawton et al, , 1990. Two of the senescence-related cDNAs encode a b-galactosidase (SR12) and a glutathione s-transferase (SR5; Meyer et al, 1991).…”