Cloning and Characterization of a cDNA Encoding a Putative Nuclease Related to Petal Senescence in Carnation (Dianthus caryophyllus L.) Flowers

Abstract

Petal wilting, which involves the degradation of cell constituents, such as proteins, polysaccharides, lipids, and nucleic acids, is a determinant of the vase-life of carnation (Dianthus caryophyllus L.) flowers. In this study, a cDNA fragment, encoding a putative nuclease (DcNUC1), was isolated from carnation petals. In the petals of senescing carnation flowers, the level of the DcNUC1 transcript increased, corresponding to the increase of ethylene production. It became maximal in wilted flowers, which suggested the association of DcNUC1 expression with the wilting in carnation flowers.

Flower Senescence-Strategies and Some Associated Events

“…In carnation autocatalytic rise in ethylene has been found to precede the symptoms of senescence and has been found to be associated with increased transcription of genes encoding enzymes involved in ethylene biosynthesis, such as ACC synthase and ACC oxidase (Park et al, 1992). Genes for enzymes that are also upregulated include a glutathione S-transferase, an S-adenosyl methionine synthase, β-glucosidase, β-galactosidase, cysteine proteases, glutamine synthetase, asparagine synthetase, aspartic proteases, nucleases, monodehydroascorbate reductase and phosphate transporter PhPT1 (Meyer et al, 1991;Raghothama et al, 1991;Woodson et al, 1992;Woodson, 1994;Jones et al, 1995;Panavas et al, 1999;Eason et al, 2000;Wagstaff et al, 2002;Jones et al, 2005;Narumi et al, 2006;Xu et al, 2007;Farage-Barhom et al, 2008;Chapin & Jones, 2009;Tripathi et al, 2009;Yamada et al, 2009). The expression of most of these genes has been found to be controlled by the application of exogenous ethylene supporting the view that their upregulation during senescence is regulated by ethylene.…”

“…Most of the changes in gene expression are related to the remobilization of macromolecules and transport of the mobile compounds out of the petal. Degradation of macromolecules in the senescent cell is mainly due to autophagic processes in the vacuole; protein degradation in mitochondria, nuclei, cytoplasm; fatty acid breakdown in peroxisomes and nucleic acid degradation in nuclei (Bieleski, 1995;Mahagamasekera & David, 2001;Wagstaff et al, 2002;Jones et al, 2005;Narumi et al, 2006;Xu et al, 2006;Chapin & Jones, 2007;Hoeberichts et al, 2007;van Doorn & Woltering, 2008;Lerslerwong et al, 2009;Shibuya et al, 2009;Yamada et al, 2009).…”

“…A burst of endogenously produced ethylene in such flowers initiates senescence and coordinates the expression of genes required for the process Kende, 1993;Jones et al, 1995;Jones, 2004;Jones et al, 2005;Narumi et al, 2006;Ichimura et al, 2009;Lerslerwong et al, 2009). The pathway of endogenous ethylene production has been shown to be a developmental consequence or induced by pollination (Whitehead & Halevy, 1989;Ketsa & Rugkong, 2000;Wagstaff et al, 2005;Rogers, 2006;Jones, 2008).…”

“…Activity of PhNUC1 has been found to be induced in non-senescing corollas by treatment with ethylene and was found to delay in ethylene-insensitive mutants (35S: etr1-1) suggesting that regulation of DNA fragmentation and nuclease activity through PhNUC1 is ethylene-dependent. Recently a cDNA fragment, encoding a putative nuclease (DcNUC1) has been isolated from the petals of senescing carnation flowers whose transcripts were also found to be upregulated corresponding to the increase of ethylene production (Narumi et al, 2006).…”