Abstract
This study investigated whether ethylene is involved in the stem-bending mechanism of three different snapdragon cultivars ‘Asrit Red’, ‘Asrit Yellow’, and ‘Merryred Pink’, by treating their cut stems with an ethylene-releasing compound (ethephon), an ethylene-action inhibitor [silver thiosulfate (STS)], and distilled water (as the control). Ethephon completely prevented stem bending in all cultivars, whereas STS exhibited a higher bending rate compared with the control. The bending rates were influenced by several factors, such as the degree of stem curvature, relative shoot elongation, ethylene production, and lignin content, indicating their involvement in the stem-bending mechanism of the cultivars. The analysis of the expression of genes involved in the ethylene and lignin biosynthetic pathways also supported the importance of lignin and ethylene in the stem-bending mechanism. Taken together, as ethephon completely prevented stem bending of the three snapdragon cultivars, this study suggested that ethylene acts as a negative regulator of the stem-bending mechanism of snapdragon cultivars, and the information will be valuable for the prevention of stem bending in other commercially important ornamental flowers.
Highlights
The vase life of cut snapdragon flowers (Antirrhinum majus L.) is usually determined by the stem-bending rate, rather than petal senescence, because they cannot be used for commercial purpose once their stems are bent
Varying degrees of stem curvature in response to the treatments were observed in all cultivars at 3 days after treatment (DAT), with the degree of stem curvature observed for the silver thiosulfate (STS) treatment being significantly higher than that of the control, and that observed in the ethephon-treated stems being the lowest of the three conditions (STS > control > ethephon)
Despite a slight variation in stem curvature among the cultivars in response to the treatments, ethephon significantly inhibited the induction of stem curvature in all cultivars, whereas STS strongly induced stem curvature, with the curvature induced by the STS treatment being significantly greater than that afforded by the control treatment in all cultivars at 3, 6, and 9 DAT, respectively
Summary
The vase life of cut snapdragon flowers (Antirrhinum majus L.) is usually determined by the stem-bending rate, rather than petal senescence, because they cannot be used for commercial purpose once their stems are bent. Stem bending often occurs in snapdragon cut flowers during a short vase-life period. Research has been conducted using ET and ET-action inhibitors, such as silver thiosulfate (STS) and 1-methylcyclopropene (1-MCP), to investigate whether ET is involved as a positive regulator in the stem-bending mechanism of snapdragon (PhilosophHadas et al, 1996, 1999; Woltering et al, 2005; Çelikel et al, 2010). In a study reported by Çelikel et al (2010), pretreatment of the stems with STS or 1-MCP did not significantly affect the gravitropic curvature and bending of snapdragon flowers compared with the control, while 1-MCP-treated stems even showed slightly increased bending compared with ET-treated stems (Woltering et al, 2005). In the studies reported by Philosoph-Hadas et al (1996, 1999), STS or 1-MCP blocked the gravitropic response of the snapdragon flowers.
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