Involvement of Sodium Nitroprusside (SNP) in the Mechanism That Delays Stem Bending of Different Gerbera Cultivars

Abstract

Longevity of cut flowers of many gerbera cultivars (Gerbera jamesonii) is typically short because of stem bending; hence, stem bending that occurs during the early vase life period is a major problem in gerbera. Here, we investigated the effects of sodium nitroprusside (SNP) on the delay of stem bending in the gerbera cultivars, Alliance, Rosalin, and Bintang, by examining relative fresh weight, bacterial density in the vase solution, transcriptional analysis of a lignin biosynthesis gene, antioxidant activity, and xylem blockage. All three gerbera cultivars responded to SNP by delaying stem bending, compared to the controls; however, the responses were dose- and cultivar-dependent. Among the treatments, SNP at 20 mg L-1 was the best to delay stem bending in Alliance, while dosages of 10 and 5 mg L-1 were the best for Rosalin and Bintang, respectively. However, stem bending in Alliance and Rosalin was faster than in Bintang, indicating a discrepancy influenced by genotype. According to our analysis of the role of SNP in the delay of stem bending, the results revealed that SNP treatment inhibited bacterial growth and xylem blockage, enhanced expression levels of a lignin biosynthesis gene, and maintained antioxidant activities. Therefore, it is suggested that the cause of stem bending is associated with the above-mentioned parameters and SNP is involved in the mechanism that delays stem bending in the different gerbera cultivars.

Ethylene Acts as a Negative Regulator of the Stem-Bending Mechanism of Different Cut Snapdragon Cultivars

“…The occurrence of stem bending caused by a low lignin content may be explained by the fact that a low content of this molecule might not provide sufficient rigidity to the stem and vascular tissue, which would result in poor mechanical resistance to the whole-flower spikes and disruption of water and mineral transport to the flowers ( Steinitz, 1982 , 1983 ), thereby leading to rapid stem bending. A positive association between stem bending and low lignin content was reported in previous studies ( Steinitz, 1982 , 1983 ; Marousky, 1986 ; Perik et al, 2014 ; Naing et al, 2017 ). In this study, the presence of a higher lignin content in the ethephon treatment compared with other treatments may be due to the higher accumulation of ET in the former, because ET has been reported to promote lignification by triggering lignin biosynthetic genes ( PAL and 4CL ) and to improve stem strength and resistance, to delay stem bending ( Prasad and Cline, 1987 ; Brown, 1990 ; Hyodo et al, 1991 ; Ievinsh and Romanovskaya, 1991 ; Sitbon et al, 1999 ; Luo et al, 2007 ; Huang et al, 2013 ; Mangieri et al, 2016 ; Ye et al, 2016 ).…”

“…Stem bending in cut flowers is generally caused by the presence of a low lignin content in the stems (Marousky, 1986;Naing et al, 2017), which leads to an inability to strengthen the rigidity of the stem and the vascular tissue (Steinitz, 1982(Steinitz, , 1983). This will result in reduction of the mechanical resistance to the whole-flower spikes, as well as disruption of water and mineral transport to the flowers, which will in turn cause rapid stem bending.…”

Genome-Wide Analysis of the NF-YB Gene Family in Gossypium hirsutum L. and Characterization of the Role of GhDNF-YB22 in Embryogenesis

“…Previous studies have reported that NF-YB genes play important roles in plant developmental processes (e.g., in late embryogenesis, flowering time, drought tolerance, etc.) [ 46 ]. In the present study, we identified the tissue-specific expression patterns of GhNF-YB genes in a variety of tissues, where the results show that most of the NF-YB genes are expressed ubiquitously, with the exception of a few genes that are expressed in specific tissues ( Figure 5 ).…”

Characterizing the effects of different chemicals on stem bending of cut snapdragon flower

“…We found that SNP did not effectively inhibit curvature when the vase life period was extended to 9 days. However, SNP has been reported to delay stem bending in gerberas and Calendula officinalis [ 3 , 14 , 15 ]. This different outcome could be due to the difference in the nature of the stem structures between snapdragon and gerberas and Calendula officinalis .…”

“…Ethephon has been shown to have promoting effects on lignification [ 2 , 12 , 13 ]. Delaying of stem bending by sodium nitroprusside (SNP) has been reported in gerbera and Calendula officinalis L. [ 3 , 14 , 15 ], whereas SNP promoted lignification and delayed the stem bending in cut gerbera [ 3 ]. Although ethephon has a promoting effect on lignification and preventive effect on stem bending [ 2 , 11 – 13 ], as described above, the ethylene inhibitors STS or 1-MCP blocked the gravitropic bending of snapdragon [ 6 , 7 ].…”