Abstract
Some of the compounds binding to the ethylene receptor induce an ethylene response, but others prevent it. The compounds preventing an ethylene response have been developed into a means for ...protecting plants against ethylene and extending the life of some plant material. 1-Methylcyclopropene (1-MCP), a compound now commercially available under the names EthylBloc® and SmartFresh™, is currently being used on flowers, fruit and vegetables with great success. In ethylene sensitive flowers, among other responses, it prevents senescence and abscission of plant organs; in fruit and vegetables it slows down the ripening process. Other similar compounds are now being developed for a range of methods of application.
For a vast number of ornamental species, blocking the plant’s response to ethylene is an efficient strategy to enhance the longevity of the flowers. The most effective ways to conduct such ...interference will be reviewed in this paper.
A large number of chemical compounds have been evaluated for their effects on ethylene production and perception. Among these are a range of strained olefines. This has resulted in the discovery that cyclopropenes, among them 1-methylcyclopropene (1-MCP) and a number of other substituted cyclopropenes effectively block ethylene responses at the receptor level. A lot of testing remains to be done to uncover the full potential of these compounds, but they do offer promising new ways to extend the postharvest life of ornamentals.
Also genetic modification appears to be a very effective way in controlling of ethylene synthesis and perception. Attempts to use both a reduced endogenous ethylene production and a reduced sensitivity to ethylene will be reviewed. Among these the use of the mutant ethylene receptor gene,
etr1-1, from
Arabidopsis seems most promising, especially when it is expressed under the control of a flower specific promoter.
Ethylene is known to cause many undesirable effects in a range of ornamental plants. Blocking ethylene responses is an efficient strategy to enhance the longevity of flowers and display life of ...potted plants that are ethylene sensitive. One of the most effective and inexpensive ways to conduct such interference is through the use of chemical compounds. Since the early 1970s silver thiosulfate (STS) has been widely used as a powerful ethylene antagonist, but in the last two decades a large number of volatile chemical compounds have been evaluated for their effect on ethylene production and perception. This has resulted in the discovery that cyclopropenes effectively block ethylene responses at the receptor level. The most effective among these are 1-methylcyclopropene (1-MCP) and a number of other substituted cyclopropenes. 1-MCP has been successfully commercialized and is presently worldwide used for ethylene sensitive horticulture crops. Because of the volatile character of most cyclopropenes, treatment of plant material is limited to enclosed systems. For outdoor applications, non-volatile formulations are desired. In recent years several newly synthesized non-volatile cyclopropenes with a methyl group in the 1-position, on which a substituted amine was attached, have been reported. When diluted with a weak acid such as acetic, formic, carbonic or phosphoric, a non-volatile salt is formed which can be applied as a liquid solution. N,N-dipropyl(1-cyclopropenyl-methyl)amine (DPCA) applied to plant material as a gas, dip or spray has been shown as an effective ethylene blocker in several plant species. Another novel water soluble, non-phytotoxic, and odorless inhibitor of ethylene action, 3-cyclopropyl-1-enyl-propanoic acid sodium salt (CPAS), has been tested on carnation and petunia, and on several edible products. All tested plant material was effectively protected against undesirable effects of ethylene. A lot of testing remains to be done to uncover the full potential of these compounds, but they do offer promising new ways to improve the postharvest quality and longevity of ornamentals.
Protoplasts were isolated from leaves of in vitro-grown shoot cultures of different Petunia and Calibrachoa genotypes by enzyme digestion with 0.6% macerozyme R-10 and 2.0% cellulase R-10. Shoot ...regeneration was achieved in five out of nine Calibrachoa and three out of four Petunia genotypes. Protoplast yield and frequency of shoot regeneration varied among experiments and genotypes. Among all regenerants, few morphological changes, such as chlorophyll deficiency, variegated leaves, and polyploidization, were observed.
This study is the first report of gene manipulation to alter flower colour in the genus Campanula. The experiment was designed using Campanula carpatica ‘Improved Blue Uniform’ (IBU) with two main ...purposes: to generate a red flower colour by down-regulation of delphinidin production through RNAi silencing of the flavonoid 3', 5' hydroxylase (F3'5'H) gene, and to improve vase-life by inducing insensitivity to ethylene using the ethylene-resistant 1-1 (etr1-1) gene. Three independent transgenic lines were obtained after genetic transformation via Agrobacterium tumefaciens strain GV3101. Southern blot analysis was performed to determine the integrated T-DNA copy number, and reverse transcription-polymerase chain reactions (RT-PCR) were performed to evaluate expression of the F3'5'H and flavonoid 3' hydroxylase (F3'H) genes. An ethylene sensitivity test was conducted to evaluate the tolerance of the transformed plants to exposure to ethylene. Southern blot analysis revealed the integration of two or three T-DNA copies in each of the three transformed lines. The flower colour of the transformed lines was not visually altered, and expression of the F3'5'H and F3'H genes in all three transformed and in non-transformed lines was confirmed by RT-PCR. Although all flowers on non-transformed Campanula plants were senescent 6 d after exposure to ethylene, 63.3% of the flowers on transgenic line 11-213 and 86.4% of the flowers on transgenic line 21-1 survived. The ethylene sensitivity test showed that transformed plants exposed to ethylene showed a significant delay in senescence compared to non-transformed plants.
This work describes compact phenotypes of Kalanchoë blossfeldiana and Petunia hybrida plants harboring a constitutively overexpressed gibberellin 2-oxidase (GA ₂ ox) transgene. A GA ₂ ox gene from ...Nicotiana tabacum under the control of the Ca35S promoter was introduced into the pCAMBIA1303 plasmid. The cloning vector was introduced into leaf explants of Kalanchoë and Petunia via Agrobacterium-mediated transformation. Putative transformants were analysed for the presence, integration and expression of the transgene using polymerase chain reaction (PCR), reverse-transcription (RT)-PCR, and Southern blot analysis, respectively. Phenotypic evaluations revealed that the mean lengths of the Kalanchoë transgenic lines were two-fold shorter than those of wild-type control plants, although the mean numbers of nodes were similar. Moreover, the mean lengths of inflorescence stems of the Kalanchoë transgenic lines were almost three-fold shorter than those of the wild-type control plants. Similarly, the mean lengths of Petunia transgenic lines were four-fold shorter than those of the wild-type plants, except for a single line, while the mean numbers of nodes were either similar or higher in the transgenic lines than in the wild-type control plants. In transgenic lines of both Kalanchoë and Petunia, delayed flowering was observed with a mean of 24 days for Kalanchoë and a range of three to 12 days for Petunia. Although the flower morphology of the transgenic lines did not exhibit any differences from their respective wild-type control plants, transgenic lines of both species exhibited darker green pigmented leaves containing an approximately two-fold increase in chlorophyll contents over the wild-type control plants.
Ethylene has been proved to create adverse effects in ethylene sensitive floriculture crops. A powerful strategy in preventing ethylene responses in ornamentals and subsequently increasing their ...display life and longevity of flowers is blocking ethylene binding sites. Use of chemical compounds is one of the most efficient and low-cost methods to execute such interference. The most powerful ethylene antagonist, which has been used in ornamental industry for more than 40 years, is silver thiosulfate (STS). However, because of the toxic nature of the silver ion alternative chemicals have been tested in the last two decades for their ability in blocking ethylene synthesis and perception. Several gaseous compounds have been evaluated, which lead to the discovery of 1-substituted cyclopropenes (1-CPs), which effectively prevent ethylene action at the receptor level. The most simple of 1-CPsis is 1-Methylcyclopropene (1-MCP), which has been commercialized and presently is successfully used worldwide for ethylene sensitive horticulture crops, including edible and ornamental crops. The volatile character of the 1-CPs limited their use to enclosed systems. Non-volatile formulations for e.g., outdoor applications were therefore needed. Recently, several newly synthesized non-volatile cyclopropenes with a methyl group in the 1-position, on which a substituted amine was attached, have been tested. A non-volatile salt, N,N-dipropyl (1-cyclopropenyl-methyl) amine (DPCA), which can be applied to plant material as a gas, dip or spray has been reported as an effective ethylene blocker in edible and ornamental plant species. The tested plant material was effectively protected against undesirable effects of ethylene. One of the effective ways to control ethylene synthesis and ethylene responses in plants is genetic modification. The introduction of the mutant ethylene receptor gene, etr1-1, from Arabidopsis has been proved as the most promising for such purpose, especially when its expression is controlled by a flower specific promoter. Several ornamental species, which were genetically modified with etr1-1 mutant gene showed a strong ethylene tolerance.
To clarify the molecular mechanism of flower development in Rosa hybrid L. different MADS-box-genes were investigated in normally developed flowers and in malformed flowers (similar C-function ...mutation). Expression levels of all A, B and C class genes were examined by qRT-PCR in different flower organs of both types of flowers. Expression patterns of MADS-box genes in early organ development were investigated by in-situ RT-PCR. Three different unknown APETALA1 homologous cDNA's were isolated and designated as RhAP1-1, RhAP1-2 and RhFUL. Exclusive expression of APETALA1 homologue genes RhAP1-1 and RhAP1-2 in whorl 1 and 2 of rose flowers demonstrate that the expression patterns are similar to APETALA1 homologue genes in other plant species. In contrast, RhFUL showed a unique expression pattern and was expressed only in sepals. Comparison of expression patterns between normal and malformed flowers demonstrated that two different B class genes were unaffected. All A class genes were up regulated and two C class genes were down regulated in all flower organs. Suppression of the C class genes RhC1 and RhC2 may be the reason for expression of RhAP1-1, RhAP1-2 and RhFUL in whorls 3 and 4 that lead to the malformed flower phenotype. Possible reasons for suppression of class C genes in early bud stages are discussed.
The Green Fluorescent Protein (GFP) from the jellyfish Aequorea Victoria has proven to be a convenient and powerful vital marker in transgenic studies. Its expression can be detected ...non-destructively, in real time, simply by UV-light excitation. This property of GFP holds promise in monitoring the presence and expression of transgenes in higher plants. Based on a transient gene expression assay, the function of two GFP genes was tested: mGFP-4 (Haseloff et al., 1997) and smRS-GFP (Davis and Vierstra, 1998). The intensity of smRS-GFP fluorescence was higher than that of mGFP-4 in Petunia and easier to distinguish from other unspecific fluorescent signals. First stable transformation experiments in four commercially relevant Petunia cultivars involved the vector pMen65smRS-GFP containing nptII gene. This vector resulted in clearly detectable GFP expressing callus and made it possible to visually select exclusively for GFP. Selection using GFP only versus GFP and kanamycin selection was compared regarding the transformation efficiencies. The detection of integration the transgene via southern hybridization revealed single and multiple integrations of smRS-GFP in Petunia. Single copy plants showed intensive expression in all parts of the plants, while rising copy numbers led to only weak or partial expression of smRS-GFP. In this study, the possibility to select transgenic plants based on their GFP expression without applying antibiotic or herbicide resistance genes is shown.
