Ethylene Production In Flowers Research Articles

The effect of strobilurin on ethylene production in flowers, yield and quality parameters of processing tomato grown under a moderate water stress condition in Mediterranean area

This research was conducted in Southern Italy over two growing seasons to evaluate the effect of strobilurin application on the ethylene production of flowers (EF) and on the yield and quality parameters of processing tomato grown under moderate water deficit conditions. The following two irrigation regimes were applied: IR100, full irrigation that restores 100% of the maximum crop evapotranspiration (ETc) and IR75, which is 75% of the amount of water of IR100. Furthermore, from the beginning of flowering two fungicide treatments were applied three times: fungicide treatment without strobilurin (ST0) and strobilurin fungicide with an azoxystrobin based product (STaz). At full flowering, ethylene production in the flowers (EF) was determined. At harvest, the main yield and qualitative parameters were evaluated. The strobilurin treatment caused a significant decrease of EF, which was less evident in the first warmer year than in the second. This result was presumably because of the interference of high temperatures on the inhibition of ethylene synthesis described for the strobilurin. In contrast, the decrease of EF due to strobilurin treatment was more evident under IR75 than under IR100. Finally, the decrease in the number of marketable fruits with respect to the EF increase was lower under strobilurin treatment presumably because of the protective effect of this molecule on the flower drop. Further studies are needed to investigate this hypothesis in greater detail.

Pollination increases ethylene production in Lilium hybrida cv. Brindisi flowers but does not affect the time to tepal senescence or tepal abscission

In many species, pollination induces a rapid increase in ethylene production, which induces early petal senescence, petal abscission, or flower closure. Cross-pollination in Lilium hybrida cv. Brindisi resulted in a small increase in flower ethylene production. In intact plants and in isolated flowers, pollination had no effect on the time to tepal senescence or tepal abscission. When applied to closed buds of unpollinated flowers, exogenous ethylene slightly hastened the time to tepal senescence and abscission. However, exogenous ethylene had no effect when the flowers had just opened, i.e. at the time of pollination. Experiments with silver thiosulphate, which blocks the ethylene receptor, indicated that endogenous ethylene had a slight effect on the regulation of tepal senescence and tepal abscission, although only at the time the tepals were still inside buds and not in open flowers. Low ethylene-sensitivity after anthesis therefore explains why pollination had no effect on the processes studied.

IMPROVING PRODUCTION QUALITY OF LILY FLOWERS BY USING ARBUSCULAR MYCORRHIZAL FUNGI AND YEAST AS A VIABLE ALTERNATIVE TO ETHYLENE INHIBITORS

The experimental trial was consummated throughout two successive seasons (2010 and 2011) at Ornamental Plants Research and Landscape Dep., Hort. Res. Inst, Giza. It intended to find out the individual effect of mycorrhizal colonization and yeast or the combination between both as a biofertilizer. Besides the combined effect with half dose of NPK as preharvest treatments on ethylene production by flowers and keeping quality of cut flowers of Lilium asiaticum cv. Nello. The obtained results showed that all treatments significantly stimulated most of the studied characters compared with that gained from control plants. The inoculation of Lilium with either AM fungi and /or yeast supported the highest values of flower vase life and longevity of flowers and leaves. The addition of AM fungi solely or combined with yeast and/ or ½ NPK gave the maximum flower opening percentage, increased flower diameter, water uptake as well as the percentage of increase in fresh weight. The same combination revealed that leaves had higher total chlorophylls content and the flowers had higher total sugars%. In respect to ethylene production, it was noticed that Mycorrhizal colonization either solely or in combination with yeast and/or ½ NPK decreased flower ethylene production. Thus, mycorrhizal colonization may be a viable alternative to toxic ethylene inhibitors such as silver thiosulfate, since STS has proven to be environmental pollutant.

Analysis of genomic DNA of DcACS1, a 1-aminocyclopropane-1-carboxylate synthase gene, expressed in senescing petals of carnation (Dianthus caryophyllus) and its orthologous genes in D. superbus var. longicalycinus

Carnation (Dianthus caryophyllus) flowers exhibit climacteric ethylene production followed by petal wilting, a senescence symptom. DcACS1, which encodes 1-aminocyclopropane-1-carboxylate synthase (ACS), is a gene involved in this phenomenon. We determined the genomic DNA structure of DcACS1 by genomic PCR. In the genome of 'Light Pink Barbara', we found two distinct nucleotide sequences: one corresponding to the gene previously shown as DcACS1, designated here as DcACS1a, and the other novel one designated as DcACS1b. It was revealed that both DcACS1a and DcACS1b have five exons and four introns. These two genes had almost identical nucleotide sequences in exons, but not in some introns and 3'-UTR. Analysis of transcript accumulation revealed that DcACS1b is expressed in senescing petals as well as DcACS1a. Genomic PCR analysis of 32 carnation cultivars showed that most cultivars have only DcACS1a and some have both DcACS1a and DcACS1b. Moreover, we found two DcACS1 orthologous genes with different nucleotide sequences from D. superbus var. longicalycinus, and designated them as DsuACS1a and DsuACS1b. Petals of D. superbus var. longicalycinus produced ethylene in response to exogenous ethylene, accompanying accumulation of DsuACS1 transcripts. These data suggest that climacteric ethylene production in flowers was genetically established before the cultivation of carnation.

Senescence of Eustoma Flowers as Affected by Pollinated Area of the Stigmatic Surface

Senescence of Eustoma flowers is accelerated by pollination which is accompanied by an increase in ethylene production by flowers. We investigated the influence of pollinating different areas of the stigmatic surface on senescence in the flowers of 6 Eustoma cultivars. Anthers were removed from the flowers whose stigma had not yet opened. After the stigmas opened, freshly collected pollen from anthers of same cultivar were placed on them. The pollination levels on stigma were all area, 1/8 area or none (control). Senescence of flowers was significantly accelerated by all and 1/8 area pollination compared with the control. All area-pollinated flowers wilted significantly earlier than did 1/8 area-pollinated ones in three cultivars. In the remaining three cultivars, senescence of flowers by all area pollination tended to be earlier than that of 1/8 area pollination. In ‘Asuka-no-nami’ flowers, ethylene production of flowers rapidly increased 1 day after all area pollination. However, in flowers with 1/8 area pollination, ethylene production slowly increased for 3 days after pollination. A large number of pollen tubes reached the base of the style 2 days after pollination in the all area-pollinated flowers, but on 3rd day in the 1/8 area-pollinated flowers. All area-pollinated flowers required silver thiosulfate complex (STS) at high concentration to delay senescence induced by pollination, compared with the 1/8 area-pollinated flowers. These results suggest that in Eustoma flowers, senescence that is induced by pollination, depends on the pollinated area of the stigmatic surface which resulted in ethylene production.

LONGEVITY AND ETHYLENE PRODUCTION DURING DEVELOPMENT STAGES OF TWO CULTIVARS OF LILIUM FLOWERS AGEING ON PLANT OR IN VASE

Cut lily (Lilium L.) flowers may be considered as flowers with low sensitivity to ethylene. Ethylene inhibitors did not always increase their vase life, and the effect of other treatments varied with cultivar. The aim of this work was to investigate the ethylene production and the flower longevity of Asiatic lilies (Lilium L. hybrid 'Elite' and 'Prato') during natural senescence (intact flowers) and after harvest (with or without storage at 4°C). Flower longevity was significantly reduced by one or two days following detachment and cold storage, respectively. Blasting or incomplete opening of apical buds was observed only in cut inflorescences. The endogenous ethylene production of flowers was very low and it increased during senescence. Following flower detachment, neither a climacteric peak nor a higher ethylene evolution, were observed. Pistils produced higher levels of ethylene during the initial development stage, when the bud was still closed, and lower levels during advanced stages of development. Our results suggest that, although known to have low sensitivity to ethylene, Lilium flowers and their individual flower organs, mainly the pistils, produce ethylene. The hormone mediates normal flower development and senescence processes, but it may not play a primary role.

TOWARDS UNDERSTANDING THE ONSET OF PETAL SENESCENCE: ANALYSIS OF ETHYLENE PRODUCTION IN THE LONG-LASTING CARNATION CV. WHITE CANDLE

In senescing carnation (Dianthus caryophyllus L.) flowers, ethylene is produced from the gynoecium, and acts as a diffusible signal received by petals to induce the expression of 1-aminocyclopropane-1-carboxylate (ACC) synthase (DC-ACS1) and ACC oxidase (DC-ACO1) genes in the petals. This results in autocatalytic ethylene production in the petals. We investigated ethylene production in cut flowers of cv. White Candle, which produce ethylene only in trace amounts and have a long vase life. The low ethylene production in these flowers was due to low ethylene production in the gynoecium, accompanied by low accumulation of ACC synthase transcripts. These findings further support the importance of ethylene production from the gynoecium in the senescence of carnation flowers. Cv. White Candle flowers had water relations that were different from those in cv. Light Pink Barbara, a cultivar that showed the normal climacteric rise of ethylene production during senescence. We discuss a factor that possibly induces ethylene production in the carnation gynoecium.

BA and Sucrose Increase Vase Life of Cut Eustoma Flowers

An experiment was conducted to measure the effects of pulse treatments of BA, sucrose, and BA before, after, or with sucrose, on the vase life of cut Eustoma flowers. A BA pulse at 50 mg·L-1 before 4% sucrose promoted the longevity of cut Eustoma flowers better than other treatments. Simultaneously, sucrose, glucose, and mannose concentrations in flowers during vase periods were maintained at higher levels in double pulse treatments than in the single pulses. Ethylene production in flowers 2 days after vase treatment was highest in the BA-treated flowers; intermediate in flowers pulsed with BA before, after, or with sucrose; and lowest in sucrose-treated flowers. Although a BA pulse increased ethylene production over that of controls, it inhibited senescence in cut Eustoma flowers. Respiration in flowers pulse-treated with sucrose or with BA before, after, or with sucrose, was significantly higher than that in controls. Results suggest that the vase life of cut Eustoma flowers is improved by either BA or sucrose in vase solution and especially when BA was pulsed before the sucrose pulse. Chemical name used: N6-benzyladenine (BA).

Soluble carbohydrates in Delphinium and their influence on sepal abscission in cut flowers

A carbohydrate other than sucrose, glucose, fructose and myo‐inositol was detected in sepal extracts of Delphinium. This compound was identified as mannitol by 1H‐NMR. Mannitol was the major carbohydrate in all examined organs: the sepal, the other parts of the flower, the stem and leaves. Mannitol as well as glucose (both at 0.55 M), fed to cut Delphinium flowers, similarly delayed the abscission of sepals. 3‐O‐methyl glucose (3‐OMG) and polyethylene glycol 200 at the same molar concentrations had no such effect. The treatment with glucose markedly increased the concentrations of glucose and fructose in the sepals without changing the concentrations of sucrose and mannitol. On the other hand, the treatment with mannitol increased the concentrations of glucose and fructose in addition to mannitol in the sepals, suggesting that mannitol is metabolized in Delphinium flowers. The treatment with 3‐OMG increased the concentration of 3‐OMG but not other carbohydrates. Mannitol and glucose similarly delayed the increase in ethylene production in flowers, but 3‐OMG did not. The sensitivity to ethylene was similarly reduced by the treatment with glucose and mannitol, but not by 3‐OMG. These results suggest that the treatment with mannitol, a major carbohydrate in Delphinium, delayed the abscission of sepals by reducing the sensitivity to ethylene. Mannitol further acted, not merely as an osmolyte, but as an apparent source for carbohydrate metabolism in the flower.

Effect of mycorrhizal colonization and phosphorus on ethylene production by snapdragon ( Antirrhinum majus L.) flowers

We determined the effects of phosphorus (P) concentration and mycorrhizal colonization on ethylene production by flowers of snapdragons (Antirrhinum majus L.). Mycorrhizal colonization in a soil-less medium did not significantly affect the total number of flowers per spike or flower P concentration, but it significantly increased flower vase-life and significantly decreased flower ethylene production. This demonstrates for the first time that mycorrhizal colonization can have a non-localized effect on host ethylene production. The reduction in ethylene production caused by mycorrhizal colonization was as large as the variation in ethylene production among snapdragon cultivars. Thus, mycorrhizal colonization may be a viable alternative to toxic ethylene inhibitors such as silver thiosulfate. Increased fertilizer P concentration (15 versus 3 μg P ml–1) significantly increased plant fresh weight and the total number of flowers per spike. In contrast to mycorrhizal colonization, increased fertilizer P concentration resulted in an increase in ethylene production. There was no significant effect of fertilizer P concentration on vase-life. This suggests that factors other than ethylene have at least partial control over vase-life. Postharvest amendment of individual flowers with phosphate also significantly increased flower ethylene production. Phosphorus apparently does not mediate the mycorrhizal effect because mycorrhizal colonization decreased ethylene production without significantly influencing flower P concentration. Moreover, treatment with phosphate increased flower ethylene production. Mycorrhizal colonization did not significantly influence response to exogenous ethylene.

Role of Ethylene on Flower Senescence of Torenia.

Flower senescence of Torenia fournieri was investigated in relation to ethylene production and sensitivity. Ethylene production of flowers increased with flower senescence ; pistil contributed to climacteric increase of ethylene production whereas other organs such as the petal, stamen, and calyx did not. Flowers were not sensitive to ethylene on the day of anthesis, but developed sensitivity as the flower senesced. Pollination and wounding of stigma markedly accelerated abscission of flowers, which was accompanied by climacteric ethylene production. Climacteric ethylene, following pollination and stigma wounding, was mainly produced by the pistil, particularly the style with stigma. The abscission of the intact, pollinated and stigma-wounded flowers was significantly inhibited by treatment with silver thiosulfate complex (STS), an ethylene action inhibitor. These results clearly show that the flower senescence of Torenia is mainly regulated by ethylene.

Role of ethylene in senescence of cut Eustoma flowers

Abstract Flower senescence of Eustoma grandiflorum was investigated in relation to ethylene production and sensitivity to ethylene. Ethylene production of flowers increased with flower senescence. Ethylene was mainly produced in the pistil, in particular in the style, and production in the petal increased with flower senescence. Flowers were not sensitive to ethylene at anthesis, but became more sensitive with increasing senescence. Treatment with silver thiosulphate (STS), an ethylene action inhibitor, extended flower longevity. STS inhibited ethylene production from the whole flower, particularly that from the petal. Thus, ethylene is considered to be involved in the flower senescence of Eustoma.

Effects of Ethephon on Growth and Oil Yield of Palmarosa (Cymbopogon martinii Wats.)

ABSTRACT Ethephon [(2-chloroethyl) phosphonic acid, Ethrel, Composan] was evaluated in field trials as a chemical hybridizing agent on four varieties of palmarosa (Cymbopogon martinii): PRC-1, Tripta, Trishna, and Composite. Application of 500 μg/ml ethephon to foliage either as a mist or by wrapping ethephon-soaked cotton around the stem during the vegetative and anthesis stages initiated increases in growth and yield attributable to heterosis. A positive correlation (r2 = 0.81) between ethephon application and yield of dry matter and ethephon application and essential oil with enhanced geraniol levels was obtained, suggesting ethephon treatment is an effective chemical hybridizing agent in palmarosa. Ethephon also appeared to stimulate ethylene production in flowers of palmarosa, resulting in male sterility and premature anther-petal senescence.

Sites of ethylene production in flowers of sweet pea ( Lathyrus odoratus L.)

Flowers of sweet pea showed climacteric rise in ethylene production. The style and stigma, collectively, showed an initial rise in ethylene production which later extended to the other flower parts. A very high amount of ethylene was produced by the staminal sheath which is suggested to play an important role in flower senescence.

Sites of ethylene production in the pollinated and unpollinated senescing carnation (Dianthus caryophyllus) inflorescence

Production of endogenous ethylene from the styles, ovary and petals of pollinated and unpollinated flowers of Dianthus caryophyllus L. was measured. The rate of ethylene production of cut, unpollinated flowers aged in water at 18°C was low until the onset of petal wilting, when a rapid surge of ethylene occurred in all tissues. The flower ethylene production was evolved mostly from the styles and petals. The bases of petals from unpollinated, senescing flowers evolved ethylene faster and sometimes earlier than the upper parts. Treatment of cut flowers with propylene, an ethylene analogue, accelerated wilting of flower petals and promoted endogenous ethylene production in all flower tissues. Pollination of intact flowers also promoted endogenous ethylene production and caused accelerated petal wilting within 2-3 days from pollination. Although the data are consistent with the hypothesis that ethylene forms a link between pollination of the style and petal wilting, in the unpollinated flower the style and petals can evolve a surge of ethylene independently of each other, about the time when the petals irreversibly wilt. The results are discussed in relation to the role of ethylene in flower senescence.

Regulation of Senescence in Carnation (Dianthus caryophyllus)

Abscisic acid hastened senescence of carnation flowers and this was preceded by stimulation of accelerated ethylene production. Carbon dioxide delayed the onset of autocatalytic ethylene production in flowers regardless of treatment with abscisic acid. Flowers exhibited a low and transient climacteric of ethylene production without wilting while in 4% carbon dioxide and underwent accelerated ethylene production culminating in wilting when removed from carbon dioxide. Hypobaric ventilation, which lowers ethylene to hyponormal levels within tissues, extended flower longevity and largely negated enhancement of senescence by abscisic acid. Supplementing hypobarically ventilated flowers with ethylene hastened senescence irrespective of abscisic acid treatment. Collectively, the data indicate that abscisic acid hastens senescence of carnations largely as a result of advancing the onset of autocatalytic ethylene production.