Ethylene Production In Shoots Research Articles

Drought and re-watering modify ethylene production and sensitivity, and are associated with coffee anthesis

Coffee flowering requires a period of water deficit followed by rainfall to break flower bud dormancy and promote anthesis. Since drought followed by re-watering can increase shoot ethylene production, we investigated changes in root, leaf and flower bud ethylene production and expression of genes within the ethylene biosynthesis and signalling pathways and their relationship to coffee flowering. Drought decreased foliar and flower bud ethylene production without changing root ethylene production, even though all tissues likely accumulated the ethylene precursor ACC (1-aminocyclopropane-1-carboxylic acid), since ACS gene expression was maintained while ACO gene expression decreased. The ethylene receptor CaETR4-like was not differentially expressed in leaves under water deficit, but it was downregulated in roots. Re-watering restored shoot ethylene production, which seems important in promoting anthesis. 1-MCP (1- Methylcyclopropene), an ethylene action inhibitor, triggered coffee anthesis without re-watering the plants, which hitherto was considered essential to allow flowering. 1-MCP positively regulated foliar and flower bud ethylene biosynthesis genes (CaACS1-like and CaACO1-like), similar to re-watering, and downregulated CaETR4-like, suggesting that changes in ethylene levels and sensitivity are required to promote coffee anthesis. Thus, drought and re-watering-induced changes in ethylene levels and sensitivity allow coffee flowering, while the growth regulator 1-MCP can potentially regulate anthesis time and intensity.

Light Signaling Regulates Tulip Organ Growth and Ethylene Production in a Tissue-Specific Manner

Premise of research. Plants growing under physical or leaf canopy shade often exhibit increases in shoot growth that allow for additional exposure to irradiance from sunlight. These shaded plants also usually exhibit an accelerated flowering, though the effect of shade light on growth of flower organs has not been well studied. These growth changes in shoot organs induced by shade light signaling are regulated in a negative manner by ethylene in a number of plant species; that is, shading reduces shoot ethylene production, thereby increasing shoot growth.Methodology. Tulip (Tulipa gesneriana L., Liliaceae) plants were selected as a model system, one where floral organ development occurs in the bulb before exposure to shade light. This allows any effects of shade light signaling on floral organ growth to be uncoupled from effects on development. Therefore, following a period of low temperature, tulip bulbs were exposed to simulated sunlight with and without physical or canopy shade.Pivotal results. Both a ...

Ammonium-induced shoot ethylene production is associated with the inhibition of lateral root formation in Arabidopsis

Foliar NH4(+) exposure is linked to inhibition of lateral root (LR) formation. Here, the role of shoot ethylene in NH4(+)-induced inhibition of LR formation in Arabidopsis was investigated using wild-type and mutant lines that show either blocked ethylene signalling (etr1) or enhanced ethylene synthesis (eto1, xbat32). NH4(+) exposure of wild-type Arabidopsis led to pronounced inhibition of LR production chiefly in the distal root, and triggered ethylene evolution and enhanced activity of the ethylene reporter EBS:GUS in the shoot. It is shown that shoot contact with NH4(+) is necessary to stimulate shoot ethylene evolution. The ethylene antagonists Ag(+) and aminoethoxyvinylglycine (AVG) mitigated LR inhibition under NH4(+) treatment. The decrease in LR production was significantly greater for eto1-1 and xbat32 and significantly less for etr1-3. Enhanced shoot ethylene synthesis/signalling blocked recovery of LR production when auxin was applied in the presence of NH4(+) and negatively impacted shoot AUX1 expression. The findings highlight the important role of shoot ethylene evolution in NH4(+)-mediated inhibition of LR formation.

Responses of ethylene biosynthesis to saline stress in seedlings of eight plant species

The effect of salinity (100 mM NaCl) on ethylene metabolism in the early phase of vegetative development of several plant species has been investigated. The effects of saline treatment on shoot and root growth, ranged in sensitivity with respect to species: pepper (Capsicum annum L. cv Pairal) > tomato (Lycopersicon esculentum Mill. cv Malpica) > broccoli (Brassica oleraceae L. var. Italica Plenk. cv Marathon F1) ≅ lettuce (Lactuca sativa var. longifolia Lam. cv Inverna) ≅ melon (Cucumis melo L. cv Ruano F1, Roche type) > bean (Phaseolus vulgaris L. cv. Gator Green 15) ≅ spinach (Spinacia oleracea L. cv Boeing) > beetroot (Beta vulgaris L. var. crassa (Alef.) J. Helm. cv Detroit). After saline treatment, ethylene production increased 4.2-fold in pepper shoots. Significant increases were also found in shoots of tomato, broccoli and bean. In contrast, salinity decreased shoot ethylene production rate in melon, spinach, and beetroot. In roots, the general effect of salinity was a decrease in ethylene production, especially in broccoli and bean, except in tomato root, in which a sharp increase in ethylene production occurred. In general, saline treatment increased total ACC concentration in both shoot and root in most of the plant species examined, which was related to plant sensitivity to salinity. For example, pepper shoot was the most sensitive to saline treatment, showing the highest fresh weight inhibition and the highest increase in total ACC concentration (8.5-fold), while, beetroot was less affected by salinity and showed no effect on total ACC concentration in response to saline treatment.

Circadian Ethylene Synthesis in Sorghum bicolor: Expression and Control of the System at the Whole Plant Level

Ethylene production by sorghum is rhythmic and the amplitude of the rhythm is increased both by dim, far-red enriched light and in mutant plants deficient in phytochrome B. The mechanisms involved in controlling ethylene production were examined in detail by measuring the rate of ethylene production among organs and tissues, examining the organ-specific levels of ACC (1-aminocyclopropane-1-carboxylic acid, the ethylene precursor) and investigating the contribution of the roots to shoot ethylene production. The results demonstrate that the expanding leaves were the major source of ethylene under dim, far-red enriched light and in the phytochrome B mutant. Enhanced ethylene production by the expanding leaf appeared to be the result of targeted delivery of ACC to this tissue. Root ACC levels were much higher than those in the shoot but roots converted much less of this endogenous ACC to ethylene. Applying ACC to the roots had only a marginal effect on their ethylene production, but greatly increased that of the shoots. Decapitated shoots continued to produce ethylene in a rhythmic pattern but the amplitude decreased with time compared to intact plants. The results collectively suggest that some, but not all, of the shoot ethylene rhythm depends on the transport of ACC from the roots to the shoots.

Transport of 1-aminocyclopropane-1-carboxylic acid (ACC) in the transpiration stream of tomato (Lycopersicon esculentum) in relation to foliar ethylene production and petiole epinasty

We investigated the concentration and delivery of 1-aminocyclopropane-1-carboxylic acid (ACC) in the transpiration stream of flooded and well-drained 1-month-old tomato plants (Lycopersicon esculentum Mill. cv. Ailsa Craig) over time in parallel with foliar ethylene production and petiole epinasty. ACC was measured by gas chromatography using a nitrogen–phosphorus detector. Before analysis, roots of freshly detopped plants were pressurised pneumatically to make xylem sap flow at rates similar to those of whole plant transpiration. Delivery of ACC from roots to shoots of well-drained plants was sufficient to support basal ethylene production in shoots of unstressed plants. Delivery from flooded, oxygen-deficient, roots increased after 6 h and coincided with the onset of epinastic leaf curvature. Further increases in ACC delivery and epinastic curvature occurred later in the photoperiod. After 24 h flooding, ACC delivery in xylem sap was 28 times more than in well-drained plants. This increased export of ACC from flooded roots was more than sufficient to account for the extra ethylene production in the shoots and coincided with ACC accumulation in the leaves. Removing the shoot before flooding did not reduce ACC export from oxygen-deficient roots indicating that the ACC originated in roots and not the shoot. Increased ethylene production in petioles of flooded plants lagged 18 h behind epinasty.