Accumulation Of 1-aminocyclopropane-1-carboxylic Acid Research Articles

Hydrogen sulfide delays softening of banana fruit by inhibiting cell wall polysaccharides disassembly

SummaryHarvested banana undergoes rapid softening, which limits its shelf life. To delay softening, banana fruit was treated with hydrogen sulfide (H2S) emitted by 0.6 mm sodium hydrosulfide (NaHS) and stored at 15 °C for 16 days. The effects of H2S on cell wall degradation and other physiological characteristics were investigated. In comparison to control fruits, H2S‐treated bananas retained a higher level of fruit firmness, but lower hue values. Ethylene metabolism analysis suggested that H2S inhibited the production of ethylene and the accumulation of 1‐aminocyclopropane‐1‐carboxylic acid (ACC) and decreased the activities of ACC synthase (ACS) and ACC oxidase (ACO). Cell wall polysaccharides determination assays suggested that H2S treatment increased the proportion of HCl‐soluble pectin (HSP), NaOH‐soluble pectin (NSP), cellulose and hemicellulose but decreased water‐soluble pectin (WSP) in fruits. H2S treatment also inhibited the activities of polysaccharide degrading enzymes such as polygalacturonase (PG), pectin methylesterase (PME), pectin lyase (PL), cellulase (CL) and β‐galactosidase (β‐Gal). Transmission electron microscopy analysis suggested that H2S protected cell walls from structural breakdown. These results indicated that H2S is effective in delaying banana softening by regulating cell wall polysaccharide metabolism.

Targeted system approach to ethylene biosynthesis and signaling of a heat tolerant tomato cultivar; the impact of growing season on fruit ripening.

Growing tomato in hot weather conditions is challenging for fruit production and yield. Tomato cv. Savior is a heat-tolerant cultivar which can be grown during both the Vietnamese winter (mild condition) and summer (hot condition) season. Understanding the mechanisms of ethylene biosynthesis and signaling are important for agriculture, as manipulation of these pathways can lead to improvements in crop yield, stress tolerance, and fruit ripening. The objective of this study was to investigate an overview of ethylene biosynthesis and signaling from target genes to proteins and metabolites and the impact of growing season on a heat tolerant tomato cultivar throughout fruit ripening and postharvest storage. This work also showed the feasibility of absolute protein quantification of ethylene biosynthesis enzymes. Summer fruit showed the delayed peak of ethylene production until the red ripe stage. The difference in postharvest ethylene production between winter and summer fruit appears to be regulated by the difference in accumulation of 1-aminocyclopropane-1-carboxylic acid (ACC) which depends on the putative up-regulation of SAM levels. The lack of differences in protein concentrations between winter and summer fruit indicate that heat stress did not alter the ethylene biosynthesis-related protein abundance in heat tolerant cultivar. The analysis results of enzymatic activity and proteomics showed that in both winter and summer fruit, the majority of ACO activity could be mainly contributed to the abundance of ACO5 and ACO6 isoforms, rather than ACO1. Likewise, ethylene signal transduction was largely controlled by the abundance of ethylene receptors ETR1, ETR3, ETR6, and ETR7 together with the constitute triple response regulator CTR1 for both winter and summer grown tomatoes. Altogether our results indicate that in the heat tolerant tomato cv. Savior, growing season mainly affects the ethylene biosynthesis pathway and leaves the signaling pathway relatively unaffected.

Effect of exogenous spermine on chilling injury and antioxidant defense system of immature vegetable soybean during cold storage.

The effect of exogenous spermine on chilling injury (CI) and antioxidant defense system of immature vegetable soybean (Glycine max L.) during cold storage were investigated. Freshly harvested immature soybeans were treated with 0.8mmol/L spermine at room temperature for 20min and then stored at 5 ± 1°C or 1 ± 1°C and 85-95% relative humidity for up to 60days. Results showed that exogenous spermine alleviated the CI, delayed the gradual decreasing activities of superoxide dismutase (SOD) and catalase, and maintained a favourable balance in reactive oxygen species levels at storage period. Although cold temperature (1 ± 1°C) inhibited the synthesis of l-(malonylamino)-cyclopropane-l-carboxylic acid (MACC), raised ethylene production, and resulted in membrane damage, exogenous spermine obviously hindered the accumulation of 1-aminocyclopropane-1-carboxylic acid (ACC). It was concluded that exogenous spermine alleviated CI of cold-stored immature soybeans through regulating the antioxidant system and ACC metabolism.

Mode of action of abscisic acid in triggering ethylene biosynthesis and softening during ripening in mango fruit

The role of abscisic acid (ABA) in triggering ethylene biosynthesis and ripening of mango fruit was investigated by applying ABA [S-(+)-cis,trans-abscisic acid] and an inhibitor of its biosynthesis [nordihydroguaiaretic acid (NDGA)]. Application of 1mM ABA accelerated ethylene biosynthesis through promoting the activities of ethylene biosynthesis enzymes (1-aminocyclopropane-1-carboxylic acid synthase, ACS; 1-aminocyclopropane-1-carboxylic acid oxidase, ACO) and accumulation of 1-aminocyclopropane-1-carboxylic acid (ACC), enhanced fruit softening and activity of endo-polygalacturonase and reduced pectin esterase activity in the pulp. The activities of ethylene biosynthesis and softening enzymes were significantly delayed and/or suppressed in the pulp of NDGA-treated fruit. The ABA-treated fruit had higher total sugars and sucrose as well as degradation of total organic acids, and citric and fumaric acids compared with NDGA treatment. These results suggest that ABA is involved in regulating mango fruit ripening and its effects are, at least in part, mediated by changes in ethylene production.

1‐MCP suppresses ethylene biosynthesis and delays softening of ‘Hami’ melon during storage at ambient temperature

'Hami' melon is susceptible to softening during postharvest storage at ambient temperature, which enhances postharvest deterioration and limits transportation and storage. To look for a method of softening control, the effect of 1-methylcyclopropene (1-MCP) on regulating postharvest softening of 'Hami' melon fruit was investigated. 1-MCP treatment at 1 µL L(-1) significantly reduced ethylene production and maintained higher levels of fruit firmness. It also markedly inhibited the accumulation of 1-aminocyclopropane-1-carboxylic acid (ACC) and maintained lower activities of ACC synthase and ACC oxidase. In addition, 1-MCP treatment reduced the activities of fruit-softening enzymes such as pectin methyl esterase, polygalacturonase, endo-1,4-β-glucanase and β-galactosidase. 1-MCP was effective in suppressing ethylene production and delaying fruit softening in 'Hami' melon by decreasing the activities of ethylene biosynthesis enzymes and inhibiting fruit-softening enzymes.

OsEDR1 negatively regulates rice bacterial resistance via activation of ethylene biosynthesis

Rice OsEDR1 is a sequence ortholog of Arabidopsis EDR1. However, its molecular function is unknown. We show here that OsEDR1-suppressing/knockout (KO) plants, which developed spontaneous lesions on the leaves, have enhanced resistance to Xanthomonas oryzae pv. oryzae (Xoo) causing bacterial blight disease. This resistance was associated with increased accumulation of salicylic acid (SA) and jasmonic acid (JA), induced expression of SA- and JA-related genes and suppressed accumulation of 1-aminocyclopropane-1-carboxylic acid (ACC), the direct precursor of ethylene, and expression of ethylene-related genes. OsEDR1-KO plants also showed suppressed production of ethylene. Knockout of OsEDR1 suppressed the ACC synthase (ACS) gene family, which encodes the rate-limiting enzymes of ethylene biosynthesis by catalysing the formation of ACC. The lesion phenotype and enhanced bacterial resistance of the OsEDR1-KO plants was partly complemented by the treatment with ACC. ACC treatment was associated with decreased SA and JA biosynthesis in OsEDR1-KO plants. In contrast, aminoethoxyvinylglycine, the inhibitor of ethylene biosynthesis, promoted expression of SA and JA synthesis-related genes in OsEDR1-KO plants. These results suggest that ethylene is a negative signalling molecule in rice bacterial resistance. In the rice-Xoo interaction, OsEDR1 transcriptionally promotes the synthesis of ethylene that, in turn, suppresses SA- and JA-associated defence signalling.

Effect of methylglyoxal bis-(guanylhydrazone) on polyamine and ethylene biosynthesis of apple fruit after harvest

Polyamine and ethylene both play important roles in fruit ripening, whose biosynthetic pathways share a common substrate, S-adenosylmethionine (SAM). To unravel the interrelationship between polyamine and ethylene, their metabolism and expression of relevant genes were investigated in apple fruit (Malus domestica Borkh.) treated with methylglyoxal bis-(guanylhydrazone) (MGBG). The MGBG-treated fruit had higher ethylene production until 16 days after treatment (DAT) with preceding accumulation of 1-aminocyclopropane-1-carboxylic acid (ACC) than control fruit and then decreased to nearly the same level as control. Ethylene promotion at the early stage by MGBG was accompanied by increased expression of apple ACCsynthase (Md-ACS1) and ACC oxidase (MdACO). The expression of apple SAM synthase (MdSAMS) in MGBG-treated fruit was slightly higher than that in control. On the other hand, significant changes in free polyamine titers were observed at some stages, but the changes did not show consistent trends. Based on these observations, possible relationship between polyamine and ethylene pathways was discussed.

Expression of 1-Aminocyclopropane-1-Carboxylate Synthase and 1-Aminocyclopropane-1-Carboxylate Oxidase Genes during Ripening in ‘Rendaiji’ Persimmon Fruit

‘Rendaiji’ persimmon (Diospyros kaki Thunb.) is a pollination variant astringent type persimmon that is characterized by low levels of the ethylene production rate during ripening. However, a serious problem in postharvest handling is that mature fruits soften quite rapidly accompanied with increased ethylene production after treatments to remove astringency. In this study, we investigated changes in ethylene biosynthesis, by following the accumulation of 1-aminocyclopropane-1-carboxylic acid (ACC) and 1-(malonylamino)-cyclopropane-1-carboxylic acid (MACC), as well as ACC synthase (ACS) and ACC oxidase (ACO) activities and the expression of their respective genes in relation to the process and mechanism of fruit ripening. The response by persimmon fruits to 1-methylcyclopropene (1-MCP) treatments during postharvest ripening was also studied. Ripening was accompanied by relatively low levels of the ethylene production rate, concomitant with a decrease in firmness, especially after exposure to a deastringency treatment by using ethanol vapor. Postharvest application of 1-MCP, on the other hand, did not suppress ethylene production rates to the expected level, but it lowered the accumulation of ACC and the activities of ACC synthase and ACC oxidase. However, the degree of inhibition was higher in ACC synthase, which would imply that the step catalyzed by this enzyme is more subject to regulation by ethylene in this fruit. Comparing gene expression patterns in control and 1-MCP treated fruit by using quantitative RT (Real-Time)-PCR showed that ethylene biosynthesis associated with rapid ripening in ‘Rendaiji’ was accompanied by the expression of DK-ACS1, DK-ACS2, DK-ACO1, and DK-ACO2 genes. The expression of DK-ACS3, however, was not induced.

Water stress-induced ethylene in the calyx triggers autocatalytic ethylene production and fruit softening in ‘Tonewase’ persimmon grown in a heated plastic-house

‘Tonewase’ Japanese persimmon fruit (Diospyros kaki Thunb.) grown in a heated plastic-house softens rapidly within several days of harvest, which is a major problem in marketing of this cultivar. In this study, we elucidated the involvement of water stress-induced ethylene in fruit softening and investigated the induction mechanism of this ethylene biosynthesis occurring in specific tissues at the molecular level. Two instances of increase in ethylene production were observed in fruit held in ambient low humidity conditions (40–60% RH), an initial increase on the 1st and 2nd days and a second increase on the 6th and 8th days after harvest. Increase in ethylene production was accompanied by rapid softening in these fruit. Fruit held in high humidity conditions (>95%) neither produced detectable levels of ethylene nor softened rapidly. Moreover, treatment of the fruit held in low humidity with 1-methylcyclopropene (1-MCP), a strong inhibitor of ethylene action, inhibited fruit softening remarkably. These results suggest the involvement of water stress-induced ethylene in fruit softening. 1-MCP also suppressed the second increase in ethylene production but not the initial increase, indicating that the initial increase is induced directly in response to the primary water stress signal while the second is induced autocatalytically by the ethylene produced during the initial phase. During the initial increase in ethylene, the calyx produced more than 5 nl g−1 h−1 of ethylene accompanied by increased accumulation of 1-aminocyclopropane-1-carboxylic acid (ACC) and expression of DK-ACS2. In pulp, 0.5 nl g−1 h−1 of ethylene was detected but no increase in ACC content or expression of any ethylene biosynthetic genes was observed. During the second increase in ethylene, ethylene production in the calyx was not detected whereas the pulp produced 0.2–0.4 nl g−1 h−1 of ethylene with a marked increase in ACC content and expression of the two ACC synthase (DK-ACS1, DK-ACS2) and one ACC oxidase (DK-ACO1) genes. These results suggest that in plastic-house ‘Tonewase’ persimmon fruit, ethylene production is initiated in the calyx in response to water stress through activated expression of DK-ACS2, and this ethylene in turn induces autocatalytic ethylene production in the pulp. As the flesh firmness decreased markedly just after the initial ethylene production, the results also indicate that the fruit softening is due to the action of ethylene produced in the calyx.

Ethylene production and ACC‐accumulation in Agrobacterium tumefaciens‐induced plant tumours and their impact on tumour and host stem structure and function

ABSTRACTEthylene emission from wild‐type Agrobacterium tumefaciens (C58)‐induced stem tumours of Ricinus communis was continuously measured with two different methods, process gas chromatography and photo‐acoustic spectrometry. Ethylene production was as high as 700 pmol g FW–1 h–1, namely 140 times greater than emitted by non‐tumourized control stems. It was highest in 5‐week‐old tumours, independent of light, depressed by anoxia and, during water deficit it was stimulated by rewatering. A remarkable concomitant CO‐production was discovered. Accumulation of 1‐aminocyclopropane‐1‐carboxylic acid (ACC), the substrate of ACC‐oxidase, preceded ethylene emission with a maximum 2 weeks after tumour induction. Simultaneously, the xylem in the tumour‐adjacent host stem underwent drastic changes: it increased two to three times in thickness, vessel diameters decreased, the rays remained unlignified and became multiseriate. With increasing emission of ethylene aerenchyma developed in the non‐transformed, tumour‐surrounding tissue that formerly was stem cortex. Cotyledons reacted with epinastic symptoms indicating induction of senescence. The present results reveal an important role of ethylene, in addition to cytokinin and auxin, for the differentiation and physiology of A. tumefaciens‐induced tumours.

Accumulation of 1-Aminocyclopropane-1-carboxylic acid (ACC) in Petunia Pollen is Associated with Expression of a Pollen-specific ACC Synthase Late in Development

Mature pollen from Petunia hybrida contains significant levels of 1-aminocyclopropane-1-carboxylic acid (ACC), and this ACC is thought to play a role in pollination-induced ethylene by the pistil. We investigated the developmental accumulation of ACC in anthers and pollen. The level of ACC in anthers was very low until the day before anthesis, at which time it increased 100-fold. A 1.1-kb partial ACC synthase cDNA clone (pPHACS2) was amplified from total RNA isolated from mature anthers by reverse transcriptase, followed by polymerase chain reaction using oligonucleotide primers synthesized to conserved amino acid sequences in ACC synthases. The expression of pPHACS2 mRNA during anther development was correlated with the accumulation of ACC and was localized to the pollen grain. The pPHACS2 cDNA was used to identify the PH-ACS2 gene from a library of genomic DNA fragments from Petunia hybrida. PH-ACS2 encoded an ACC synthase transcript of four exons interrupted by three introns. The ACC synthase protein encoded by the PH-ACS2 gene shared >80% homology with ACC synthases from tomato (LE-ACS3) and potato (ST-ACS1a). A chimeric PH-ACS2 promoter-β-glucuronidase (GUS) gene was used to transform petunia and transgenic plants were analyzed for GUS activity. GUS staining was localized to mature pollen grains and was not detected in other tissues. Despite similarities to LE-ACS3, we did not detect GUS activity under conditions of anaerobic stress or in response to auxin. A series of 5-prime-flanking DNA deletions revealed that sequences within the PH-ACS2 promoter were responsible for pollen-specific expression.

Induction of ethylene biosynthesis in Nicotiana tabacum by a Trichoderma viride xylanase is correlated to the accumulation of 1-aminocyclopropane-1-carboxylic acid (ACC) synthase and ACC oxidase transcripts.

Xylanase (EIX) from the fungus Trichoderma viride elicits ethylene biosynthesis in leaf tissues of Nicotiana tabacum cv Xanthi but not in cv Hicks. The increase in ethylene biosynthesis is accompanied by an accumulation of 1-aminocyclopropane-1-carboxylic acid (ACC), an increase in extractable ACC synthase activity, and increases in ACC synthase and ACC oxidase transcripts. Priming of increases in ACC synthase and ACC oxidase transcripts. Priming of leaves with ethylene (120 microL/L, 14 h) sensitizes the tissue, resulting in an enhanced response to EIX and increases in both the in vivo ACC oxidase activity and ACC oxidase transcript level. EIX and ethylene independently induce ACC oxidase. Inhibition of ethylene biosynthesis by aminoethoxyvinylglycine is not accompanied by a reduction in ACC oxidase transcript level, indicating that ethylene biosynthesis is not required. In contrast to the differential induction of ethylene biosynthesis by EIX in Xanthi versus Hicks cultivars, both cultivars respond to a chemical stress (induced by CuSO4) by enhancing ethylene production. This induction is accompanied by an increase in ACC synthase transcript but not in that of ACC oxidase.

Formation of stress ethylene depends both on ACC synthesis and on the activity of free radical‐generating system

Leaves of soybean (Glyxine max. L., var. Progress) were subjected to desiccation, which brought about varying degree of membrane damage as checked with the conductivity method. Progress of injury up to 30% was associated with promotion of ethylene synthesis and with accumulation of 1‐aminocyclopropane‐1‐carboxylic acid (ACC) and 1‐(malonylamino)cyclopropane‐l‐carboxylic acid (MACC) in the cells, as well as with activation of lipoxygenase, the enzyme which is involved in lipid peroxidation and which is capable of forming activated oxygen. The stress‐induced promotion of ethylene synthesis was inhibited by the ACC synthase inhibitor aminooxyacetate (AOA). as well as by n‐propyl gallate (PG), a free radical scavenger and inhibitor of lipoxygenase. Pretreatment of non‐stressed soybean leaves with different concentrations of PG also resulted in the corresponding inhibition of lipoxygenase activity and ethylene formation, the former effect being less pronounced than the latter one. In the tissues pretreated with propyl gallate, the ACC level was not affected, whereas the MACC substantially increased. In leaves showing 40% membrane damage neither lipoxygenase activity nor ethylene synthesis increased any further, despite a further increase in the ACC and MACC levels. Therefore, we propose that there are two prerequisites for effective in vivo synthesis of stress ethylene: promotion of ACC synthesis and activation of a free radical‐generating system, which is responsible for the non‐enzymatic conversion of ACC to ethylene. The latter effect seems to be due to the activation of the membrane‐associated lipoxygenase, which depends on stress‐induced alterations in membrane properties.