Application Of AVG Research Articles

Molecular and physiological characterization of the effects of auxin-enriched rootstock on grafting

sGrafting is a highly useful technique, and its success largely depends on graft union formation. In this study, we found that root-specific expression of the auxin biosynthetic gene iaaM in tobacco, when used as rootstock, resulted in more rapid callus formation and faster graft healing. However, overexpression of the auxin-inactivating iaaL gene in rootstocks delayed graft healing. We observed increased endogenous auxin levels and auxin-responsive DR5::GUS expression in scions of WT/iaaM grafts compared with those found in WT/WT grafts, which suggested that auxin is transported upward from rootstock to scion tissues. A transcriptome analysis showed that auxin enhanced graft union formation through increases in the expression of genes involved in graft healing in both rootstock and scion tissues. We also observed that the ethylene biosynthetic gene ACS1 and the ethylene-responsive gene ERF5 were upregulated in both scions and rootstocks of the WT/iaaM grafts. Furthermore, exogenous applications of the ethylene precursor ACC to the junction of WT/WT grafts promoted graft union formation, whereas application of the ethylene biosynthesis inhibitor AVG delayed graft healing in WT/WT grafts, and the observed delay was less pronounced in the WT/iaaM grafts. These results demonstrated that elevated auxin levels in the iaaM rootstock in combination with the increased auxin levels in scions caused by upward transport/diffusion enhanced graft union formation and that ethylene was partially responsible for the effects of auxin on grafting. Our findings showed that grafting success can be enhanced by increasing the auxin levels in rootstocks using transgenic or gene-editing techniques.

EXTENDING THE KHALAL STAGE OF “ZAGHLOUL” DATES BY UTILIZING THE MODIFIED PACKING METHOD AND ANTIETHYLENE COMPOUNDS

The present study was conducted in order to increase the availability of "Zaghloul" dates favored for consumption at the khalal stage. During the two successive seasons 2017 and 2018, dipping postharvest treatments and the modified packing method were applied to extend the khalal stage of "Zaghloul" date palm fruits. The treatments included the control (water), the control with wood shavings, CaCl2 (2%, w/v), glycerol (1 %, v/v), CaCl2 plus glycerol, AVG (50 ppm), putrescine (2mM) and AVG followed by putrescine, then, the treated fruits with the substances treatments were embedded in layers of the wood shavings. All packed dates stored under cold storage conditions (4oC and 90 -95 % relative humidity). The results revealed that all treatments were able to reduce weight loss, fruit decay, electrolyte leakage, total soluble solids percentages and rutab score. More drastic reduction in these characteristics was found with the application of AVG when followed by putrescine in the presence of wood shavings. While, there was no clear trend for treatments effect on fruit total acidity content. Treated dates with CaCl2 or AVG when followed by putrescine had the highest values of total sugars. On the contrary, anthocyanin content in dates peel slightly increased by different treatments. This study provided evidence about the feasibility of using the combination of AVG with putrescine or CaCl2 plus glycerol in the presence of wood shavings to extend the khalal stage of "Zaghloul" dates and maintain their quality on a large scale.

Effect of pre-storage ascorbic acid and Aloe vera gel coating application on enzymatic browning and quality of lotus root slices.

The effect of ascorbic acid [AA (1%)] and Aloe vera gel [AVG (50%)] coating alone and in combination was investigated on enzymatic browning and quality of lotus root slices during storage at 20±1°C. The combined application of AA and AVG coating delayed surface browning, reduced increase in relative electrolyte leakage (REL) and showed higher overall visual quality (OVQ). Similarly, AA and AVG combined treatment reduced superoxide anion ( ) and hydrogen peroxide (H2 O2 ) production and malondialdehyde (MDA) content, and suppressed peroxidase (POD) and polyphenol oxidase (PPO) activities. In addition, AA and AVG treatment conserved higher AA content, ascorbate peroxidase (APX), superoxide dismutase (SOD) and catalase (CAT) enzymes activities along with higher total phenolics and radical scavenging activity. In conclusion, the combined application of AA and AVG coating could be an appropriate treatment to delay surface browning and quality loss of lotus root slices. PRACTICAL APPLICATIONS: Lotus root is an aquatic rhizome vegetable. The fresh-cut slices of lotus roots are prone to post-cut enzymatic browning and quality deterioration during postharvest storage. Browning induced loss of visual quality and microbial infestations are the leading constraints in extending storage and/or shelf life of lotus root slices. Surface browning results in loss of characteristic color eventually leading to significant reduction in market potential and visual quality. However, quality deterioration and development of browning could be delayed with some suitable postharvest treatments. So, the effect of AA and Aloe vera gel based coating was investigated for quality conservation of lotus root slices. The findings of the current work are of global importance in reducing browning and conserving visual quality of lotus root slices in particular and fresh-cut produce in general.

Influence of 1-aminoethoxyvinylglycine hydrochloride and α-naphthalene acetic acid on fruit retention, quality, evolved ethylene, and respiration in apples

Effects of 1-aminoethoxyvinylglycine hydrochloride (AVG or Aviglycine HCl or ReTain) and αnaphthalene acetic acid (NAA) on fruit retention, fruit quality, eveloved ethylene, and respiration in ‘Rome Beauty’ and three ‘Delicious’ apple cultivars (Malus domestica Borkh.) were studied. The experimental trees were treated with either AVG, applied at 120 g a.i. per 935 L . ha -1 or NAA, applied at the rate of 10 ppm at 1870 L . ha -1 . The AVG treatment was applied four weeks before anticipated harvest date while the NAA treatment was applied 7 days before harvest. In both 'Delicious' and 'Rome' apples, application of AVG maintained fruit retention and firmness but reduced starch hydrolysis, ethylene evolution, and respiration as compared to the NAA treatment. In the later harvests, fruit weights in NAA-treated trees were slightly higher than those treated with AVG. Fruit retention, maturity and quality differences between AVG and NAA treatments were more pronounced as the time past from the commercial harvest dates. Based on this study, application of AVG is more effective than NAA in preventing fruit drop and delaying fruit maturity and thus storage life of apples.

Ethylene is involved in leafy mustard systemic resistance to Turnip mosaic virus infection through the mitochondrial alternative oxidase pathway

The role of the mitochondrial alternative oxidase (AOX) pathway and the relationship between AOX and ethylene in resistance to Turnip mosaic virus (TuMV) were investigated in systemic infected mustard leaves. Expressions of AOX1a and ethylene biosynthesis-related genes were enhanced in the upper uninoculated leaves at 6 days of postinoculation (dpi). Increased accumulation of AOX1a transcript and reduced levels of TuMV-CP were also observed after pretreatment with AA (a cytochrome pathway inhibitor) or ACC (an ethylene precursor) at non-lethal concentrations. Meanwhile, application of AVG (an ethylene biosynthesis inhibitor) mostly blocked TuMV-induced AOX activity and substantially increased TuMV susceptibility in the upper leaves. SHAM (AOX pathway inhibitor) pretreatment partially reduced the ACC-induced cyanide-resistant respiration and TuMV resistance. Conversely, AA and SHAM pretreatments had little effect on generation of ethylene. These results suggested that the TuMV-induced increase of AOX was partly involved in the ethylene pathway, and ethylene unregulated AOX in upper uninoculated mustard leaves.

Maturação e qualidade pós-colheita de ameixas 'laetitia' com a aplicação pré-colheita de AVG e GA3

O objetivo deste trabalho foi avaliar o efeito da aplicação pré-colheita de aminoetoxivinilglicina (AVG; 0; 90; 125 mg L-1) e ácido giberélico (GA3; 0 e 100 mg L-1) sobre a maturação e a qualidade de ameixas 'Laetitia' após o armazenamento refrigerado. Foi utilizado o delineamento em blocos casualizados, com seis tratamentos (três doses de AVG x duas doses de GA3) e quatro repetições. A aplicação do GA3 e do AVG foi realizada 28 e 7 dias antes do início da primeira colheita, respectivamente. O experimento foi conduzido em 2007 e em 2009. Em cada ano foram realizadas três colheitas, sendo 11-01-2007, 17-01-2007 e 25-01-2007 (colheita comercial); 15-01-2009, 22-01-2009 (colheita comercial), e 29-01-2009. Em 2007, frutos da terceira colheita foram armazenados em uma câmara fria comercial durante 22 dias, a 0,5ºC, e umidade relativa de 92% e mais cinco dias de exposição em condição ambiente (temperatura média de 23ºC e umidade relativa média de 60%). A aplicação pré-colheita de AVG (125 mg L-1), isoladamente ou GA3, ou GA3 + AVG, retarda a maturação de ameixas 'Laetitia' na planta. O tratamento pré-colheita de ameixas 'Laetitia' com GA3, seguido da aplicação de AVG, manteve maior firmeza da polpa dos frutos após o armazenamento refrigerado.

Effects of Foliar‐Applied Ethylene Inhibitor and Synthetic Cytokinin on Creeping Bentgrass to Enhance Heat Tolerance

ABSTRACTHeat stress is a major factor causing leaf senescence and other physiological damages in cool‐season grass species. Cytokinins and ethylene are two major plant hormones affecting leaf senescence. The objective of this study was to determine whether foliar application of an ethylene synthesis inhibitor (aminoethoxyvinylglycine, AVG) and a synthetic cytokinin (trans‐zeatin riboside, t‐ZR) would enhance creeping bentgrass (Agrostis stolonifera L.) tolerance to heat stress associated with the suppression of leaf senescence. Creeping bentgrass ‘Penncross’ was exposed to either heat stress (35°C) or optimal growth temperature (20°C) for 35 d in growth chambers. Plants at each temperature were treated with 25 μM AVG, 25 μM t‐ZR or water (control). Foliar spray of AVG or zeatin riboside (ZR) solution resulted in increases in turf quality, leaf chlorophyll content, activities of antioxidant enzymes, and the reduction in lipid peroxidation, compared with water‐treated plants, for plants exposed to heat stress. In addition, foliar application of AVG suppressed ethylene evolution, whereas exogenous ZR resulted in elevated endogenous cytokinin levels under heat stress. The results suggest that the application of AVG or ZR suppressed leaf senescence and improved heat tolerance of creeping bentgrass, which could be because of their effects on endogenous production of ethylene and cytokinins and on antioxidant metabolism.

Ethylene Is Not Involved in Hormone- and Bromoethane-Induced Dormancy Break in Russet Burbank Minitubers

The involvement of ethylene in the dormancy breaking actions of cytokinins, GA, and BE was investigated using Russet Burbank minitubers. Injection of 10 µg tuber−1 BA, CP, GA, NG, or ZEA or 24 hour exposure to BE effectively broke dormancy and stimulated sprout growth over a two-week period. Although ethylene production was slightly enhanced by all treatments, a significant increase in ethylene production was observed in minitubers treated with BE, CP, or NG. Pretreatment with the ethylene antagonists STS or MCP did not affect the dormancy breaking actions of any of the agents tested. Application of the ethylene synthesis inhibitor AVG to NG-treated minitubers, completely suppressed ethylene production but had no effect on dormancy break. Application of exogenous ethylene or stimulation of endogenous ethylene production by ACC treatment did not break minituber dormancy or stimulate sprout growth. Collectively, these results indicate that endogenous ethylene does not play a role in the dormancy breaking actions of cytokinins, GA, or BE.

Qualidade da maçã "Gala" armazenada em atmosfera controlada associada à absorção e ao controle da síntese e da ação do etileno

Este trabalho teve por objetivo avaliar o efeito da inibição da biossíntese de etileno no período pré-colheita e o efeito da inibição da ação ou da absorção do etileno durante o armazenamento em atmosfera controlada (AC; 1,2kPa de O2 + 2,5kPa de CO2 a 0°C) sobre a qualidade de maçãs cv. "Gala". Além disso, avaliou-se também o efeito combinado desses tratamentos. Os tratamentos avaliados foram: (1) armazenamento em AC (controle); (2) aplicação pré-colheita de AVG; (3) AVG + aplicação pós-colheita de 1-MCP; (4) aplicação de 1-MCP; (5) AVG + absorção do etileno durante todo o período de armazenamento; e (6) absorção de etileno. Após oito meses de armazenamento mais sete dias a 20°C, os frutos tratados com AVG apresentaram menor atividade da ACC oxidase. A combinação de AVG + 1-MCP ou AVG + absorção de etileno mantiveram menor produção de etileno até cinco dias de vida de prateleira a 20°C. Além disso, a firmeza da polpa dos frutos submetidos a esses tratamentos combinados manteve-se mais elevada. A cor de fundo da epiderme manteve-se mais verde nos frutos tratados com AVG, independente do tratamento em pós-colheita, demonstrando que a modificação da coloração da epiderme é mais afetada pelo etileno produzido ainda na pré-colheita. Portanto, conclui-se que a aplicação em pré-colheita de AVG associada com a absorção do etileno durante o armazenamento é mais eficiente no controle da maturação de maçãs "Gala", no entanto, a aplicação pré-colheita de AVG combinada com a aplicação pós-colheita de 1-MCP também é eficiente.

Effects of the Bioregulators Aminoethoxyvinylglycine and Ethephon on Brix, Carbohydrate, Acid, and Mineral Concentrations in 'Scarletspur Delicious' Apple Juice

In a study conducted over three crop seasons, Ethrel (ETH) increased the Brix, sucrose, and sorbitol content of 'Scarletspur Delicious' apple juice while reducing the fructose content. Both longer preharvest exposure to, and higher concentrations of, ETH had a stronger influence than application closer to harvest and/or at lesser amounts. Time of ETH application tended to influence individual carbohydrates more so than amount of ETH applied. ETH reduced total acidity and also reduced apple juice individual acid (quinic and malic) contents with longer preharvest exposure or higher concentrations. Aminoethoxyvinylglycine [AVG (ReTain)] reduced both Brix and sucrose content of 'Scarletspur Delicious' apple juice, but had no influence on either total acidity or individual acid contents. Combinations of AVG with ETH tended to counteract the influence of either used alone on total Brix, carbohydrates, total acidity and individual acids. Mineral content of 'Scarletspur Delicious' apple juice was not strongly influenced by application of either ETH or AVG.

Ethylene evolution, H 2O 2 scavenging enzymes and membrane integrity of Cicer arietinum L. nodules as affected by nitrate and aminoethoxyvinylglycine

Summary Nitrate induced changes on ethylene evolution, H 2 O 2 scavenging enzymes and membrane integrity in chickpea ( Cicer arietinum L.) cv. HC-1 nodules were studied under green house conditions. Plants were exposed to 10, 20 and 40 mmol/L NO − 3 at vegetative stage (40-45 DAS). Aminoethoxyvinyl-glycine (5 μmol/L, AVG) was added to nodules 24 h after NO − 3 treatment. An increase in ethylene evolution (388 % to 832 %) was noticed 3 d later in NO − 3 treated nodules. However, this declined 58-69 % with addition of AVG. The H 2 O 2 scavenging enzyme i.e. catalase (EC 1.11.1.6), peroxidase (EC 1.11.1.7), ascorbate peroxidase (EC 1.11.1.11) and glutathione reductase (EC 1.11.1.9) increased by 9-27 %, 155-227 %, 33-117 % and 53-109 %, respectively. Despite the increase in the activity of these enzymes H 2 O 2 content increased by 116 to 168 %. Superoxide dismutase (EC 1.15.1.1) decreased from 32 % to 63 % with NO − 3 . Application of AVG to NO − 3 treated nodules also showed a decline in activity of catalase (16-23 %), peroxidase (21-30 %), ascorbate peroxidase (25-49 %) and glutathione reductase (46-53 %) with simultaneous depletion of H 2 O 2 content (29-34 %). Lipid peroxidation and electrolyte leakage increased 5-9 fold and 2-4 fold, respectively. However, these effects were also overcome to some extent by added AVG, showing a reversible loss in membrane integrity. It is concluded that ethylene production is increased in nodules on NO − 3 application. H 2 O 2 content increased significantly even on the activation of H 2 O 2 scavenging enzymes. The membrane integrity was adversely affected. AVG treatment showed partial recovery in above parameters showing the involvement of ethylene directly or indirectly in the functioning of nodules on NO − 3 application.

Effect of ethylene on Agrobacterium tumefaciens‐mediated gene transfer to melon

AbstractThe effect of ethylene on gene transfer mediated by an Agrobacterium tumefaciens harbouring a binary vector with the β‐glucuronidase (uid A) gene was investigated in melon, Cucumis melo L. Explants excised from melon cotyledons produced ethylene, the production of which was increased by the addition of 1‐aminocyclopropane‐1‐carboxylic acid (ACC, 20 or 200 μM), and inhibited by the addition of aminoethoxy‐vinylglycin (AVG, 10 μM). Agrobacterium inoculation of explants increased ethylene production, while application of AVG during inoculation reduced it. After 4 days of co‐cultivation with Agrobacterium, gene transfer in the explants was assayed by transient uid A expression. Application of ACC to the co‐cultivation medium reduced Agrobacterium‐mediated gene transfer to explants and that of AVG increased it. These results suggest that ethylene affects the A. tumefaciens‐mediated gene transfer to the explants excised from melon cotyledons, and the efficiency of Agrobacterium‐mediated gene transfer can be improved by inhibiting ethylene production from the explants.

Role of ethylene in senescence of watercress leaves

Detached watercress leaves showed a rapid senescence rate as compared with other herbs. It was therefore of interest to investigate the role of ethylene in the rapid senescence of watercress leaves, and So estimate the efficacy of various inhibitors of elhylene synthesis (aminoethoxyvinylglycine, AVG) and action (CO2, Ag+) in retarding senescence processes. The progress of senescence in watercress bunches (leaves attached to cut stems) and in detached leaves was estimated by measuring the rate of chlorophyll (Chl) loss, proteolysis and lipid oxidation. Evidence is presented showing that application of 11% CO2 to watercress bunches in a flow‐through system had a long‐lasting effect on senescence, exhibited by highly efficient retardation of all the senescence processes tested. On the other hand, application of AVG (O.1 mM) or Ag‐(30 μM) to detached leaves affected Chl loss much more than prciteolysis. These results suggest that the senescence‐retarding activity of CO2 cannot be attributed solely to its action as an anli‐ethylene agent and that not all senescence‐associated processes are regulated by ethylene.

Staminate Floral Induction on Gynoecious Buffalo Gourd Following Application of AVG

Abstract Application of AVG to the terminal meristematic region of gynoecious buffalo gourd (Cucurbita foetidissima HBK.) vines resulted consistently in the induction of staminate floral buds. Linear models adequately described the regressions of staminate floral induction frequency on AVG concentration and on frequency of AVG application. If AVG was applied repeatedly on gynoecious plants prior to the onset of female flowering, the transition to the potentially mixed floral phase was delayed. Chemcial name used: [S(E)]-2-amino-4-(2-aminoethoxy)-3-butyric acid (AVG).