Application Of ACC Research Articles

Responses of Ethylene Emission, Abscission, and Fruit Quality to the Application of ACC as a Chemical Thinner in ‘Flatbeauti’ Peach

Peach (Prunus persica (L.) Batsch) trees are prone to heavy cropping, but crop load management options are limited. 1-aminocyclopropane-1-carboxylic acid (ACC) has been suggested to reduce crop load and improve fruit quality in peaches, but many questions remain concerning the role of endogenous ethylene in the abscission response and other side effects. Here, the use of ACC as a chemical thinner in peach trees was studied at different rates (350, 500, and 750 mg L−1) and timings [at full bloom (FB) and after petal fall (AP) when the fruit was approximately 15–20 mm in diameter] by comparing the results to those of an untreated control and a hand-thinning treatment as a reference. The abscission response and ethylene emission were related to the ACC concentration. ACC-induced ethylene production, as well as some degree of defoliation, was time-dependent, with the highest ethylene emission peaks and the lowest defoliation degree occurring when ACC was applied at FB. On the other hand, the intra-annual differences in the abscission response between the FBs and APs varied depending on the season. AP-treated fruits produced more endogenous ethylene than did untreated fruits up to harvest, which could have influenced fruit color. Finally, our results indicate that ACC in the range of 500 and 350 mg L−1 can be used in ‘Flatbeauti’ peaches at FB and AP, respectively, to induce adequate levels of fruit crop load without or with minor undesired effects.

Turkish speech-language therapists' perceptions and experiences of augmentative and alternative communication

Objectives: In this study, it is aimed to reveal what extent speech and language therapists (SLT) working in Turkey used augmentative and alternative communication (AAC) systems in their working area. For this purpose, it was investigated how they perceive AAC in terms of its scope and role; ACC applications within the scope of interventions for communication, language and speech disorders; best practice insights on AAC; what factors are seen as facilitating or limiting the implementation of AAC within the scope of intervention and suggestions for providing the best practice for AAC. Methods: Phenomenology, one of the qualitative research methods, was used in the study. The subject of the study is the opinions of SLTs working in Turkey on their clinical practices and thoughts on the use of AAC. The study group consists of 15 SLTs from Turkey and determined by using maximum diversity sampling method. The semi-structured interview forms were used in which SLTs’ views, suggestions and expectations about AAC applications in the service delivery as a data collection tool. The obstacles and difficulties in these applications were discussed. Content analysis was used and also carried out using the qualitative data analysis program MAXQDA 2018. In order to ensure the consistency of the data analysis, the data were analyzed by another field expert and the 92% consensus was tried to be reached by using the consistency formula. Results: Participant opinions consist of benefiting status from AAC, opinions on the importance of AAC, preferred case groups and reasons for AAC implementation, opinions on current best practice understanding on communication and language intervention/use of AAC, opinions on current working conditions on AAC practices, opinions on the limitations of the use of AAC in communication and language intervention and recommendations for ensuring effective use of AAC themes. Conclusions: The results of the study show that supporting individuals who can benefit from AAC in the context of intervention services for communication disorders requires great effort. In addition, SLTs stated that they strongly believed in AAC and its potential value for individuals with communication disorders, but did not have sufficient self-confidence about their current or developing skills in this area. It is also seen that clinicians need training and support from employers, professional or government agencies that set policies and standards to achieve their AAC related goals.

A very-long-chain fatty acid synthesis gene, SD38, influences plant height by activating ethylene biosynthesis in rice.

As an important trait in crop breeding, plant height is associated with lodging resistance and yield. With the identification and cloning of several semi-dwarfing genes, increasing numbers of semi-dwarf cultivars have emerged, which has led to a 'green revolution' in rice (Oryza sativa) production. In this study, we identified a rice semi-dwarf mutant, semi-dwarf 38 (sd38), which showed significantly reduced cell length. SD38 encodes a fatty acid elongase, β-ketoacyl-CoA synthase, which is involved in the synthesis of very-long-chain fatty acids (VLCFAs). Expression analysis showed that SD38 was localized on the membrane of the endoplasmic reticulum, and was expressed in all analyzed tissues with differential abundance. The mutation of SD38 affected lipid metabolism in the sd38 mutant. A functional complementarity test in Saccharomyces cerevisiae indicated that SD38 was capable of complementing the deficiency of ELO3p activity in BY4741-elo3 knockout yeast cells by participating in the synthesis of C24:0 VLCFA. Significant changes were observed in the expression of genes involved in ethylene synthesis, which resulted in reduced content of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) in the sd38 mutant. Exogenously supplied VLCFA (C24:0) increased the expression levels of OsACS3, OsACS4, and OsACO7 and the plant height of sd38 mutant seedlings, similar to the effect of exogenous application of ACC and ethephon. These results reveal a relationship among VLCFAs, ethylene biosynthesis, and plant height and improve our understanding of plant height development in crops.

Effect of 1-aminocyclopropane-1-carboxylic acid accumulation on Verticillium dahliae infection of upland cotton

BackgroundVerticillium wilt of cotton is a serious disease caused by the infection of soil borne fungus Verticillium dahliae Kleb, and the infection mechanisms may involve the regulation of phytohormone ethylene. The precursor of ethylene biosynthesis is 1-aminocyclopropane-1-carboxylic acid (ACC), whose biosynthesis in vivo depends on activation of ACC synthase (ACS). Here, we investigated how ACS activation and ACC accumulation affected the infection of V. dahliae strain Vd991 on cotton (Gossypium hirsutum L.) cultivar YZ1.ResultsPreliminary observations indicated that ACC applications reduced the disease incidence, disease index and stem vascular browning by impeding fungal biomass accumulation. Transcriptome and qRT-PCR data disclosed that Vd991 induced GhACS2 and GhACS6 expression. GhACS2- or GhACS6-overexpressing transgenic YZ1 lines were generated, respectively. In a Verticillium disease nursery with about 50 microsclerotia per gram of soil, these ACC-accumulated plants showed decreased disease indexes, stem fungal biomasses and vascular browning. More importantly, these transgenic plants decreased the green fluorescent protein-marked Vd991 colonization and diffusion in root tissues. Further, either ACC treatment or ACC-accumulating cotton plants activated salicylic acid (SA)-dependent resistance responses.ConclusionsThe GhACS2- and GhACS6-dependent ACC accumulations enhanced the resistance of cotton to V. dahliae in a SA-dependent manner, and this lays a foundation for cotton resistance breeding.

Commercial-Scale Use and Influence of 1-aminocyclopropane-1-Carboxylic Acid as a Rescue Thinner on Fruit Set and Early Fruit Growth in Apples

Only a limited number of post-bloom thinners is available for apple (Malus domestica Borkh.) at the present time. The influence of 1-aminocyclopropane-1-carboxylic acid (ACC) in two strains of ‘Gala’, one strain of ‘Delicious’, and one strain of ‘Fuji’ apples, when fruitlet diameter was about 20 mm, on fruit set and fruit size at hand-thinning in Southwest Idaho in the Intermountain West region, USA was studied. Applications of ACC reduced fruit set in ‘Schlect Spur Delicious’ in 7 and 30 days after application. Acc applications reduced fruit set in ‘Gala’ and ‘Fuji’ apples 30 days after application. Fruit weight after 30 days of ACC application (hand thinning time) in trees receiving ACC was higher than those in Untreated Control and the difference was significant only in ‘Schlect Spur Delicious’ apple. Application of ACC at 300 mg·L−1 or 365 mg·L−1 in this study did not have any advese effects on foliage or fruit skin in any of the tested cultivars in this project.

Impacts of 1-Aminocyclopropane-1-Carboxylic Acid as a Late Post-Bloom Thinner on Fruit Set, Yield, and Fruit Quality in “Gala” and “Fuji” Apples

A few post-bloom thinners are available for apple (Malus domestica Borkh.) and the prospects for additional thinners appear to be limited. Application of blossom thinners may present a risk of overthining in the areas where weather is less predictable. Thus, we studied the impacts of various rates of 1-aminocyclopropane-1-carboxylic acid (ACC) in three strains of “Fuji” apple and different rates of ACC and one rate of Ethrel in “Buckeye Gala” apple, when fruitlet diameter was about 20 mm, on fruit set, yield and fruit quality attributes at harvest, and return bloom in southwest Idaho in the Intermountain West region, USA. In 2013, application of Ethrel at 300 mg·L-1 did not affect fruit set, fruit weight, diameter (D), length(L), or L/D ratio 34 days after application, or yield, fruit weight, color, russet, and starch degradation pattern (SDP) at harvest, while application of ACC at 150 mg·L-1 or higher reduced fruit set by 19% to 34% in “Buckeye Gala” apple. In this cultivar, application of ACC at 350 mg·L-1 significantly increased fruit weight, diameter and length 34 days after application, and increased fruit weight, color, and SDP at harvest time. Application of ACC at all rates reduced total yield per tree in “Buckeye Gala”. Application of ACC at 300 mg·L-1 significantly reduced fruit set but applications of 150 mg·L-1 or 300 mg·L-1 ACC did not affect yield or quality attributes of “Sun Fuji” apple in Sunny Slope area in 2013. Application of ACC reduced fruit set and slightly increased fruit size in “Top Export Fuji” in 2013. Application of ACC at 600 mg·L-1 significantly reduced fruit set in “Aztec Fuji” apple in 2014. Application of ACC in a season never reduced bloom density (return bloom) of the next season. Overall, we conclude that ACC is an excellent tool as a late-season post-bloom fruit thinner and can be effective when applied fruitlet diameter is about 20 mm.

Fusarium verticillioides Induces Maize-Derived Ethylene to Promote Virulence by Engaging Fungal G-Protein Signaling.

Seed maceration and contamination with mycotoxin fumonisin inflicted by Fusarium verticillioides is a major disease concern for maize producers worldwide. Meta-analyses of quantitative trait loci for Fusarium ear rot resistance uncovered several ethylene (ET) biosynthesis and signaling genes within them, implicating ET in maize interactions with F. verticillioides. We tested this hypothesis using maize knockout mutants of the 1-aminocyclopropane-1-carboxylate (ACC) synthases ZmACS2 and ZmACS6. Infected wild-type seed emitted five-fold higher ET levels compared with controls, whereas ET was abolished in the acs2 and acs6 single and double mutants. The mutants supported reduced fungal biomass, conidia, and fumonisin content. Normal susceptibility was restored in the acs6 mutant with exogenous treatment of ET precursor ACC. Subsequently, we showed that fungal G-protein signaling is required for virulence via induction of maize-produced ET. F. verticillioides Gβ subunit and two regulators of G-protein signaling mutants displayed reduced seed colonization and decreased ET levels. These defects were rescued by exogenous application of ACC. We concluded that pathogen-induced ET facilitates F. verticillioides colonization of seed, and, in turn, host ET production is manipulated via G-protein signaling of F. verticillioides to facilitate pathogenesis.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Photoperiod- and temperature-mediated control of the ethylene response and winter dormancy induction in Prunus mume

Plant dormancy is essential for perennial plant survival. Different genotypes of Prunus mume, including Eumume group and Apricot Mei group, undergo leaf senescence and dormancy at different times. In order to verify the cold resistance of P. mume, freeze resistance evaluation was carried out. Our results showed that Apricot Mei group had a stronger freezing tolerance than Eumume group and that leaf senescence and dormancy of Apricot Mei group occurred at an earlier period before winter. Based on phenotypic data in response to seasonal climate change, the significant candidate regions were selected using GWAS. Furthermore, through KEGG pathway and qRT-PCR analyses, we found that the ethylene-related genes, including PmEIL (Pm002057) and PmERF (Pm004265), were significantly upregulated in ‘Songchun’ Mei (Apricot Mei group) and downregulated in ‘Zaohua Lve’ Mei (Eumume group). Ethylene-related genes expression models showed that ethylene may be indirectly involved in the induction of dormancy. The PmEIL and PmERF genes were the core genes of the ethylene signal transduction pathway and were regulated by the exogenous ACC or PZA compounds. For non-dormant or weekly dormant perennial plants, application of ACC was able to induce plant dormancy and thus enhance cold/freeze tolerance. Overall, the expression of the major ethylene genes played a significant role in dormancy induction and freezing tolerance in P. mume; accordingly, application of ACC and PZA compounds were an effective approach for enhancing cold/freeze of tolerance of woody plant.

Host-produced ethylene is required for marked cell expansion and endoreduplication in dodder search hyphae.

The genus Cuscuta comprises stem holoparasitic plant species with wide geographic distribution. Cuscuta spp. obtain water, nutrients, proteins, and mRNA from their host plants via a parasitic organ called the haustorium. As the haustorium penetrates into the host tissue, search hyphae elongate within the host tissue and finally connect with the host's vascular system. Invasion by Cuscuta spp. evokes various reactions within the host plant's tissues. Here, we show that, when Arabidopsis (Arabidopsis thaliana) is invaded by Cuscuta campestris, ethylene biosynthesis by the host plant promotes elongation of the parasite's search hyphae. The expression of genes encoding 1-aminocylclopropane-1-carboxylic acid (ACC) synthases, ACC SYNTHASE2 (AtACS2) and ACC SYNTHASE6 (AtACS6), was activated in the stem of Arabidopsis plants upon invasion by C. campestris. When the ethylene-deficient Arabidopsis acs octuple mutant was invaded by C. campestris, cell elongation and endoreduplication of the search hyphae were significantly reduced, and the inhibition of search hyphae growth was complemented by exogenous application of ACC. In contrast, in the C. campestris-infected Arabidopsis ethylene-insensitive mutant etr1-3, no growth inhibition of search hyphae was observed, indicating that ETHYLENE RESPONSE1-mediated ethylene signaling in the host plant is not essential for parasitism by C. campestris. Overall, our results suggest that C. campestris recognizes host-produced ethylene as a stimulatory signal for successful invasion.

A Salt-Signaling Network Involving Ethylene, Extracellular ATP, Hydrogen Peroxide, and Calcium Mediates K+/Na+ Homeostasis in Arabidopsis.

This work aimed at investigating the interactive effects of salt-signaling molecules, i.e., ethylene, extracellular ATP (eATP), H2O2, and cytosolic Ca2+ ([Ca2+]cyt), on the regulation of K+/Na+ homeostasis in Arabidopsis thaliana. The presence of eATP shortened Col-0 hypocotyl length under no-salt conditions. Moreover, eATP decreased relative electrolyte leakage and lengthened root length significantly in salt-treated Col-0 plants but had no obvious effects on the ethylene-insensitive mutants etr1-1 and ein3-1eil1-1. Steady-state ionic flux kinetics showed that exogenous 1-aminocyclopropane-1-carboxylic acid (ACC, an ethylene precursor) and eATP-Na2 (an eATP donor) significantly increased Na+ extrusion and suppressed K+ loss during short-term NaCl treatment. Moreover, ACC remarkably raised the fluorescence intensity of salt-elicited H2O2 and cytosolic Ca2+. Our qPCR data revealed that during 12 h of NaCl stress, application of ACC increased the expression of AtSOS1 and AtAHA1, which encode the plasma membrane (PM) Na+/H+ antiporters (SOS1) and H+-ATPase (H+ pumps), respectively. In addition, eATP markedly increased the transcription of AtEIN3, AtEIL1, and AtETR1, and ACC treatment of Col-0 roots under NaCl stress conditions caused upregulation of AtRbohF and AtSOS2/3, which directly contribute to the H2O2 and Ca2+ signaling pathways, respectively. Briefly, ethylene was triggered by eATP, a novel upstream signaling component, which then activated and strengthened the H2O2 and Ca2+ signaling pathways to maintain K+/Na+ homeostasis under salinity.

Phytohormone profiles are strongly altered during induction and symptom development of the physiological ripening disorder berry shrivel in grapevine

The process of grape berry ripening follows three phases with distinct metabolic processes and complex regulations via phytohormones. The physiological ripening disorder berry shrivel (BS) is characterized by reduced sugar accumulation, low anthocyanin contents, and high acidity in affected berries. The processes leading to BS induction are unknown, but recent transcriptional data on reduced expression of switch genes hint towards a disturbed ripening onset. Herein we investigated the phytohormone composition throughout grape berry ripening in healthy and BS berries in Vitis vinifera L. cultivar Blauer Zweigelt. Thereby we hypothesize that phytohormones are key players for BS induction and suppress the expression of switch genes at veraison. The presented metabolomics and RNAseq data describe two distinct phytohormone profiles in BS berries, differing between pre- and post-veraison with a clear ethylene precursor (aminocyclopropane-1-carboxylic acid, ACC) peak before veraison. Exogenous application of ACC led to BS symptoms, while ethephone application led to berry abscission. During post-veraison, we observed high ABA-glucose ester (ABA-GE) and low indole-3-acetate aspartate (IAA-Asp) and isopentenyladenine (iP) contents in BS berries and the transcriptional induction of several phytohormone pathways. The presented descriptive data provide valuable knowledge to further decipher the role of phytohormones in BS induction and BS symptom development.

Sexual Reproduction via a 1-Aminocyclopropane-1-Carboxylic Acid-Dependent Pathway Through Redox Modulation in the Marine Red Alga Pyropia yezoensis (Rhodophyta).

The transition from the vegetative to sexually reproductive phase is the most dynamic change to occur during a plant's life cycle. In the present study, we showed that the ethylene precursor 1-aminocylopropane-1-carboxylic acid (ACC) induces sexual reproduction in the marine red alga Pyropia yezoensis independently from ethylene. Exogenous application of ACC, which contains a three membered carbocyclic ring, promoted the formation of spermatia and carporspores in gametophytes, whereas ethephon, an ethylene-releasing compound, did not stimulate sexual reproduction. In addition, an ACC analog, 1-aminocyclobutane-1-carboxylic acid (ACBC), which contains a four membered carbocyclic ring, promoted sexual reproduction and enhanced tolerance to oxidative stress in the same manner as ACC, but 1-aminocyclopentane-1-carboxylic acid (cycloleucine; which contains a cyclopentane ring) did not. The application of ACC increased the generation of reactive oxygen species (ROS) and induced the expression of PyRboh gene encoding NADPH oxidase. ACC also stimulated the synthesis of ascorbate (AsA) by inducing transcripts of PyGalLDH, which encodes galactono-1,4-lactone dehydrogenase, the catalyst for the final enzymatic step of the AsA biosynthetic pathway. Conversely, ACC caused a decrease in the synthesis of glutathione (GSH) by repressing transcripts of PyGCL, which encodes glutamate cysteine ligase, the catalyst for the rate-limiting step in the formation of GSH. These results suggest a possible role played by ACC as a signaling molecule independent from ethylene in the regulation of sexual reproduction through alterations to the redox state in P. yezoensis.

1-Aminocyclopropane 1-Carboxylic Acid and Its Emerging Role as an Ethylene-Independent Growth Regulator.

1-Aminocyclopropane 1-carboxylic acid (ACC) is the direct precursor of the plant hormone ethylene. ACC is synthesized from S-adenosyl-L-methionine (SAM) by ACC synthases (ACSs) and subsequently oxidized to ethylene by ACC oxidases (ACOs). Exogenous ACC application has been used as a proxy for ethylene in numerous studies as it is readily converted by nearly all plant tissues to ethylene. However, in recent years, a growing body of evidence suggests that ACC plays a signaling role independent of the biosynthesis. In this review, we briefly summarize our current knowledge of ACC as an ethylene precursor, and present new findings with regards to the post-translational modifications of ACS proteins and to ACC transport. We also summarize the role of ACC in regulating plant development, and its involvement in cell wall signaling, guard mother cell division, and pathogen virulence.

NbALD1 mediates resistance to turnip mosaic virus by regulating the accumulation of salicylic acid and the ethylene pathway in Nicotiana benthamiana.

SummaryAGD2‐LIKE DEFENCE RESPONSE PROTEIN 1 (ALD1) triggers plant defence against bacterial and fungal pathogens by regulating the salicylic acid (SA) pathway and an unknown SA‐independent pathway. We now show that Nicotiana benthamiana ALD1 is involved in defence against a virus and that the ethylene pathway also participates in ALD1‐mediated resistance. NbALD1 was up‐regulated in plants infected with turnip mosaic virus (TuMV). Silencing of NbALD1 facilitated TuMV infection, while overexpression of NbALD1 or exogenous application of pipecolic acid (Pip), the downstream product of ALD1, enhanced resistance to TuMV. The SA content was lower in NbALD1‐silenced plants and higher where NbALD1 was overexpressed or following Pip treatments. SA mediated resistance to TuMV and was required for NbALD1‐mediated resistance. However, on NahG plants (in which SA cannot accumulate), Pip treatment still alleviated susceptibility to TuMV, further demonstrating the presence of an SA‐independent resistance pathway. The ethylene precursor, 1‐aminocyclopropanecarboxylic acid (ACC), accumulated in NbALD1‐silenced plants but was reduced in plants overexpressing NbALD1 or treated with Pip. Silencing of ACS1, a key gene in the ethylene pathway, alleviated the susceptibility of NbALD1‐silenced plants to TuMV, while exogenous application of ACC compromised the resistance of Pip‐treated or NbALD1 transgenic plants. The results indicate that NbALD1 mediates resistance to TuMV by positively regulating the resistant SA pathway and negatively regulating the susceptible ethylene pathway.

Effects of 1-aminocyclopropane-1-carboxylate and paclobutrazol on the endogenous hormones of two contrasting rice varieties under submergence stress

Phytohormone play important roles in regulating developmental processes and signaling networks involved in plant responses to submergence stress. We studied the growth, leaf endogenous hormonal levels and related genes of two contrasting rice genotypes (IR64 and IR64-Sub1) pretreated with 1-aminocyclopropane-1-carboxylate (ACC) and paclobutrazol (PB) under submergence conditions. Submergence promoted underwater shoot elongation, chlorophyll degradation and expression of OsCIPK15, altered the leaf endogenous hormone levels, accelerated the yellowing and senescence of leaves, and decreased shoot dry weight and the plant survival rate. IR64 was more sensitive to submergence stress, showing larger increases of leaf GAs, ABA, IAA contents and the expression of OsCPS1, OsGA20ox1 and OsIAA11, which in IR64-Sub1 were significantly decreased with prolonged stress. Furthermore, IR64 showed decreased ZR content, cZOGT1 expression, GA/ABA and ZR/IAA, while IR64-Sub1 showed opposite trends. Shoot elongation, leaf yellowing and senescence, GAs and IAA contents and the expression of OsCPS1, OsGA20ox1 and OsIAA11 in submerged rice leaves were enhanced by ACC application, whereas PB treatment showed opposite effects, and the effects on underwater elongation of PB and Sub1 were clearly superimposable. Compared with GA/ABA, ZR/IAA was not only suitable for non-Sub1 genotypes, but also more accurate in reflecting the submergence characteristics in IR64-Sub1. These findings improve our understanding of the intricate web of connections between plant hormones that regulate physiological responses to stress.

APD1, the unique member of Arabidopsis AP2 family influences systemic acquired resistance and ethylene-jasmonic acid signaling

Arabidopsis AP2 FAMILY PROTEIN INVOLVED IN DISEASE DEFENSE (APD1) is a member of AP2/EREBP super-family that positively regulates SA biosynthesis and defense against virulent bacterial pathogens. Here we report additional roles of APD1 in plant defense and development. We show that APD1 function is required for light-mediated defense against bacterial pathogens and systemic acquired resistance (SAR). We demonstrate that APD1 function is not required for generating SAR mobile signal at the site of primary inoculation but is required at the distal end for SAR manifestation. In addition, the APD1 function is required for PTI-induced callose deposition, defense against necrotrophic pathogen Botrytis cinerea and Alternaria alternata, which are ethylene (ET) or ethylene-Jasmonate (JA) dependent responses. Development of seedling under dark and ET is partly dependent on APD1. The mutant apd1 plants are non-responsive towards exogenous ACC application regarding apical hook formation and hypocotyl shortening, however, possess WT-like ET-mediated root growth inhibition. JA-mediated root growth inhibition is also impaired in apd1 seedlings. Altogether our results suggest that APD1 impacts multiple aspects of plant growth and development.

Ethylene signaling induces gelatinous layers with typical features of tension wood in hybrid aspen.

The phytohormone ethylene impacts secondary stem growth in plants by stimulating cambial activity, xylem development and fiber over vessel formation. We report the effect of ethylene on secondary cell wall formation and the molecular connection between ethylene signaling and wood formation. We applied exogenous ethylene or its precursor 1-aminocyclopropane-1-carboxylic acid (ACC) to wild-type and ethylene-insensitive hybrid aspen trees (Populus tremula×tremuloides) and studied secondary cell wall anatomy, chemistry and ultrastructure. We furthermore analyzed the transcriptome (RNA Seq) after ACC application to wild-type and ethylene-insensitive trees. We demonstrate that ACC and ethylene induce gelatinous layers (G-layers) and alter the fiber cell wall cellulose microfibril angle. G-layers are tertiary wall layers rich in cellulose, typically found in tension wood of aspen trees. A vast majority of transcripts affected by ACC are downstream of ethylene perception and include a large number of transcription factors (TFs). Motif-analyses reveal potential connections between ethylene TFs (Ethylene Response Factors (ERFs), ETHYLENE INSENSITIVE 3/ETHYLENE INSENSITIVE3-LIKE1 (EIN3/EIL1)) and wood formation. G-layer formation upon ethylene application suggests that the increase in ethylene biosynthesis observed during tension wood formation is important for its formation. Ethylene-regulated TFs of the ERF and EIN3/EIL1 type could transmit the ethylene signal.

Endogenous Ethylene Concentration Is Not a Major Determinant of Fruit Abscission in Heat-Stressed Cotton (Gossypium hirsutum L.).

We investigated the role of ethylene in the response of cotton to high temperature using cotton genotypes with genetically interrupted ethylene metabolism. In the first experiment, Sicot 71BRF and 5B (a lintless variant with compromised ethylene metabolism) were exposed to 45°C, either by instantaneous heat shock or by ramping temperatures by 3°C daily for 1 week. One day prior to the start of heat treatment, half the plants were sprayed with 0.8 mM of the ethylene synthesis inhibitor, aminoethoxyvinylglycine (AVG). In a subsequent experiment, Sicot 71BRF and a putatively heat-tolerant line, CIM 448, were exposed to 36 or 45°C for 1 week, and half the plants were sprayed with 20 μM of the ethylene precursor, 1-aminocyclopropane-1-carboxylic acid, (ACC). High temperature exposure of plants in both experiments was performed at the peak reproductive phase (65–68 days after sowing). Elevated temperature (heat shock or ramping to 45°C) significantly reduced production and retention of fruits in all cotton lines used in this study. At the termination of heat treatment, cotton plants exposed to 45°C had at least 50% fewer fruits than plants under optimum temperature in all three genotypes, while plants at 36°C remained unaffected. Heat-stressed plants continued producing new squares (fruiting buds) after termination of heat stress but these squares did not turn into cotton bolls due to pollen infertility. In vitro inhibition of pollen germination by high temperatures supported this observation. Leaf photosynthesis (Pn) of heat-stressed plants (45°C) measured at the end of heat treatments remained significantly inhibited, despite an increased leaf stomatal conductance (gs), suggesting that high temperature impairs Pn independently of stomatal behavior. Metabolic injury was supported by high relative cellular injury and low photosystem II yield of the heat-stressed plants, indicating that high temperature impaired photosynthetic electron transport. Both heat shock and ramping of heat significantly reduced ethylene release from cotton leaf tissues measured at the end of heat treatment but modulating ethylene production via AVG or ACC application had no significant effect on fruit production or retention in heat-stressed cotton plants. Instead, high temperature accelerated fruit abortion by impairing pollen development and/or restricting leaf photosynthesis.

특수학교 AAC 연구동아리 ‘보통날’의 지도 사례보고

Background and Objectives: Augmentative and Alternative Communication (AAC) study circle’s concept of an ‘ordinary day’ involves two daily experiences. First, special needs students attempt to have a everyday conversation similar to conversation that ordinary people would have. Second, ‘ordinary day’, in Korean, means “to give it wings” and special needs students, using AAC, apply this principle. The purpose of this study is to prove the importance of AAC for special needs students and to provide higher quality interventions through study circle experiences. The overall goal of ACC study circles is to allow special needs students to experience life as similarly to ordinary people as possible. Method: The interventions of script, school schedule, peer tutoring, etc., appropriate for the degree or attribute of disability, were conducted for three special needs students who have difficulty communicating. The interventions were implemented using an ACC application installed on a smart device. Results: After the implementation of interventions, special needs students could express most objective vocabulary through AAC. In addition, it was found that the increase of communication behavior decreased problem behaviors. Conclusion: Special needs students can appear to have behavior problems or limited participation in learning in school. Therefore, we should continue to give attention to the students who have difficulty in expressing their feelings and thoughts due to physical or cognitive problems. AAC study circle’s ‘ordinary day’ will have two AAC interventions for students and looks forward to helping students change in a positive manner, as seen in this case.

The role of ethylene in abscission of sweet orange promoted by exogenous application of the abscission agent 5-chloro-3-methyl-4-nitro-1H-pyrazole (CMNP)

ABSTRACTMature ‘Valencia’ fruit were treated with 5-chloro-3-methyl-4-nitro-1H-pyrazole (CMNP), and the ethylene inhibitors aminoethoxy vinyl glycine (AVG) and silver thiosulfate (STS), to assess involvement of ethylene in abscission via CMNP. Fruit detachment force (FDF) and ethylene evolution were measured over time. Accumulation of the ethylene precursor 1-aminocyclopropane-1-carboxylate (ACC) in peel upon CMNP application was assessed and impact of application of ACC on FDF was estimated when applied 1 cm away from the abscission zone (AZ), to determine its potential as a signaling molecule in promoting fruit loosening. CMNP when applied alone reduced FDF by 50%. AVG and STS inhibited fruit loosening considerably at 500 µM and 10 mM, respectively, when applied with 2 mM CMNP. ACC accumulation in peel was highest 2 days after CMNP application, which preceded the maximum decline in FDF which occurred a day later, indicating that ACC serves as a potential signaling molecule that triggers abscission in the AZ. The results of the study support the hypothesis that abscission via CMNP application is at least partly ethylene dependent. However, the decline in FDF by ACC was less than 50% of control which suggested involvement of another pathway in abscission via CMNP in sweet orange.