2-chloroethylphosphonic Acid Research Articles

Ethylene promotes mycelial growth and ganoderic acid biosynthesis in Ganoderma lucidum.

To investigate the effects of ethylene, in the form of ethephon (2-chloroethylphosphonic acid), on mycelial growth and ganoderic acid (GA) accumulation in the higher basidiomycete Ganoderma lucidum. Treatment with both 10 and 15mM ethephon enhanced the growth of G. lucidum on solid CYM plates and in CYM liquid medium. After optimization using response surface methodology, GA reached 33mg/g dry cell weight (DW), an increase of 90%, compared with the control. Lanosterol and squalene contents were 31 and 2.4μg/g DW, being increased by 1.2- and 0.6-fold, respectively, in response to ethephon. Additionally, the transcriptional levels of hydroxymethylglutaryl-CoA reductase, squalene synthase and oxidosqualene cyclase were up-regulated by 2.6-, 4.3- and 3.8-fold, respectively, compared with the control group. This approach provides an efficient strategy for improving GA accumulation in G. lucidum, with potential future applications.

Elicitation of galanthamine and lycorine biosynthesis by Leucojum aestivum L. and L. aestivum ‘Gravety Giant’ plants cultured in bioreactor RITA®

In order to establish an attractive method for the production of valuable medicinal alkaloids (galanthamine and lycorine), the plants of Leucojum aestivum and L. aestivum ‘Gravety Giant’ grown in bioreactor RITA® were subjected to various concentrations of methyl jasmonate (MeJA), salicylic acid (SA), 1-aminocyclopropane-1-carboxylic acid (ACC) and 2-chloroethylphosphonic acid (ethephon) at different times of culture. The application of MeJA showed a negative effect on L. aestivum and L. aestivum ‘Gravety Giant’ plant growth. We observed that the incubation of plants during 168 h with 100 µM of MeJA resulted above two times lower F.W. (fresh weight) increments compared with control. While SA showed an inhibitory effect only on the growth of L. aestivum cultures. ACC and ethephon had a positive effect on both types of culture. Treatment with 50 µM of MeJA during 168 h stimulated galanthamine and lycorine biosynthesis in L. aestivum and L. aestivum ‘Gravety Giant’ cultures. In addition, the accumulation of galanthamine was increased when 10 µM of ACC were added to both types of culture. 10 µM of ACC stimulated also lycorine biosynthesis by L. aestivum ‘Gravety Giant’. The addition of 10 µM of ethephon had a positive effect only on lycorine production in plants of L. aestivum. SA promoted galanthamine and lycorine biosynthesis in tested plants. Indeed the highest galanthamine (0.8 mg/g dry weight: D.W.) and lycorine (1.53 mg/g D.W.) concentrations were observed in L. aestivum ‘Gravety Giant’ plants treated with 5 µM of SA during 10 h.

Novel Ethephon Application Methods for Narcissus

Ethephon [(2-chloroethyl) phosphonic acid] is a plant growth regulator (PGR) that releases ethylene following application. Although ethephon is commonly used as a foliar spray during the commercial production of ornamental crops, including spring bulb crops such as daffodil (Narcissus pseudonarcissus L.), there has been increased interest in using ethephon as a root-zone-applied PGR. In this work, we evaluated a number of factors important for the development of ethephon as a soil drench for daffodil. Results indicate that a given dose (milligrams ethephon per pot) could be applied in volumes ranging from 15 to 120 mL (per 15-cm pot) with equal efficacy. Similarly, the same dose of ethephon could be applied as a foliar/substrate surface spray with volume of 105 to 525 mL·m−2 with equal efficacy. Although the efficacy of ethephon drenches interacted with forcing temperature, drenches were nonetheless effective across the range of temperatures commonly used for daffodil production. Plant size at the time of ethephon application had no effect on final plant size (at flower senescence). The rate of ethylene release from a peat-based substrate was highly temperature dependent, and ethephon was readily leached from this same substrate.

Roles of ethylene and cytokinins in development of defense responses in Triticum aestivum plants infected with Septoria nodorum

Effects of ethephon (2-chloroethylphosphonic acid, ET), which is a producer of ethylene, and 1-methylcyclopropene (1-MCP), which inhibits ethylene binding with the corresponding receptors, on defense responses caused by the causal agent of leaf blotch (Septoria nodorum Berk.) in leaves of soft spring wheat (Triticum aestivum L.) of cultivars contrast in the resistance to the pathogen were studied. After treatment with 1-MCP, an induction of wheat resistance to the disease, more prominent in the susceptible cv. Kazakhstanskaya 10 than in the resistant cv. Omskaya 35, was found. The rise in the resistance was accompanied by rise in zeatin content in leaves, enhanced generation of hydrogen peroxide (most likely, due to the decreased catalase activity and increased peroxidase activity), and accumulation of transcripts of marker genes of the salicylate signaling pathway (PR-1 and PR-2). On the contrary, in ET-treated plants, all the studied defense responses were inhibited, and the pathogen developed more intensively. The effect of ethylene on zeatin distribution in infected wheat leaves of the susceptible cv. Kazakhstanskaya 10 was also found. In the 1-MCP-treated wheat leaves, cytokinins were localized in mesophyll cells and cell walls. In the ET-treated leaves, cell walls were free of zeatin, and the hormone concentrated in developing hyphae of the pathogen. The results allow for the hypothesis that wheat plant resistance is controlled by antagonistic interaction of signaling pathways of salicylic acid and ethylene with participation of cytokinins.

Growth regulators and carving on breakage of apical dominance in tannia [Xanthosoma sagittifolium (L.) Schott] rhizomes

Specific clones of tannia are commonly used as cooking leaves in some Brazilian states. The crop is propagated exclusively as exually by planting the rhizomes usually after a few years of production. Because of that, there is the need to establish strategies to propagate healthy plantlets with higher sprouting rate for leaf production. This work had the goals to evaluate the influence of growth regulators and carving of the rhizomes sprouting and growth of tannia. Cured rhizomes from the clone ‘Caipira’ were stored for three months at 5oC and 89% relative humidity. Afterward, the top of half of the rhizomes were carved in a V shape at the top (carving), to stimulate lateral sprouting. The rhizomes were submerged for 30 minutes in solutions containing 6-benzylaminopurine (BAP) and/or 2chloroethylphosphonic acid (ethephon), and the respective control. The production of new leaves and expansion of leaf area were stimulated by treating the rhizomes with 500 mg L -1 BAP and 250 mg L -1 BAP + 250 mg L -1 ethephon. Regardless the use of growth regulators, the carving induced higher number of new sprouted leaves after 35 days of planting. Similarly, rhizomes treated with 500 mg L -1 BAP or 250 mg L -1 BAP + 250 mg L -1 ethephon had higher number of sprouts after 49 days of planting. Sprouting was anticipated when the carved rhizomes were treated with 250 mg L -1 BAP + 250 mg L -1 ethephon.

Interaction of plant growth regulators and reactive oxygen species to regulate petal senescence in wallflowers (Erysimum linifolium).

BackgroundIn many species floral senescence is coordinated by ethylene. Endogenous levels rise, and exogenous application accelerates senescence. Furthermore, floral senescence is often associated with increased reactive oxygen species, and is delayed by exogenously applied cytokinin. However, how these processes are linked remains largely unresolved. Erysimum linifolium (wallflower) provides an excellent model for understanding these interactions due to its easily staged flowers and close taxonomic relationship to Arabidopsis. This has facilitated microarray analysis of gene expression during petal senescence and provided gene markers for following the effects of treatments on different regulatory pathways.ResultsIn detached Erysimum linifolium (wallflower) flowers ethylene production peaks in open flowers. Furthermore senescence is delayed by treatments with the ethylene signalling inhibitor silver thiosulphate, and accelerated with ethylene released by 2-chloroethylphosphonic acid. Both treatments with exogenous cytokinin, or 6-methyl purine (which is an inhibitor of cytokinin oxidase), delay petal senescence. However, treatment with cytokinin also increases ethylene biosynthesis. Despite the similar effects on senescence, transcript abundance of gene markers is affected differentially by the treatments. A significant rise in transcript abundance of WLS73 (a putative aminocyclopropanecarboxylate oxidase) was abolished by cytokinin or 6-methyl purine treatments. In contrast, WFSAG12 transcript (a senescence marker) continued to accumulate significantly, albeit at a reduced rate. Silver thiosulphate suppressed the increase in transcript abundance both of WFSAG12 and WLS73. Activity of reactive oxygen species scavenging enzymes changed during senescence. Treatments that increased cytokinin levels, or inhibited ethylene action, reduced accumulation of hydrogen peroxide. Furthermore, although auxin levels rose with senescence, treatments that delayed early senescence did not affect transcript abundance of WPS46, an auxin-induced gene.ConclusionsA model for the interaction between cytokinins, ethylene, reactive oxygen species and auxin in the regulation of floral senescence in wallflowers is proposed. The combined increase in ethylene and reduction in cytokinin triggers the initiation of senescence and these two plant growth regulators directly or indirectly result in increased reactive oxygen species levels. A fall in conjugated auxin and/or the total auxin pool eventually triggers abscission.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-016-0766-8) contains supplementary material, which is available to authorized users.

エテホンと6-ベンジルアミノプリンを組み合わせた前処理がチューリップ切り花の品質保持期間に及ぼす効果

エテホンと6-ベンジルアミノプリンを組み合わせた前処理がチューリップ切り花の品質保持期間に及ぼす効果

The Phytohormone Ethylene Enhances Cellulose Production, Regulates CRP/FNRKx Transcription and Causes Differential Gene Expression within the Bacterial Cellulose Synthesis Operon of Komagataeibacter (Gluconacetobacter) xylinus ATCC 53582.

Komagataeibacter (formerly Gluconacetobacter) xylinus ATCC 53582 is a plant-associated model organism for bacterial cellulose (BC) biosynthesis. This bacterium inhabits the carposphere where it interacts with fruit through the bi-directional transfer of phytohormones. The majority of research regarding K. xylinus has been focused on identifying and characterizing structural and regulatory factors that control BC biosynthesis, but its ecophysiology has been generally overlooked. Ethylene is a phytohormone that regulates plant development in a variety of ways, but is most commonly known for its positive role on fruit ripening. In this study, we utilized ethephon (2-chloroethylphosphonic acid) to produce in situ ethylene to investigate the effects of this phytohormone on BC production and the expression of genes known to be involved in K. xylinus BC biosynthesis (bcsA, bcsB, bcsC, bcsD, cmcAx, ccpAx and bglAx). Using pellicle assays and reverse transcription quantitative polymerase chain reaction (RT-qPCR), we demonstrate that ethephon-derived ethylene enhances BC directly in K. xylinus by up-regulating the expression of bcsA and bcsB, and indirectly though the up-regulation of cmcAx, ccpAx, and bglAx. We confirm that IAA directly decreases BC biosynthesis by showing that IAA down-regulates bcsA expression. Similarly, we confirm that ABA indirectly influences BC biosynthesis by showing it does not affect the expression of bcs operon genes. In addition, we are the first to report the ethylene and indole-3-acetic acid (IAA) induced differential expression of genes within the bacterial cellulose synthesis (bcs) operon. Using bioinformatics we have identified a novel phytohormone-regulated CRP/FNRKx transcription factor and provide evidence that it influences BC biosynthesis in K. xylinus. Lastly, utilizing current and previous data, we propose a model for the phytohormone-mediated fruit-bacteria interactions that K. xylinus experiences in nature.

English

The effect of banana treatment with traditional kerosene smoking and ethrel released ethylene were investigated to determine their efficacy on ripening, shelf life and physicochemical quality attributes. Fruits at full maturity stage that are light green and three quarter full were used. The study was consisted of three factors namely ripening techniques (conventional kerosene smoking and Ethrel), exposure times (that is, 18, 24 and 30 h), and cultivars (Williams I, Poyo and Giant Cavendish). Fruits were conventionally treated with kerosene smoke released from kerosene burners and ethylene released from 10 ml of ethrel solution (2-chloro ethyl phosphonic acid). They were equally treated under airtight conditions over three sets of exposure times inside locally standard 3 m × 2 m × 3 m sized six separate commercial banana ripening chambers. Fruits were then sequentially withdrawn from the chambers on the basis of their respective exposure times and studied under ambient conditions (23±1°C and 73±1% RH). All parameters tested were invariably and progressively affected by treatment combinations over the experimental period. Significant differences (p ≤ 0.05) in mean values were also recorded in all parameters at different stages of the ripening period. A three way significant (p ≤ 0.05) interaction effect of the three factors was revealed on the 7th day of the ripening period on the major quality parameters, starch, TSS, and TSS/TA. Sensory quality evaluation results conducted on the 7th day of the ripening period also showed a similarly highly significant interaction effect among the treatment factors on all quality attributes tested. Ethrel treated fruits demonstrated higher sensory quality mean score values in color (3.85), flavor (3.89), taste (3.80), aroma (3.66) and total acceptability (3.67), other than mouth- feel (3.37) and degree of ripening (3.49). Fruits treated with all treatment combinations of the kerosene smoking system equally completed their maximum ripening stage on the 7th day of the ripening period. However, at this stage, fruits were found developing some off ripening effect black scars on the peel in addition to the relatively low quality attributes recorded upon them through the sensory evaluation panel. Fruits treated with ethrel completed their ripening stage on the 7th day only at the exposure time of 30 h. Those exposed to 18 and 24 h exposure times took more time and extended their ripening stage to up to the 11th day. Thus, in terms of ripening efficiency, the kerosene smoking system can be used at the lowest exposure time of 18 h under the conditions tested. The ethrel-based ripening system can similarly be used for equal ripening efficiency and better sensory quality attributes but only at the highest exposure time of 30 h. Key words: Banana, ripening, shelf life, physicochemical quality, kerosene smoking, ethrel.

Quality Characteristics, Carbon Dioxide, and Ethylene Production of Asparagus (Asparagus officinalis L.) Treated with 1-Methylcyclopropene and 2-Chloroethylphosphonic Acid during Storage

Quality Characteristics, Carbon Dioxide, and Ethylene Production of Asparagus (Asparagus officinalis L.) Treated with 1-Methylcyclopropene and 2-Chloroethylphosphonic Acid during Storage

Substrate pH Impacts Efficacy of Ethephon Drenches on Growth of Herbaceous Perennials

Ethephon [(2-chloroethyl) phosphonic acid] is widely used as a growth regulator in floricultural crop production, with foliar sprays as the typical application method. Ethephon efficacy is determined by rate of uptake and subsequent ethylene evolution, which can be influenced by a number of factors, including solution pH. This study examines whether an ethephon substrate drench (100 mg⋅L−1 at a volume of 296 mL per 2.8-L container) would allow for plant uptake in two herbaceous perennials, Verbena bonariensis (L.) ‘Lollipop’ and Veronica spicata (L.) ‘Goodness Grows’, as measured by subsequent effects on shoot growth and days to flower. We also investigated substrate pH effects on ethephon drench efficacy by analyzing the shoot responses to ethephon applied at a range of starting substrate pH (4.5 to 7.0) compared with untreated plants grown under the same substrate pH conditions (controls). One or more measurements of shoot growth (height, width, shoot dry weight) were reduced in both taxa treated with ethephon as compared with controls. Veronica plant growth was not influenced by substrate pH in either the control or ethephon-drenched plants. For Verbena plants receiving the ethephon drench, as substrate pH increased, height and width increased. For example, when ethephon was applied at substrate pH 4.5, finished plant height averaged 32.0 cm, compared with 43.5 cm for those plants that received the drench at a substrate pH of 7.0. Increasing substrate pH conditions also influenced the days to flower in Verbena plants. Ethephon-treated plants at a substrate pH of 4.5 required an average of 6.5 days longer to flower than those at a substrate pH of 7.0. In summary, ethephon drench applications can result in significant growth regulation effects, as seen in both Veronica and Verbena. Furthermore, increasing substrate pH can reduce the efficacy of ethephon drench applications.

English

Effective chemical hybridizing agents (CHAs) or male gametocides enhance cross pollination in plant breeding and genetic analysis of traits. The present study examined the efficacy and optimum concentration of four CHAs, namely: 2-chloroethyl phosphonic acid (Ethrel), ethyl 4'-fluorooxanilate (E4FO), 2, 4-dichlorphenoxy acetic acid (2, 4-D) and Promalin ® (1.8% GA 47 – gibberellins A 4 +A 7 and 1.8% 6-BA–benzyladenine) on pollen sterility and seeding of a tef line (DZ-01-3186). Seed-derived and individually grown tef plants were treated with foliar applications of the four CHAs (at four levels each) sprayed once at the early booting stage, and bagged to control cross pollination. Female fertility was assessed by recording seed set following controlled pollinations. Although all the CHAs caused some pollen sterility, their efficacy levels varied from 9.77 to 99.50% in treated plants compared to the control (6.68 +/- 1.04%). Pollen sterility increased with increasing CHA concentration. Near-complete pollen sterility (99.50 ± 0.50%) was achieved by the application of E4FO at rates of 1500 to 3000 ppm, and Ethrel at 5000 ppm. All the CHAs significantly reduced seed yield, with E4FO, Ethrel and Promalin ® at 5000 ppm causing the highest reduction, essentially yielding no seed. In the period following the application of the CHAs, plants treated with E4FO (1000 – 1500 ppm) exhibited stigmas that remained fertile. Hence, it is recommended that E4FO (at 1000 – 1500 ppm) can be used as a chemical emasculation agent for tef, with the least phytotoxicity and the highest female fertility. Key words: Eragrostis tef, Ethrel, ethyl4-florooxanilate, female fertility, gametocides, pollen sterility.

Improving field production of ergot alkaloids by application of gametocide on rye host plants

Ergot alkaloids are widely used in the pharmaceutical industry in drug preparations for treating migraines and Parkinson's disease, inducing uterine contraction, and other purposes. Phytopathogenic fungi of the genus Claviceps (e.g. C. purpurea) comprise a major biological source of ergot alkaloids. Worldwide industrial production of these alkaloids derives almost equally from two biotechnological procedures: submerged culture of the fungus in fermenters and field parasitic production in dormant fungal organs known as sclerotia (also termed ergot). Ergot yields from field cultivation are greatly affected by weather and also can be much reduced by pollen contamination from imperfectly male-sterile rye, as only unfertilized ovaries can be infected by C. purpurea spores. Two substances with gametocidal effect - maleic hydrazide and 2-chloroethylphosphonic acid - were tested during three consecutive seasons in small field experiments for the ability to induce or amplify the male sterility of rye as well as the impacts on germination of C. purpurea spores and general vitality of rye host plants. Maleic hydrazide was proven to be a highly effective gametocide on both a fertile rye variety and a variety with imperfectly induced cytoplasmic male sterility. It showed negligible effect on germination of C. purpurea spores. Both accurate dosaging of the active gametocidal compound and timing of the application just 2-3 weeks before onset of anthesis proved crucial to achieving high ergot yield with minimum grain impurities.

COULD ETHYLENE METABOLISM IN LEMON FRUIT INFLUENCE PETECA INCIDENCE?

Peteca of lemon is a postharvest physiological disorder resulting in the collapse of the oil glands. Subsequently, the oil leaks into the adjacent tissue and causes a darkened depression. The occurrence can be severe, without any specific pre- or postharvest practises to employ to reduce the incidence. Over several seasons the incidence of peteca was investigated to identify factors that influence the incidence of the disorder. The first observation was the highly erratic incidence between seasons as well as within an orchard in a season, with the early fruits being highly susceptible. In experiments to identify postharvest factors which influence the peteca incidence, 3 ppm ethylene and 5% CO2 were applied in a continuous flow-through system (20°C for 3 d). The CO2 treatment resulted in significantly higher incidence compared to the rest. Following on from these results, postharvest Ethephon (2-Chloroethyl phosphonic acid) (200 and 400 mg/L) and AVG (aminoethoxy-vinylglycine) (400 and 800 mg/L) applications to fruit resulted in a significant reduction in peteca. In the subsequent season, the same treatments were applied in an orchard one week before harvest and a similar reduction in peteca was recorded. Ethylene production from these fruits after harvest was measured and showed a transient spike in fruits from the Ethephon treatment. The results collected could indicate a protective action of ethylene in reducing rind sensitivity to peteca. It is hypothesised that if the internal ethylene synthesis is increased prior to harvest in sensitive fruit, i.e. immature fruit, a reduction in peteca can occur.

Effect of 2-chloroethylphosphonic acid and vanillin on chlorophyll, protein and RNA synthesis in detached cucumber cotyledons, and chlorophyll degradation in senescing leaf discs of kale

N<sup>6</sup>-benzylaminopurine (BAP) and KC1 stimulated growth in detached greening cucumber cotyledons; BAP enhanced RNA synthesis whereas KCl strikingly accelerated leucine-<sup>14</sup>C incorporation into proteins. Vanillin (0.01 M) inhibited greening and protein synthesis, and nullified the stimulatory effects of KC1. a-chloroethylphosphonic acid (CEPA, 0.01 M) inhibited greening without any effect on protein synthesis when it was applied alone; CEPA decreased RNA synthesis, completely nullified the K<sup>+</sup>-induced synthesis of chlorophyll, and reduced the BAP<sup>-</sup> or KCl<sup>-</sup>induced growth. Vanillin inhibited yellowing in 'senescing leaf discs of kale kept in darkness, whereas CEPA had an opposite effect.

The Influence of Ethephon Application Timing and Rate on Plant Growth, Yield, Tuber Size Distribution and Skin Color of Red LaSoda Potatoes

Optimizing the response of growth regulators depends in part on finding the most appropriate application rate and timing. Preliminary trials indicate that ethephon (2-chloroethylphosphonic acid) may be useful for improving potato (Solanum tuberosum L.) tuber appearance and skin color of red-skinned cultivars, but relatively little is known about optimum application practices. Two separate trials were conducted at the University of Idaho Parma Research and Extension Center to evaluate the effect of ethephon foliar application timing and rate on plant growth, tuber yield, size distribution, and skin color of the cultivar Red LaSoda. Skin color was rated visually and by colorimeter at harvest and periodically throughout storage at 4 °C. In 2011, ethephon application timing did not influence plant height, total yield, tuber size or skin color but did affect some tuber size classes. In contrast, all of these parameters were significantly influenced by application timing in 2012. The optimum application timing to influence skin color was a relatively narrow window during initial flower development, to 10 days after initial flowering (coinciding with tuber initiation). Increasing rates of ethephon significantly reduced plant height, increased foliar injury symptoms, and reduced average tuber size, but did not influence total yield in Red LaSoda. Higher ethephon rates resulted in significantly darker tuber skin (lower L* values) and increased red color (increased chroma and reduce hue angle values) when compared to the non-treated control. Evaluation of samples held in storage showed that differences in skin color ratings at harvest were maintained throughout the storage period. It is concluded that two foliar applications of ethephon at a rate between 292 and 438 ml ha−1applied ten days apart, initiated at pre-bloom, will provide the optimum change in skin color and reduce average tuber size without reducing total yield.

Hormonal regulation of gummosis and composition of gums from bulbs of hyacinth (Hyacinthus orientalis)

Hyacinth (Hyacinthus orientalis) bulbs infected by Fusarium oxysporum showed the symptoms of gummosis. The purpose of this study was to clarify the hormonal regulation of gummosis and composition of gums from hyacinth bulbs. The application of ethephon (2-chloroethylphosphonic acid), an ethylene-releasing compound, at 2% (w/w, in lanolin) induced gummosis in hyacinth bulbs. Methyl jasmonate (JA-Me) at 1.5% (w/w, in lanolin) induced gummosis as well. Simultaneous application of JA-Me and ethephon further enhanced gummosis. Molecular mass distribution of hyacinth gums analyzed by gel permeation chromatography indicated that the gums were mainly homogenous polysaccharides with an average molecular weight of ca. 30kDa. Analysis of the sugar composition of the gums after hydrolysis revealed that the majority were arabinose (ca. 35%) and galactose (ca. 40%) together with small amounts of fucose, rhamnose and uronic acids (ca. 5%, respectively), suggesting that the gums are pectic arabinogalactans. These results indicate that jasmonates (JAs) interact with ethylene to stimulate sugar metabolism, producing pectic arabinogalactans, and vice versa, leading to gummosis. These findings, together with those from our previous studies in tulips (Tulipa gesneriana) and grape hyacinth (Muscari armeniacum), revealed that sugar metabolism and hormonal regulation relating to gummosis are different among species of bulbous plants.

Heterologous hybridisation to a Pinus microarray: profiling of gene expression in Pinus radiata saplings exposed to ethephon

The design, construction and application of a Pinus microarray platform are described. The oligonucleotide microarray was developed using publicly available Pinus cDNA sequences mostly derived from Pinus taeda to test whether heterologous hybridisation of microarray probes will generate useful data when hybridised with cRNA constructed from the dominant New Zealand forestry species Pinus radiata. A comprehensive consensus sequence collection of Pinus cDNA sequences was collated into a non-redundant database used for automated design of 60-mer oligonucleotide microarray probes. The microarray slides, manufactured by Agilent Technologies (Palo Alto, California), were used to monitor gene expression in an induction experiment using 2-chloroethylphosphonic acid, common name ethephon and the active ingredient of the plant growth regulator Ethrel® (Bayer Crop Science). The transcriptomes from tissues of 2-year old Pinus radiata saplings +/− ethephon treatment were compared by hybridisation onto the Pinus microarray slides. Statistically significant differentially expressed genes identified by heterologous hybridisation to the Pinus microarray following ethephon induction included the up-regulation of genes in the xylem that were related to the metabolism of phenylpropanoids and flavonoids, and also defence responses, specifically against fungal/insect attack and oxidative stress. Bark, mucilaginous xylem and xylem generated largely mutually exclusive cohorts of genes and Gene Ontology (GO) classes. The results are also interpreted in reference to gross and microscopic morphological changes. Samples of gene responses were validated by quantitative RT-PCR. These results confirm the successful development of a Pinus microarray and demonstrate the utility of the microarray for transcriptomic research in Pinus radiata through heterologous hybridisation.

On the use of Ethephon as abscising agent in cv. Crimson Seedless table grape production: Combination of Fruit Detachment Force, Fruit Drop and metabolomics

The effect of 2-chloroethylphosphonic acid (Ethephon, in the following ETH) as abscising agent on cv. Crimson Seedless table grape was investigated by means of Fruit Detachment Force (FDF) and Fruit Drop (FD) analyses combined with a metabolomic study carried out by High Resolution Mass Spectrometry (HRMS) and Nuclear Magnetic Resonance (NMR) spectroscopy. The effectiveness of ETH as abscising agent was ascertained with ETH concentration ranging from 1.4 to 4.0g/L in a two-year study. The ETH treatments caused berry drops higher than 40% and induced an increase of tartaric acid, procyanidin P2, terpenoid derivatives and peonidin-3-glucoside as well as a decrease of catechin and epicatechin. HRMS–NMR covariance analysis was carried out to correlate the fluctuations of tartaric acid NMR signals to those of MS peaks of the secondary metabolites affected by ETH treatments.

IMPACT OF METAMITRON AS A THINNING COMPOUND ON APPLE PLANTS

Crop load regulation in modern apple fruit growing is an essential tool for obtaining regular and high quality yields. Common applied thinning products in Italy, such as naphthaleneacetic acid (NAA), naphtaleneacetamide (NAD), benzyladenine (BA), 2-chloroethylphosphonic acid (ethephon) and ammonium thiosulphate (ATS), do not always give satisfactory and consistent thinning results. Therefore, the interest farmers have in finding new thinning agents remains high. Within the present study, the impact of metamitron as a thinning compound was tested on 'Golden Delicious' CloneB Lb®, 'Golden Delicious' Reinders® and 'Fuji' KIKU®8 apple plants, in different open field trials. Results indicate that metamitron reduced fruit set in a concentration-dependent manner and highest abscission rates were encountered when thinning was conducted at 12 mm fruit diameter. Fruit drop increased generally in those plants, where leaf net photosynthesis was strongly inhibited by metamitron. At the same time, an increase in leaf chlorophyll fluorescence of photosystem I was detected. Maximum photosynthetic stress levels were recorded approximately 6 days after application, whereas a complete recovering occurred within 3-4 weeks. Fruit quality parameters such as fruit size, fruit color, soluble solid content, and titratable acidity were improved by metamitron. Fruit russeting remained unaltered, besides some leaf phytotoxic effects compared to treated plants. So far, only the poor return bloom remains a concern. To sum up, the present study shows that metamitron would represent a very promising and powerful tool for regulating apple crop load.