Differential effects of low-temperature inhibition on the propylene induced autocatalysis of ethylene production, respiration and ripening of 'Hayward' kiwifruit

Previous studies (Stavroulakis and Sfakiotakis, 1993) have shown an inhibition of propylene-induced ethylene production in kiwifruit below a critical temperature range of 11-14.8 degrees C. The aim of this research was to identify the biochemical basis of this inhibition in kiwifruit below 11-14.8 degrees C. 'Hayward' kiwifruit were treated with increasing propylene concentrations at 10 and 20 degrees C. Ethylene biosynthesis pathways and fruit ripening were investigated. Kiwifruit at 20 degrees C in air started autocatalysis of ethylene production and ripened after 19 d with a concomitant increase in respiration. Ethylene production and the respiration rise appeared earlier with increased propylene concentrations. Ripening proceeded immediately after propylene treatment, while ethylene autocatalysis needed a lag period of 24-72 h. The latter event was attributed to the delay found in the induction of 1-aminocyclopropane-1-carboxylate synthase (ACC synthase) activity and consequently to the delayed increase of l-aminocyclopropane l-carboxylic acid (ACC) content. In contrast propylene treatment induced 1-aminocyclopropane-1-carboxylate oxidase (ACC oxidase) activity with no lag period. Moreover, transcription of ACC synthase and ACC oxidase genes was active only in ethylene-producing kiwifruit at 20 degrees C. In contrast, treatment at 10 degrees C with propylene strongly inhibited ethylene production, which was attributed to the low activities of both ACC synthase and ACC oxidase as well as the low initial ACC level. Interestingly, fruit treated with propylene at 10 degrees C appeared to be able to transcribe the ACC oxidase but not the ACC synthase gene. However, propylene induced ripening of that fruit almost as rapidly as in the propylene-treated fruit at 20 degrees C. Respiration rate was increased together with propylene concentration. It is concluded that kiwifruit stored at 20 degrees C behaves as a typical climacteric fruit, while at 10 degrees C behaves like a non-climacteric fruit. We propose that the main reasons for the inhibition of the propylene induced (autocatalytic) ethylene production in kiwifruit at low temperature (less than or equal to 10 degrees C), are primarily the suppression of the propylene-induced ACC synthase gene expression and the possible post-transcriptional modification of ACC oxidase.

Differential effects of low-temperature inhibition on the propylene induced autocatalysis of ethylene production, respiration and ripening of 'Hayward' kiwifruit

Previous studies (Stavroulakis and Sfakiotakis, 1993) have shown an inhibition of propylene-induced ethylene production in kiwifruit below a critical temperature range of 11-14.8 degrees C. The aim of this research was to identify the biochemical basis of this inhibition in kiwifruit below 11-14.8 degrees C. 'Hayward' kiwifruit were treated with increasing propylene concentrations at 10 and 20 degrees C. Ethylene biosynthesis pathways and fruit ripening were investigated. Kiwifruit at 20 degrees C in air started autocatalysis of ethylene production and ripened after 19 d with a concomitant increase in respiration. Ethylene production and the respiration rise appeared earlier with increased propylene concentrations. Ripening proceeded immediately after propylene treatment, while ethylene autocatalysis needed a lag period of 24-72 h. The latter event was attributed to the delay found in the induction of 1-aminocyclopropane-1-carboxylate synthase (ACC synthase) activity and consequently to the delayed increase of l-aminocyclopropane l-carboxylic acid (ACC) content. In contrast propylene treatment induced 1-aminocyclopropane-1-carboxylate oxidase (ACC oxidase) activity with no lag period. Moreover, transcription of ACC synthase and ACC oxidase genes was active only in ethylene-producing kiwifruit at 20 degrees C. In contrast, treatment at 10 degrees C with propylene strongly inhibited ethylene production, which was attributed to the low activities of both ACC synthase and ACC oxidase as well as the low initial ACC level. Interestingly, fruit treated with propylene at 10 degrees C appeared to be able to transcribe the ACC oxidase but not the ACC synthase gene. However, propylene induced ripening of that fruit almost as rapidly as in the propylene-treated fruit at 20 degrees C. Respiration rate was increased together with propylene concentration. It is concluded that kiwifruit stored at 20 degrees C behaves as a typical climacteric fruit, while at 10 degrees C behaves like a non-climacteric fruit. We propose that the main reasons for the inhibition of the propylene induced (autocatalytic) ethylene production in kiwifruit at low temperature (less than or equal to 10 degrees C), are primarily the suppression of the propylene-induced ACC synthase gene expression and the possible post-transcriptional modification of ACC oxidase.

Synthesis of indium nanoparticles at ambient temperature; simultaneous phase transfer and ripening

The synthesis of size-monodispersed indium nanoparticles via an innovative simultaneous phase transfer and ripening method is reported. The formation of nanoparticles occurs in a one-step process instead of well-known two-step phase transfer approaches. The synthesis involves the reduction of InCl3 with LiBH4 at ambient temperature and although the reduction occurs at room temperature, fine indium nanoparticles, with a mean diameter of 6.4 ± 0.4 nm, were obtained directly in non-polar n-dodecane. The direct synthesis of indium nanoparticles in n-dodecane facilitates their fast formation and enhances their size-monodispersity. In addition, the nanoparticles were highly stable for more than 2 months. The nanoparticles were characterised by dynamic light scattering (DLS), small angle X-ray scattering (SAXS), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and Fourier transform infrared (FT-IR) spectroscopy to determine their morphology, structure and phase purity.

Linking thermal imaging to physiological indicators in Carica papaya L. under different watering regimes

Water deficit is the most limiting factor for yield and fruit-quality parameters in papaya crop (Carica papaya L.), deficit-irrigation (DI) strategies offering a feasible alternative to manage limiting water resources. When DI is applied, it is crucial to assess the physiological status of the crop in order to maintain the plant within a threshold value of water stress so as no to affect yield or fruit-quality parameters. The aim of this work was to evaluate the feasibility of thermal imaging in young papaya plants to assess the physiological status of this crop when it is subjected to different DI regimes, studying the relationships between the changes in leaf temperature (Tleaf) and in the major physiological parameters (i.e., stomatal conductance to water vapor, gs; transpiration, E; and net photosynthesis, An). The trial was conducted in a greenhouse from March to April of 2012. Plants were grown in pots and subjected to four irrigation treatments: (1) a full irrigation treatment (control), maintained at field capacity; (2) a partial root-zone drying treatment, irrigated with 50% of the total water applied to control to only one side of roots, alternating the sides every 7 days; (3) a regulated deficit irrigation (50% of the control, applied to both sides of plant); (4) and a non-irrigated treatment, in which irrigation was withheld from both sides of the split root for 14 days, followed by full irrigation until the end of the study. Significant relationships were found between Tleaf and major physiological variables such as gs, E and An. Additionally, significant relationships were found between the difference of leaf-to-air temperature (ΔTleaf–air) and gas-exchange measurements, which were used to establish the optimum range of ΔTleaf–air as a preliminary step to the crop-water monitoring and irrigation scheduling in papaya, using thermal imaging as the main source of information. According to the results, we conclude that thermal imaging is a promising technique to monitor the physiological status of papaya during drought conditions.

Linking thermal imaging to physiological indicators in Carica papaya L. under different watering regimes

Water deficit is the most limiting factor for yield and fruit-quality parameters in papaya crop (Carica papaya L.), deficit-irrigation (DI) strategies offering a feasible alternative to manage limiting water resources. When DI is applied, it is crucial to assess the physiological status of the crop in order to maintain the plant within a threshold value of water stress so as no to affect yield or fruit-quality parameters. The aim of this work was to evaluate the feasibility of thermal imaging in young papaya plants to assess the physiological status of this crop when it is subjected to different DI regimes, studying the relationships between the changes in leaf temperature (Tleaf) and in the major physiological parameters (i.e., stomatal conductance to water vapor, gs; transpiration, E; and net photosynthesis, An). The trial was conducted in a greenhouse from March to April of 2012. Plants were grown in pots and subjected to four irrigation treatments: (1) a full irrigation treatment (control), maintained at field capacity; (2) a partial root-zone drying treatment, irrigated with 50% of the total water applied to control to only one side of roots, alternating the sides every 7 days; (3) a regulated deficit irrigation (50% of the control, applied to both sides of plant); (4) and a non-irrigated treatment, in which irrigation was withheld from both sides of the split root for 14 days, followed by full irrigation until the end of the study. Significant relationships were found between Tleaf and major physiological variables such as gs, E and An. Additionally, significant relationships were found between the difference of leaf-to-air temperature (ΔTleaf–air) and gas-exchange measurements, which were used to establish the optimum range of ΔTleaf–air as a preliminary step to the crop-water monitoring and irrigation scheduling in papaya, using thermal imaging as the main source of information. According to the results, we conclude that thermal imaging is a promising technique to monitor the physiological status of papaya during drought conditions.

The mitochondrial elongation factor LeEF-Tsmt is regulated during tomato fruit ripening and upon wounding and ethylene treatment.

A gene encoding an elongation factor LeEF-Tsmt that participates in the protein synthesis process in mitochondria shows strong expression in ripening fruit as compared to other organs. It is strongly up-regulated during the first stages of the ripening process in parallel with the climacteric rise in respiration. LeEF-Tsmt expression is stimulated by ethylene, wounding and high temperature but ethylene-insensitive mutants exhibit normal expression. Transgenic fruit have been generated in which LeEF-Tsmt has been constitutively up- and down-regulated. Surprisingly, altering the expression of the gene by genetic transformation with antisense and sense LeEF-Tsmt constructs did not affect the pattern of respiration and ethylene production during ripening and upon wounding. In addition, expression of the alternative oxidase gene which is known to play an important role in respiratory climacteric was not affected. Possible reasons for the absence of effect on respiration of variations of LeEF-Tsmt gene expression are discussed.

Influence Of The Stage Of Ripeness On The Composition Of Iridoids And Phenolic Compounds In Genipap (genipa Americana L.).

Genipap fruits, native to the Amazon region, were classified in relation to their stage of ripeness according to firmness and peel color. The influence of the part of the genipap fruit and ripeness stage on the iridoid and phenolic compound profiles was evaluated by HPLC-DAD-MS(n), and a total of 17 compounds were identified. Geniposide was the major compound in both parts of the unripe genipap fruits, representing >70% of the total iridoids, whereas 5-caffeoylquinic acid was the major phenolic compound. In ripe fruits, genipin gentiobioside was the major compound in the endocarp (38%) and no phenolic compounds were detected. During ripening, the total iridoid content decreased by >90%, which could explain the absence of blue pigment formation in the ripe fruits after their injury. This is the first time that the phenolic compound composition and iridoid contents of genipap fruits have been reported in the literature.

Utilização de 1-metilciclopropeno e resfriamento rápido na conservação de pêssegos

Postharvest losses vary among the different vegetable products. However, among fruits and vegetables the losses generally range from 30% to 50%. Thus, this paper aimed the application of 1-methylcycloprene (1-MCP) and fast cooling with forced air (PC) on peaches, in order to estimate their effects in the ripening process of this fruit. Physiological analyses were performed, such as loss of fresh mass, firmness, pH, titratable acidity, soluble solids, ratio and CO2 production, as well as sensorial analyses such as color, texture and flavor. The experiment was divided in two phases. In the first one, concentrations of 30, 60, and 90 nL/L 1-MCP, applied at 0 ºC and 20 ºC, were tested. The fruits treated without 1-MCP were denominated control for both temperatures studied. The second phase was composed by the following treatments: cold storage (CS) or control, cooling with forced air (CFA), cooling with forced air followed by 1-MCP application (CFA + 1-MCP) and 1-MCP application (1-MCP). Among these, the CFA + 1-MCP treatment provided more firmness of the fruits in comparison to the control fruits. The respiratory rate of peaches under CFA and CFA + 1-MCP treatments decreased in comparison to the control fruit respiratory rates.

Condições de atmosfera controlada para pêssegos "maciel" colhidos em dois estádios de maturação

O objetivo deste trabalho foi avaliar o efeito de duas temperaturas e condições de atmosfera controlada (AC) sobre a conservação de pêssegos da cultivar Maciel, colhidos em dois estádios de maturação. Os tratamentos avaliados foram: armazenamento refrigerado (AR) na temperatura de +0,5°C; AR na temperatura de -0,5°C; 2,0kPa O2 + 4,0kPa CO2 em -0,5°C; 1,0kPa O2 + 3,0kPa CO2 em -0,5°C; 2,0kPa O2 + 6,0kPa CO2 em -0,5°C. As avaliações foram realizadas após 60 dias de armazenamento e mais dois e quatro dias de exposição dos frutos à temperatura de 20ºC. Na análise realizada após dois meses de armazenamento, mais dois dias a 20°C, verificou-se que os frutos submetidos a 2,0kPa de O2 + 4,0 kPa de CO2 apresentaram maior firmeza de polpa em relação aos demais tratamentos, sendo que a mesma não foi influenciada pelo estádio de maturação. Os sólidos solúveis totais foram maiores em frutos com estádio de maturação maduro independente da condição de armazenamento. A ocorrência de podridões e escurecimento interno da polpa não foi influenciada pelo estádio de maturação. No entanto, a condição de AC de 1,0 kPa de O2 + 3,0kPa de CO2 proporcionou o menor percentual de podridões e escurecimento interno da polpa em relação aos demais tratamentos. Na avaliação realizada aos quatro dias de exposição a 20°C, os frutos colhidos no estádio maduro estavam completamente podres, independente da condição de armazenamento praticada.

Previsão de bitter pit em maçãs por meio da infiltração de Mg2+ e da aplicação de ethephon nos frutos

Estudou-se o efeito da infiltração de magnésio e cálcio no desenvolvimento de sintomas de bitter pit de maçãs 'Gala'. Examinou-se, também, a eficiência da infiltração de magnésio e da aceleração da maturação de maçãs 'Royal Gala' como métodos de previsão da ocorrência de bitter pit após o armazenamento. No primeiro experimento, maçãs 'Gala' foram infiltradas com MgCl2; CaCl2 ou MgCl2 mais CaCl2. No segundo experimento, maçãs 'Royal Gala' foram infiltradas com MgCl2; ou imersas em solução contendo ethephon por cinco minutos. Como controle, frutos de cada cultivar foram armazenados em atmosfera controlada por seis meses mais 18 dias a 20°C. Frutos infiltrados com MgCl2 apresentaram significativo acréscimo na incidência e severidade de bitter pit, proporcional à concentração de MgCl2 na solução. Frutos infiltrados com CaCl2 não apresentaram sintomas de bitter pit. A aceleração da maturação de maçãs 'Royal Gala' na colheita foi efetiva na previsão de bitter pit após o armazenamento.

Method for early quantification of quiescent infections of Colletotrichum musae on bananas

Introduction. This protocol aims at detecting and quantifying quiescent infections of Colletotrichum musae on bananas. The principle, key advantages, starting plant material, time required and expected results are presented. Materials and methods. The materials required and details of the three steps of the protocol (fruit sampling, fruit ripening and anthracnose lesion quantification) are described. Possible troubleshooting is discussed. Results. The protocol results in the quantification of anthracnose lesions on the fruits, which makes it possible to predict postharvest losses due to anthracnose (peel rot), and also to propose a better management of postharvest fungicide applications.

Mechanical characterisation of banana fruits

Introduction. This protocol aims at measuring the mechanical characteristics of bananas, especially peel and fruit hardness, and pulp firmness; it can also allow the mechanical characterisation of green or ripening fruit of different pedo-climatic origins and/or varieties. Materials and methods. This part describes the required laboratory materials and the three steps necessary for the measurement of the mechanical characteristics of bananas. Results. The data allow the drawing of a curve characterising the firmness of the fruit (slope), hardness of the peel (peak) and hardness of the pulp (plateau).

Total Soluble Solids from Banana: Evaluation and Optimization of Extraction Parameters

Banana, an important component in the diet of the global population, is one of the most consumed fruits in the world. This fruit is also very favorable to industry processes (e. g., fermented beverages) due to its rich content on soluble solids and minerals, with low acidity. The main objective of this work was to evaluate the influence of factors such as banana weight and extraction time during a hot aqueous extraction process on the total soluble solids content of banana. The extract is to be used by the food and beverage industries. The experiments were performed with 105 mL of water, considering the moisture of the ripe banana (65%). Total sugar concentrations were obtained in a beer analyzer and the result expressed in degrees Plato (degrees P, which is the weight of the extract or the sugar equivalent in 100 g solution at 20 degrees C), aiming at facilitating the use of these results by the beverage industries. After previous studies of characterization of the fruit and of ripening performance, a 2(2) full-factorial star design was carried out, and a model was developed to describe the behavior of the dependent variable (total soluble solids) as a function of the factors (banana weight and extraction time), indicating as optimum conditions for extraction 38.5 g of banana at 39.7 min.

New species of Anastrepha Schiner (Diptera, Tephritidae) from remnant area of the Atlantic Rain Forest and surroundings in the state of Espirito Santo, Brazil

Four new species of Anastrepha Schiner were collected in McPhail-type traps hung in trees in a natural reserve and in commercial papaya orchards in Linhares, Espirito Santo state, Brazil. They are described and named herein as follows: Anastrepha atlantica n. sp., Anastrepha glochin n. sp., Anastrepha linharensis n. sp. and Anastrepha martinsi n. sp. Only the latter was collected in traps hung in papaya orchards. The classification of these species in species groups of Anastrepha is also discussed.

Tree performance and fruit yield and quality of `Okitsu` Satsuma mandarin grafted on 12 rootstocks

The citriculture in Brazil, as well as in other important regions in the world, is based on very few mandarin cultivars. This fact leads to a short harvest period and higher prices for off-season fruit. The `Okitsu` Satsuma (Citrus unshiu Marc.) is among the earliest ripening mandarin cultivars and it is considered to be tolerant to, citrus canker (Xanthomonas citri subsp. citri Schaad et al.) and to citrus variegated chlorosis (Xylella fastidiosa Wells et al.). Despite having regular fruit quality under hot climate conditions, the early fruit maturation and absence of seeds of `Okitsu` fruits are well suited for the local market in the summer(December through March), when the availability of citrus fruits for fresh consumption is limited. Yet, only a few studies have been conducted in Brazil on rootstocks for `Okitsu`. Consequently, a field trial was carried out in Bebeclouro, Sao Paulo State, to evaluate the horticultural performance of `Okitsu` Satsuma mandarin budded onto 12 rootstocks: the citrandarin `Changsha` mandarin (Citrus reticulata Blanco) x Poncirus trifoliata `English Small`: the hybrid Rangpur lime (Citrus limonia Osbeck) x `Swingle` citrumelo (P. trifoliata (L.) Raf. x Citrus paradisi Macfad.); the trifoliates (P. trifoliata (L) Raf)`Rubidoux`,`FCAV` and `Flying Dragon`(P. trifoliata var. monstrosa); the mandarins `Sun Chu Sha Kat`(C. reticulata Blanco) and `Sunki`(Citrus sunki (Hayata) Hort. ex. Tanaka); the Rangpur limes (C. limonia Osbeck) `Cravo Limeira` and `Cravo FCAV`;`Carrizo` citrange (Citrus sinensis x P. trifoliata), `Swingle` citrumelo (P. trifoliata x C. paradisi), and `Orlando` tangelo (C. paradisi x Citrus tangerina cv. `Dancy`). The experimental grove was planted in 2001, using a 6 m x 3 m spacing, in a randomized block design. No supplementary irrigation was applied. Fruit yield, canopy volume, and fruit quality were assessed for each rootstock. A cluster multivariate analysis identified three different rootstock pairs with similar effects on plant growth, yield and fruit quality of `Okitsu` mandarin. The `Flying Dragon `trifoliate had a unique effect over the `Okitsu` trees performance, inducing lower canopy volume and higher yield efficiency and fruit quality, and might be suitable for high-density plantings. The `Cravo Limeira` and `Cravo FCAV` Rangpur limes induced early-ripening of fruits, with low fruit quality. `Sun Chu Sha Kat` and `Sunki` mandarins and the `Orlando` tangelo conferred lower yield efficiency and less content of soluble solids for the latter rootstock. (C) 2009 Elsevier B.V. All rights reserved.