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Tropospheric ozone (O3) is believed to be the most important phytotoxic air pollutant in industrialised countries and one of the major anthropogenic stresses that threaten native and cultivated ecosystems. Although reactive oxygen species (ROS) generated following O3 exposure are believed to act as key molecules that elicit plant response to O3, the current information underlines the importance of the complex interactions between ROS and several phytohormones, among which ethylene (ET) (Kangasjärvi . 2005, Diara 2005).

Plants’ exposure to ozone (O3) activates a multitude of defense reactions – among which the launch of a cell death program (PCD) leading to the development of visible foliar symptoms – which are also deployed in response to other abiotic or biotic stressors. Ethylene (ET) plays a key role in these events.

High ethylene (ET) synthesis observed under stress conditions produces stoichiometric amounts of CNand CO2. Normally, plant tissues have ample capacity to detoxify the cytosolic CN??to β-cyanoalanine by the action of β-cyanoalanine synthase (β-CAS), mainly present in the mitochondrial fraction.

Physical stresses such as shock and vibration deteriorate the quality of fresh fruits and vegetables not only by direct physical damage but also through the endogenous biological activities of the produce. Ethylene seems to be the most important factor of the stress response in the produce. In this paper we study the effects of slight dropping (1, 3, 10 times) on the ethylene and CO2 production of the whole tomato fruits and accumulation of the ACC synthase (ACS) mRNA in the tissue. The mature green tomato () fruits which were screened by ethylene production rate (less than 0.2 μlkg??h??) were used to avoid a contamination of climacteric phase fruit.

We present a new approach to study the pathogen-host interaction by online monitoring of ethylene release using a laser-based photoacoustic detector. The instrument allows detection of ethylene emission in a continuous flow system down to 10 pptv (pptv = parts-per-trillion volume, 1:1012) (Bijnen ., 1996) and has relatively high time resolution for measuring the dynamics of ethylene production by and by infected tomatoes. Moreover, it has been proved to be a powerful tool to study the relationship between ethylene released by the fungus and the enhanced ethylene production in infected tomato with respect to disease development.

Cadmium is a highly toxic heavy metal for all living organisms and causes a reduction of several physiological processes in plants. Cadmium tends to accumulate in several crops grown in soils containing Cd (Grant ., 1998). Grain and cereal products are primary sources of Cd, being able to accumulate Cd in grain (Greger and Löfstedt, 2004). Ethylene production has been often associated with response to Cd exposure in several species (Rodecap and Tingery, 1981; Bhattacharjee, 1997).

Dicotyledonous plants need to reduce Fe(III) to Fe(II), mediated by a ferric reductase (encoded by the gene in ), prior to its uptake through an Fe(II) transporter (encoded by the gene in ). The expression of both genes is up-regulated under Fe deficiency. In the last years evidence has been presented to support a role for ethylene as activator of the ferric reductase activity but it is not known whether ethylene affects transcription or other aspects of this activity (Romera and Alcántara, 2004).

The control of the ripening process in climacteric fruit mainly relies on the possibility of affecting ethylene biosynthesis and action. This can be achieved through genetic manipulation, by modulating environmental parameters (temperature, atmosphere composition) during storage, or using specific inhibitors of ethylene biosynthesis/perception. The effects of treatments with ethylene inhibitors on climacteric fruit, however, differ according to several factors including genotype.

1-Methylcyclopropene (1-MCP) is an inhibitor of ethylene binding that can prevent ethylene-dependent responses in many fruits and vegetables (Blankenship and Dole, 2003; Watkins, 2006). 1-MCP has been commercialized as SmartFresh and food use registration has been obtained for a wide range of crops in several countries (Watkins, 2006).

The ripening of fleshy fruit is generally distinguished into two categories, climacteric and non-climacteric, based on the fruit’s ability to produce or ethylene in high concentrations during maturation. A gaseous hormone produced by higher plants, ethylene regulates a number of physiological processes ranging from fruit development to maturation and senescence (Yang and Hoffmann 1984; Giovannoni 2004).