Reversible Inhibition of Tomato Fruit Gene Expression at High Temperature (Effects on Tomato Fruit Ripening)

Abstract

caused by alterations in gene expression (Mansson et al., 1985). %ter et al. (1985) identified 19 different mRNA families that were present in ripe fruit but were undetectable or present at a much reduced level in unripe fruit. A number of cDNA clones prepared from these "As have been identified and thereby linked to ripening-related physiological changes. pTOM13 has been identified as a an enzyme that catalyzes the last step in the ethylene synthesis pathway. pTOM6 encodes for PG, an enzyme that depolymerizes pectins in the fruit cell wall (Grierson et 1986)' Phytoene 'ynthase, an enzyme in the pathway Of lycopene synthesist has been identified with pToM5 (Fray and Grierson, 1993). These clones have Provided a useful means to examine different factors that influence the ripening process.Short exposures to temperatures above 35°C have been found to inhibit fruit ripening reversibly (Biggs et al., 1988;Lurie and Klein, 1990), whereas fruit held for extended periods at high temperature ripen abnormally (ogura et al., 1975). rn tomatoes, elevated temperatures inhibit ethylene synthesis (Biggs et al,, 1988) and PG accumulation (Yoshida et al., 1984) and interfere with lycopene synthesis (Ogura et al., 1975). Some of these effects have been attrib-(Ogura et al.r 1975)r but and Grierson (1988) demonstrated that inhibition also occurred at the level of gene expression. If the inhibitory effect of high temperature is reversible, then fruit subjected to a heat stress might ripen normally but more slowly than unheated fruit. This was ened more slowly than unheated fruit (~~~i and Klein, were not investigated.Tomato fruit are chilling sensitive and have reduced storage life and decreased ability to ripen when stored at temperatures below 10°C; the degree of damage is related to the length of time at a particular temperature. Chilling injury could be reduced in temperature-sensitive tissues by modifying the pattern of temperature exposure, e.g. periodically warming the chilled tissue above the chillAbbreviations: HSP, heat-shock protein; PG, polygalacturonase.The reversible inhibition of three ripening-related processes by high-temperature treatment (38°C) was examined i n tomato (Lycopersicon esculentum 1. cv Daniella) fruit. Ethylene production, color development, and softening were inhibited during heating and recovered afterward, whether recovery took place at 20°C or fruit were first held at chilling temperature (2OC) after heating and then daced at 2ooc* Ethylene production and colar development proceeded normally in heated fruit after 14 d of chilling, whereas the unheated fruit had delayed ethylene production and uneven color development. Levels of mRNA for 1 -aminocyclopropane-1 -carboxylic acid oxidase, phytoene synthase, and polygalacturonase decreased dramatically during the heat treatment but recovered afterward, whereas the mRNA for HSPl7 increased during the high-temperature treatment and then decreased when fruit were removed from heat. As monitored by western blots, the HSp17 protein disappeared from frui...

Armazenamento de tomate cultivar "Cronus" em função do estádio de maturação e da temperatura

“…Os resultados obtidos concordam com LURIE et al (1996), SABEHAT et al (1996) A incidência de podridões foi menor nos frutos armazenados no estádio de maturação parcialmente maduro e nas temperaturas de 10 e 12ºC. De acordo com WILLS et al (1981), frutos imaturos são menos suscetíveis à ocorrência de podridões que frutos maduros, concordando com os resultados obtidos neste trabalho.…”

“…O amadurecimento do tomate envolve uma série de Ciência Rural, v.37, n.5, set-out, 2007. eventos fisiológicos coordenados que desencadeiam mudanças na pigmentação, no sabor, na firmeza de polpa e no aroma, sendo altamente influenciados pela temperatura à qual os frutos estão expostos (LURIE et al, 1996). MOURA et al (1999) citam que a qualidade do tomate é definida por estas mudanças decorrentes do amadurecimento, sendo a firmeza de polpa o aspecto mais importante (DE KETELAERE et al, 2004).…”

Spermidine affects the transcriptome responses to high temperature stress in ripening tomato fruit

“…The ripening process of tomato fruit involves a complex and coordinated series of changes in pigmentation, flavor, texture, and aroma resulting from physiological and biochemical activities, which were caused by alterations in gene expression (Lurie et al, 1996). HT has been found to inhibit ethylene synthesis and proteoglycan accumulation, to interfere with lycopene synthesis, and finally to inhibit fruit ripening.…”

“…Furthermore, heat treatment leads to an inhibition of expression of tomato-ripening genes and thus has a negative impact on fruit quality (Picton and Grierson, 1988). The mRNA levels of 1-aminocyclopropane-1-carboxylic acid oxidase, phytoene synthase, and polygalacturonase decreased dramatically during the heat treatment but recovered afterwards, whereas the mRNA of heat shock protein (HSP) 17 increased during the HT treatment and then decreased when fruits were removed from heat stress (Lurie et al, 1996). So the inhibition of fruit ripening by HT might occur at the level of gene expression.…”

Comportamento pós-colheita das características químicas, bioquímicas e físicas de frutos de tomateiros heterozigotos nos locos alcobaça e ripening inhibitort

“…O complexo processo de maturação dos frutos é controlado geneticamente e coordenado por uma série de alterações fisiológicas e bioquímicas que afetam principalmente o sabor, odor, cor e textura (Lurie et al, 1996), que tornam o fruto aceitável para o consumo. O amadurecimento caracteriza-se por uma seqüência de alterações sincronizadas e evidenciadas por mudanças na taxa respiratória, produção de etileno, síntese de carotenóides, desenvolvimento de "flavor", alteração na textura (Lobo, 1981), degradação da clorofila, produção de açúcares, alteração no metabolismo de ácidos orgânicos e amidos, aumento na atividade de enzimas pectolíticas, maturação das sementes (Tigchelaar et al, 1978), que ocorrem em um período relativamente curto.…”