Publications by authors named "Michal Oren-Shamir"

Tuta absoluta ("leafminer"), is a major pest of tomato crops worldwide. Controlling this insect is difficult due to its efficient infestation, rapid proliferation, and resilience to changing weather conditions. Furthermore, chemical pesticides have only a short-term effect due to rapid development of T.

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Phenylalanine has a unique role in plants as a source of a wide range of specialized metabolites, named phenylpropanoids that contribute to the adjustment of plants to changing developmental and environmental conditions. The profile of these metabolites differs between plants and plant organs. Some of the prominent phenylpropanoids include anthocyanins, phenolic acids, flavonoids, tannins, stilbenes, lignins, glucosinolates and benzenoid phenylpropanoid volatiles.

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Cold is the best means of prolonging fruit storage. However, tropical fruit are susceptible to cold storage. The mode of action of mango fruit tolerance to suboptimal cold temperature of 7 or 10 °C after postharvest application of 8 mM phenylalanine was investigated using transcriptomic and metabolomic analyses of mango fruit during suboptimal cold storage.

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Elicitation treatments of grape cell cultures with methyl jasmonate (MeJA), ultraviolet-C (UV-C) irradiation, and sucrose induce mild production of stilbenes and flavonoids due to limited substrate availability. However, these treatments cause a synergistic boost of stilbenes production when applied to two phenylalanine (Phe)-enriched transgenic grape cell lines, * + and * + . The combined treatment of UV-C elicitation on the Phe-fed * + line resulted in the highest content of stilbenes (37.

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Anthocyanins are secondary metabolites responsible for the red coloration of mango and apple. The red color of the peel is essential for the fruit's marketability. Anthocyanins and flavonols are synthesized via the flavonoid pathway initiated from phenylalanine (Phe).

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Stilbenes and flavonoids are two major health-promoting phenylpropanoid groups in grapes. Attempts to promote the accumulation of one group usually resulted in a decrease in the other. This study presents a unique strategy for simultaneously increasing metabolites in both groups in cv.

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Stilbenes are phytoalexins with health-promoting benefits for humans. Here, we boost stilbenes' production, and in particular the resveratrol dehydrodimer viniferin, with significant pharmacological properties, by overexpressing () under unlimited phenylalanine (Phe) supply. cell cultures were co-transformed with a feedback-insensitive DAHP synthase (*) and genes, under constitutive promoters.

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Mango fruit exposed to sunlight develops red skin and are more resistant to biotic and abiotic stresses. Here we show that harvested red mango fruit that was exposed to sunlight at the orchard is more resistant than green fruit to Colletotrichum gloeosporioides. LCMS analysis showed high amounts of antifungal compounds, as glycosylated flavonols, glycosylated anthocyanins, and mangiferin in red vs.

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Lisianthus (Eustoma grandiflorum), a leading plant in the cut flower industry, is scentless. Here we show that lisianthus flowers have potential to produce several fragrant benzenoid-phenylpropanoids when substrate availability is not limited. To enable hyperaccumulation of substrates for the production of volatile benzenoid-phenylpropanoids, lisianthus commercial hybrid "Excalibur Pink" was transformed via floral dipping with a feedback-insensitive Escherichia coli DAHP synthase (AroG*) and Clarkia breweri benzyl alcohol acetyltransferase (BEAT), under constitutive promoters.

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Flowers are the most vulnerable plant organ to infection by the necrotrophic fungus Botrytis cinerea. Here we show that pre-treatment of chrysanthemum (Chrysanthemum morifolium) flowers with phenylalanine (Phe) significantly reduces their susceptibility to B. cinerea.

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More than 40% of harvested fruit is lost, largely due to decay. In parallel, restrictions on postharvest fungicides call for eco-friendly alternatives. Fruit's natural resistance depends mainly on flavonoids and anthocyanins-which have antioxidant and antifungal activity-synthesized from the phenylpropanoid pathway with phenylalanine as a precursor.

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Botrytis cinerea is a major plant pathogen, causing losses in crops during growth and storage. Here we show that increased accumulation of phenylalanine (Phe) and Phe-derived metabolites in plant leaves significantly reduces their susceptibility to B. cinerea.

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Fruit defense against pathogens relies on induced and preformed mechanisms. The present contribution evaluated performed resistance of red and green mango fruit against the fungal pathogen Colletotrichum gloeosporioides and identified the main active antifungal components. High-performance liquid chromatography analysis of nonhydrolyzed mango peel extracts identified major anthocyanin peaks of glycosylated cyanidin and methylcyanidin, and flavonol peaks of glycosylated quercetin and kaempferol, which were more abundant on the 'red side' of red mango fruit.

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Ethylene plays a major role in the regulation of flower senescence, including in the ethylene-sensitive 'Sansai Blue' orchid flowers. This cut flower is popular in Thailand due to its light blue big size florets possessing a beautiful shape pattern. In the present study, we further examined the rapid ethylene-induced process of active anthocyanin degradation in cut 'Sansai Blue' flowers, which occurred much before detection of other typical senescence-related symptoms.

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Growth in hot climates selectively alters potato tuber secondary metabolism-such as the anthocyanins, carotenoids, and glycoalkaloids-changing its nutritive value and the composition of health-promoting components. Potato breeding for improved nutritional value focuses mainly on increasing the health-promoting carotenoids and anthocyanins, and controlling toxic steroidal glycoalkaloids (SGAs). Metabolite levels are genetically determined, but developmental, tissue-specific, and environmental cues affect their final content.

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The adaptation of the Agrobacterium-mediated floral-dipping technique is limited, to date, to a small number of plants. In this paper, we present the efficient transformation of one of the leading plants in the cut flower industry, lisianthus (Eustoma grandiflorum). This method is approximately 18 months shorter than the known tissue culture-based transformation.

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Phenylalanine (Phe) is a precursor for a large group of plant specialized metabolites, including the fragrant volatile benzenoid-phenylpropanoids (BPs). In plants, the main pathway leading to production of Phe is arogenate, while the pathway phenylpyruvate (PPY) is considered merely an alternative route. Unlike plants, in most microorganisms the only pathway leading to the synthesis of Phe is PPY.

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Plants produce a diverse repertoire of specialized metabolites that have multiple roles throughout their life cycle. Some of these metabolites are essential components of the aroma and flavor of flowers and fruits. Unfortunately, attempts to increase the yield and prolong the shelf life of crops have generally been associated with reduced levels of volatile specialized metabolites and hence with decreased aroma and flavor.

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In contrast to the detailed molecular knowledge available on anthocyanin synthesis, little is known about its catabolism in plants. Litchi (Litchi chinensis) fruit lose their attractive red color soon after harvest. The mechanism leading to quick degradation of anthocyanins in the pericarp is not well understood.

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Environmental stresses such as high light intensity and temperature cause induction of the shikimate pathway, aromatic amino acids (AAA) pathways, and of pathways downstream from AAAs. The induction leads to production of specialized metabolites that protect the cells from oxidative damage. The regulation of the diverse AAA derived pathways is still not well understood.

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Purple Petunia × hybrida V26 plants accumulate fragrant benzenoid-phenylpropanoid molecules and anthocyanin pigments in their petals. These specialized metabolites are synthesized mainly from the aromatic amino acids phenylalanine. Here, we studied the profile of secondary metabolites of petunia plants, expressing a feedback-insensitive bacterial form of 3-deoxy-di-arabino-heptulosonate 7-phosphate synthase enzyme (AroG*) of the shikimate pathway, as a tool to stimulate the conversion of primary to secondary metabolism via the aromatic amino acids.

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In contrast to detailed knowledge regarding the biosynthesis of anthocyanins, the largest group of plant pigments, little is known about their in planta degradation. It has been suggested that anthocyanin degradation is enzymatically controlled and induced when beneficial to the plant. Here we investigated the enzymatic process in Brunfelsia calycina flowers, as they changed color from purple to white.

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Plant vacuolar peroxidases catalyze the reduction of toxic H(2)O(2) accumulated in the vacuoles by oxidizing a variety of secondary metabolites. The redundancy of peroxidases and their ability to react with a wide range of substrates have prevented the observation of a clear phenotypic effect by modifying a single gene. Here we review the correlative and partial data on vacuolar peroxidases, including evidence for genes encoding vacuolar localized peroxidases, and indications of peroxidase activity in the vacuole.

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Anthocyanins are flavonoid metabolites contributing attractive colors and antioxidant qualities to the human diet. Accordingly, there is a growing interest in developing crops enriched with these compounds. Fruits of the cultivated tomato, Solanum (S.

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Anthocyanins are the largest and best studied group of plant pigments. However, not very much is known about the fate of these phenolic pigments after they have accumulated in the cell vacuoles of plant tissues. We have previously shown that magnesium treatment of ornamentals during the synthesis of anthocyanins in the flowers or foliage caused an increase in the pigment concentration.

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