1,720,986 research outputs found
Molecular and biochemical aspects underlying polyamine modulation of fruit development and ripening
No full textPurpose of review: Improved knowledge of the physiology of polyamines (PAs) during fruit development and ripening can be
achieved not only by analysing endogenous PA levels and biosynthesis, but also through experimental protocols aimed at manipulating fruit PA levels. These include: exogenous PA supply under field and postharvest conditions, isolation of mutants, and, when possible, genetic engineering of PA biosynthetic genes. This article reviews the main molecular and biochemical results obtained in this field in relation to fruit development and ripening and functional properties. Findings: PA biosynthesis is developmentally regulated, and gene expression is sensitive to exogenous and endogenous stimuli including PAs themselves. Manipulating PA titres leads to developmental changes, and almost invariably to ripening delay and prolong shelflife. This is associated with inhibition of ethylene-related gene expression, retention of flesh firmness, inhibition of activities of cell wall degrading enzymes, and, in some cases, improved nutritional and antioxidant attributes of the fruit. The only transcriptome and metabolome profiling analyses available confirm that fruits engineered for high PA content exhibit a high metabolic status compatible with a high nutritional quality. Directions for future research: This survey shows that the molecular and biochemical bases of PA function are in their infancy. Thus, further transcriptomic and metabolic profiling of PA-treated or PA over-accumulating fruits is required to shed light on this very promising scenario. For practical purposes, besides optimising application strategies, commercial products containing PAs would be highly desirable
Genes involved in the control of ethylene biosynthesis during climacteric of prunus persica fruit.
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Sunred®, a botanical extract-based biostimulant, enhances polyphenols accumulation and improves quality of musts
No full textSUNRED® is a biostimulant produced by Biolchim SpA containing phenylalanine, methionine, monosaccharides, and botanical extracts rich in oxylipins: naturally occurring compounds involved in several ripening-related processes. SUNRED® has been shown to improve fruit color, ripening uniformity, and soluble sugar content in apple, cherry, grape, melon, and tomato. In the present study, SUNRED® application in grape (‘Cabernet Sauvignon’ and ‘Prosecco’) was shown to increase accumulation of antocyanins, polyphenols and sugar content in musts without altering acidity and other quality parameter
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Effetti di zinco e rame sull'espressione delle metallotioneine e sul contenuto di poliammine in Populus alba L. in micropropagazione.
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A new index based on vis spectroscopy to characterize the progression of ripening in peach fruit
No full textIn peach fruit (Prunits persica L. Batsch), establishing the optimal harvest time is a crucial issue, since fruit shelf-life potential and quality are closely related to the ripening stage at harvest. In order to develop a non-destructive index for monitoring the progression of ripening, the difference in absorbance between two wavelengths near the chlorophyll-a absorption peak (670 and 720 nm; index of absorbance difference, I-AD) was related to the time course of ethylene production during on-tree ripening of peaches (cv. 'Fayette') and nectarines (cvs. 'Laura' and 'Stark Red Gold'). For each variety, consecutive stages of ripening, as defined according to ethylene production (pre-climacteric, climacteric, post-climacteric), occurred in the same ranges Of I-AD in different years (2003 and 2004). In 2005, the relationship I-AD/ethylene production was used to classify fruit at harvest according to their ripening stage (class 0: pre-climacteric; class 1: onset of climacteric; class 2: climacteric). For each cultivar, the transition from class I to 2 was marked by increased ethylene production, and reduced flesh firmness (FF) and fitratable acidity (TA). In contrast, fruit quality traits did not discriminate between fruit belonging to classes 0 and 1. In 'Stark Red Gold' nectarines, the robustness of the I-AD was further corroborated by changes in transcript levels of genes which are either up- or down-regulated during peach fruit ripening. Class 0 fruit had the lowest transcript amount of the up-regulated genes and the highest of the down-regulated ones, while the opposite occurred in class 2 fruit. Moreover, mRNA abundance of some marker genes discriminated class 0 and 1 fruit. Peaches and nectarines graded at harvest according to the I-AD also differed in their postharvest ripening behaviour: fruit with higher I-AD produced lower amounts of ethylene, began to soften later, and maintained higher TA than those with lower I-AD. Present data demonstrate that the I-AD identifies physiological changes occurring during ripening regardless of the fact that they might have or not led to appreciable modifications in fruit quality. Therefore, the I-AD can be regarded as a very promising tool both for practical and scientific applications, since it allows to monitor on-tree fruit ripening, to establish accurately the optimal harvest time, and to reduce the variability which is present in fruit batches. (C) 2008 Elsevier B.V. All rights reserved
I GIASMONATI NEL CONTROLLO DELLA MATURAZIONE DELLE NETTARINE STARK RED GOLD: RELAZIONI CON ETILENE E POLIAMMINE
No full textI giasmonati (JA) costituiscono un segnale importante nell’elicitazione di risposte a stress mediante induzione di JA-induced proteins (JIPs); tra queste, gli enzimi biosintetici delle poliammine. E’ stato riportato un ruolo attivo dei JA anche nei processi di sviluppo, quali la crescita e la maturazione dei frutti, e in post-raccolta. In polpa di mela e ciliegia i livelli di JA mostrano un picco di concentrazione durante le fasi precoci di crescita (divisione cellulare); in mela tali livelli salgono nuovamente all’inizio del climaterio etilenico.
Dati esogenamente questi composti inducono una serie di risposte biologiche: stimolano la produzione di beta-carotene in pomodoro, riducono il danno da freddo in post-raccolta in mango, riducono la muffa verde in pompelmo e promuovono lo sverdimento in mela. Tuttavia, le relazioni reciproche tra JA ed etilene non sono ben stabilite. In mela il metilgiasmonato (MJ) stimola la produzione di etilene in frutti pre-climaterici e la inibisce in quelli post-climaterici. Alcuni Autori suggeriscono che l’effetto del MJ sullo sverdimento della mela sia almeno in parte indipendente dall’etilene. Risultati contraddittori sono stati ottenuti anche in altri sistemi modello.
Una relazione ben stabilita è quella tra JA e poliammine. I JA infatti stimolano fortemente il metabolismo delle poliammine con forti riflessi sui loro coniugati fenolici. I livelli di poliammine, che sono importanti regolatori della crescita, variano durante lo sviluppo del frutto e il trattamento del frutto in maturazione con poliammine libere riduce l’emissione di etilene e il rammollimento della polpa.
Questo lavoro riporta i risultati di un’indagine atta a stabilire quali siano le relazioni reciproche tra JA ed etilene allo scopo di chiarire i meccanismi fisiologici coinvolti nel controllo della maturazione e della post-raccolta nelle nettarine. A seguito della somministrazione esogena di JA in campo (MJ e propilgiasmonato, PJ) al frutto in S3, l’emissione di etilene al climaterio, così come l’evoluzione dei principali parametri di qualità del frutto, viene inibita da PJ ma non da MJ. L’espressione di ACO1 è influenzata solo da MJ. I livelli di poliammine libere sono significativamente incrementati sia nell’esocarpo che nel mesocarpo da entrambi i trattamenti. L’espressione dell’enzima che decarbossila l’S-adenosilmetionina (SAM), precursore comune dell’etilene e delle poliammine, non è influenzata dai trattamenti.
L’inibizione dell’emissione di etilene e il rallentamento della maturazione che ne consegue sono associati ad incrementi nel contenuto di poliammine che potrebbero contribuire all’effetto antisenescente dei trattamenti. Si conferma così il ruolo dei JA nel controllo della maturazione del frutto e il coinvolgimento delle poliammine in tale processo
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