Biochemistry And Molecular Biology Of Fruit Maturation Ppt To Pdf

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Fruit ripening and softening are key traits that have an effect on food supply, fruit nutritional value and consequently, human health. Since ethylene induces ripening of climacteric fruit, it is one of the main targets to control fruit over ripening that leads to fruit softening and deterioration. The characterization of the ethylene pathway in Arabidopsis and tomato identified key genes that control fruit ripening.

Cytology, biochemistry and molecular changes during coffee fruit development.

Molecular regulation of fruit ripening

Fruit ripening is a highly coordinated developmental process that coincides with seed maturation. Key to crop improvement is a deeper understanding of the processes underlying fruit ripening. In tomato, mutations blocking the transition to ripe fruits have provided insights into the role of ethylene and its associated molecular networks involved in the control of ripening. However, the role of other plant hormones is still poorly understood.

In this review, we describe how plant hormones, transcription factors, and epigenetic changes are intimately related to provide a tight control of the ripening process. Recent findings from comparative genomics and system biology approaches are discussed. Fruits are a distinctive characteristic of Angiosperms. They occur today in a wide variety of forms and types.

The ancestral fruit, dry and dehiscent, probably emerged in the early Cretaceous period; fleshy fruits appeared later in the Cretaceous or early Tertiary Eriksson et al. The diversification of fruits from a dry dehiscent form to a fleshy drupe or berry, correlated with the rise of vertebrates, main agents of seed dispersal Knapp, The maturation of fruits is a complex and highly coordinated developmental process.

In fleshy fruits, ripening results in the production of succulent, flavorful, and soft pericarp that attract animals and facilitate seed dispersal Giovannoni, In addition to softening, fruits normally exhibit increased accumulation of sugars, acids, pigments, and volatiles that increase interest and palatability to animals.

Moreover, fruits are an important source of supplementary diet, providing minerals, vitamins, fibers, and antioxidants for humans. From an agronomical point of view, nutritional value, flavor, processing qualities, and shelf-life determine the quality of fruits. The main changes associated with ripening include color loss of green color and increase in non-photosynthetic pigments that vary depending on species and cultivar , firmness softening by cell wall degrading activities and alterations in cuticle properties , taste increase in sugar and decline in organic acids , and flavor production of volatile compounds providing the characteristic aroma.

Analytical tools that allow comprehensive phenotyping at the level of transcriptome Alba et al. Fruits are generally classified into two physiological groups, climacteric and non-climacteric, according to their respiratory activity and associated ethylene biosynthesis profiles during ripening.

Ethylene synthesis in climacteric fruits such as tomato, apple, and banana, is essential for normal fruit ripening and blocking either synthesis or perception of this hormone prevents ripening Hamilton et al. Efforts to uncover the transcriptional regulation underlying carpel and fruit development were first focused on the dry dehiscent siliques of the model plant Arabidopsis Liljegren et al. These studies clarified the role of several MADS-box transcription factors in tissue specification and mechanism of dehiscence.

However, despite the striking anatomical differences between dry and fleshy fruits, subsequent studies, primarily focused on tomato, have shown the involvement in ripening regulation of several orthologs of those MADS-box genes previously characterized in Arabidopsis Pnueli et al.

It is now clear that a part of the regulatory networks underlying fruit development have been conserved during the evolution of fleshy fruits Smaczniak et al. A number of important advances in our understanding of mechanisms that regulate ripening have also come from the characterization of monogenic tomato mutants, including ripening-inhibitor rin , non-ripening nor , colorless non-ripening Cnr , green-ripe Gr , green flesh gf , high pigment 1 hp1 , high pigment 2 hp2 , and never-ripe Nr ; Lanahan et al.

A recent study in which the transcriptome, proteome, and targeted metabolite analysis were combined during development and ripening of nor and rin mutants, has helped to refine the ethylene-regulated expression of downstream genes and added to our knowledge the role of this hormone in both protein- and metabolite regulation in tomato ripening Osorio et al. This data supported the view that nor and rin act together in a cascade to control ripening Giovannoni et al.

Recently, using a combined approach based on chromatin immunoprecipitation and transcriptome analysis, it was provided evidence that RIN interacts with the promoters of more than genes, modulating the expression of its targets by activation or repression. Fruits such as strawberry, citrus, and grape have been classified as non-climacteric, based on the lack of the respiratory burst and on the low endogenous production of ethylene compared to standard climacteric fruits Perkins-Veazie, In pepper fruits, some cultivars seem to be ethylene-insensitive, while others pepper cultivars treated with exogenous ethylene were able to stimulate the expression of ripening-specific genes Armitage, ; Ferrarese et al.

In strawberry, which has emerged as a prime model of non-climacteric fruit ripening, ethylene is relatively high in green fruits, decreases in white fruits, and finally increases again at the red stage of ripening Perkins-Veazie et al. Interestingly, this last increase is accompanied by an enhanced respiration rate that resembles the one that occurs in climacteric fruits at the onset of ripening Iannetta et al. For better understanding the function of ethylene during strawberry ripening, different approaches have been used.

Recent studies at transcriptomic and metabolomic levels in transgenic strawberry fruits with decreased ethylene sensitivity indicates that ethylene action is required for normal fruit development, acting differently in the two parts of strawberry fruit, achenes and receptacle Merchante et al. These results show that, although not as relevant as in climacteric fruits, ethylene may nevertheless play a role in strawberry fruit ripening.

Recent comparative transcriptome and metabolome studies during the maturation processes of climacteric and non-climacteric fruits tomato and pepper, respectively suggest that both species have similar ethylene-mediated signaling components. In pepper, the regulation of these genes is, however, clearly different and may reflect altered ethylene sensitivity or regulators other than ethylene than in tomato Osorio et al. Unlike the situation described in tomato the ethylene biosynthesis genes, aminocyclopropanecarboxylic acid ACC synthase, and ACC oxidase, are not induced in pepper.

However, genes downstream of ethylene perception, such as cell wall-related genes, ethylene response factor 3 ERF3 , and carotenoid biosynthesis genes, are up-regulated during pepper fruit ripening Osorio et al. Other commonly regulated genes between climacteric and non-climacteric fruits have been described. Current knowledge about the role of hormones — other than ethylene — in the development and ripening of climacteric and non-climacteric fruits is limited.

In tomato, pepper, banana, muskmelon, and strawberry, the most abundant free auxin, indoleacetic acid IAA , has been reported to decline prior to the onset of ripening; this reduction was accompanied by an increase of its conjugated form IAA-Asp; Bottcher et al. In tomato, 15 members of GH3 gene family have been described, but only for two of them is the pattern of expression associated with ripening Kumar et al. Tomato fruits overexpressing the pepper GH3 gene show anticipation of ripening Liu et al.

In non-climacteric fruits, no single growth regulator appears to play a positive role analogous to that played by ethylene, but it has been observed that auxin can negatively control the ripening of some non-climacteric fruits. In strawberry, it has been shown that the expression of many ripening-specific genes can be down-regulated by treatments with an exogenous auxin.

Also in grape auxin seems to play a negative role in the regulation of ripening with synthetic auxin treatments delaying the expression of a number of ripening-related genes Davies et al. As a consequence of the prominent role of auxin in the development and ripening of some non-climacteric fruits, little attention has been paid to possible roles of other plant hormones, such as gibberellins GAs. However, in strawberry, it has been reported that external application of GA 3 to ripening fruits caused a significant delay in the development of the red color Martinez et al.

In plants, the phytohormone abscisic acid ABA is known to be involved in various aspects of plant growth, development, and responses to environmental stresses Leung and Giraudat, ; Finkelstein and Rock, ; Himmelbach et al. In tomato, the suppression of the gene that catalyzes the first step in ABA biosynthesis NCED1 , 9-cis-epoxycarotenoid dioxygenase , results in the down-regulation of some ripening-related cell wall genes, such as polygalacturonase and pectinmethylesterase, as well as an increase in firmness and longer shelf-life Sun et al.

Similarly, reduction of NCED expression correlates with retardation of ripening in strawberry Jia et al. ABA is considered a ripening-inducer in strawberry and grape fruits Chai et al. However, we still poorly understand the developmental switch that occurs in hormone responsiveness during the transition from immature to ripe fruits.

To date, most published studies of transcriptional and metabolic regulation are of relatively low resolution at both spatial and temporal levels and are furthermore restricted in coverage of various cell molecular entities. However, new emerging technologies as well as improved statistical tools Klie et al. Additionally, the availability of high quality fruit genome sequence data Jaillon et al.

Overview of ripening regulation in climacteric fruits. The contribution of systems profiling approaches shown at the top will help identify novel regulatory genes and elucidate the interplay between epigenomic remodeling and transcriptional regulation involved during the ripening process. Epigenetic regulation of gene expression inheritance without an alteration in the primary DNA sequence is increasingly recognized as mechanism for modulating genome activity.

Naturally occurring epigenetic changes at a single gene locus in plants can result in heritable morphological variation without alteration of the underlying DNA sequence Patterson et al.

DNA methylation is one form of epigenetic regulation. It is involved in transcriptional regulation, stress responses and furthermore plays a major role in protecting the genome integrity against the activity of transposable elements TEs and other repetitive sequence Chan et al.

However, the promoter-methylated genes have a higher degree of tissue-specific expression Zhang et al. The first survey of the frequency and distribution of cytosine methylation sites in tomato dates back to more than 20 years ago, when it was found that polymorphisms in cytosine methylation between two tomato species were relatively abundant and that methylation patterns were stably inherited, from parents to offspring, segregating in a Mendelian fashion.

The presence of tissue-specific methylation patterns and the overall decrease of 5-mC frequency in developing tissues also led the authors to postulate variation of methylation status of selected alleles during plant development Messeguer et al.

More recently, the impact of cytosine methylation on tomato fruit ripening has strikingly emerged in the definition of the molecular nature of the colorless non-ripening phenotype. The tomato non-ripening Cnr mutant fails to produce ripe berries; fruits exhibit green pericarps and do not respond to external applications of ethylene. The gene at the Cnr locus was identified as a SPB protein-like using positional cloning, but the non-ripening phenotype could not be attributed to any alteration in the coding gene sequence.

Bisulfite sequencing of the Cnr mutant allele showed instead hypermethylation of cytosine in the region upstream the predicted ATG start site. This hypermethylation state correlated with a drastic reduction of Cnr gene expression Manning et al.

Therefore, the non-ripening phenotype was due to the heritable cytosine hypermethylation pattern of the region including the Cnr gene promoter. Additionally, in normal tomato fruit cv. Liberto development, the promoter of Cnr appears to be demethylated in a specific region just prior to the onset of ripening.

This lead to the hypothesis that DNA methylation contributes to the regulation of fruit ripening Seymour et al.

Recent work by Zhong et al. On the basis of the previous results on the nature of the Cnr epi mutation, the authors injected a chemical inhibitor of cytosine methylation, 5-azacytidine, directly in the locular spaces and columella of developing tomato fruits. The methylation inhibitor induced the formation of local ripe areas, red in appearance, where the expression of typical ripening-related genes phytoene synthase 1 and polygalacturonase was anticipated. Moreover, the Cnr promoter region was demethylated in red sectors with respect to green parts of the fruits, pointing at the demethylation of Cnr as the epigenetic signal sufficient to induce ripening.

The authors then extended their views on the role of cytosine methylation reporting the full tomato methylome sequences of leaves, immature and ripe fruits, including the ripening-impaired mutants Cnr and rin. The sequencing of the entire epigenome revealed at least three important results: i in wild-type fruits, the degree of methylation of regions upstream the transcription start sites TSS decreased gradually along fruit development; ii this general decline was not observed for the fruits of the ripening-impaired mutants Cnr and rin , whose CG methylation levels were constantly higher at TSS and, for Cnr , also comparable to those observed in leaves; iii the promoters of typical ripening-related genes were gradually demethylated during development of wild-type fruits.

Further evidences about the link between ripening and cytosine methylation came from the ChIP-Seq mapping of RIN binding sites during fruit development.

The set of RIN targets included genes with a known role in ripening. The analysis of methylation status of these regions showed that they were progressively demethylated during the transition from green to red ripe fruits; and this lower level of methylation correlated with higher transcript levels of RIN target genes.

A previous study showed that the binding of RIN to a limited set of promoters was inhibited in the Cnr epimutant, indicating that promoter hypermethylation may prevent RIN binding Martel et al.

These three main findings, i. The global scenario presented so far also suggests that progressive demethylation of ripening-related gene promoters may be the necessary condition for binding of transcriptional regulators, thus triggering the accumulation of ripening-related transcripts.

We anticipate that screening epigenome structure and dynamics will coexist with the analysis of conventional genetic variation in future plant breeding strategies. Epigenetic-based crop improvement approaches may radically impact fruit quality traits, especially for those traits whose allelic variation has been reduced during domestication or recent intensive breeding pressure.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

National Center for Biotechnology Information , U. Journal List Front Plant Sci v. Front Plant Sci. Published online Jun Fernie 1. Alisdair R. Author information Article notes Copyright and License information Disclaimer. Received Mar 6; Accepted May This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in other forums, provided the original authors and source are credited and subject to any copyright notices concerning any third-party graphics etc.

This article has been cited by other articles in PMC.

MOLECULAR BIOLOGY OF FRUIT MATURATION AND RIPENING

Ripening is a process in fruits that causes them to become more palatable. In general, fruit becomes sweeter , less green typically "redder" , and softer as it ripens. Even though the acidity of fruit increases as it ripens, the higher acidity level does not make the fruit seem tarter. This effect is attributed to the Brix-Acid Ratio. Early in the ripening process, fruit synthesizes compounds, including alkaloids and tannins.

Maduwanthi, R. Ripening is a genetically programmed highly coordinated irreversible phenomenon which includes many biochemical changes including tissue softening, pigment changes, aroma and flavour volatile production, reduction in astringency, and many others. Banana is one of mostly consumed fruit crops in the world. Since banana is a climactic fruit, induced ripening is essential in commercial scale banana cultivation and distribution to assure good flavour, texture, and uniform peel colour. Ethylene gas, acetylene gas liberated from calcium carbide, and ethephon are some of the commercial ripening agents used successfully in the trade and they have been widely studied for their effectiveness on initiating and accelerating the ripening process and their effect on fruit quality and health related issues. Lauryl alcohol was also shown as a ripening agent for bananas.

Fruit ripening is a highly coordinated developmental process that coincides with seed maturation. Key to crop improvement is a deeper understanding of the processes underlying fruit ripening. In tomato, mutations blocking the transition to ripe fruits have provided insights into the role of ethylene and its associated molecular networks involved in the control of ripening. However, the role of other plant hormones is still poorly understood. In this review, we describe how plant hormones, transcription factors, and epigenetic changes are intimately related to provide a tight control of the ripening process. Recent findings from comparative genomics and system biology approaches are discussed. Fruits are a distinctive characteristic of Angiosperms.


The Molecular Biology and Biochemistry of Fruit Ripening. Edited by. GRAHAM B​. SEYMOUR. MERVIN POOLE. JAMES J. GIOVANNONI. GREGORY A.


Induced Ripening Agents and Their Effect on Fruit Quality of Banana

Skip to search form Skip to main content You are currently offline. Some features of the site may not work correctly. Giovannoni Published Molecular and genetic analysis of fruit development, and especially ripening of fleshy fruits, has resulted in significant gains in knowledge over recent years. Save to Library.

The development and maturation of fruits has received considerable scientific scrutiny because of both the uniqueness of such processes to the biology of plants and the importance of fruit as a significant component of the human diet. Molecular and genetic analysis of fruit development, and especially ripening of fleshy fruits, has resulted in significant gains in knowledge over recent years. Great strides have been made in the areas of ethylene biosynthesis and response, cell wall metabolism, and environmental factors, such as light, that impact ripening. Discoveries made in Arabidopsis in terms of general mechanisms for signal transduction, in addition to specific mechanisms of carpel development, have assisted discovery in more traditional models such as tomato.

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OF FRUIT MATURATION AND RIPENING

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