Recent advances on polysaccharides, lipids and protein based edible films and coatings: A review.

A method of identifying microorganisms with reduced adaptability to a particular environment, wherein (1) each microorganism is independent by insertional inactivation of a gene with a nucleic acid comprising a unique marker sequence. Mutating to provide a plurality of microorganisms, or clones of said microorganisms, such that each mutation has a different label sequence; (2) providing storage samples of each mutation produced by step (1), respectively, and providing storage nucleic acids each comprising a unique label sequence from each mutation; (3) introducing a plurality of mutations produced by step (1) into the specific environment such that the microorganisms capable of growing in the specific environment grow in the above environment; (4) recovering the microorganisms or selected portions thereof from the environment and separating nucleic acids from the recovered microorganisms; (5) comparing all label sequences in the nucleic acid isolated in step (4) with the unique label sequences of each of the stored mutations as in step (2); and (6) any label isolated in step (4). Screening for individual mutations that also do not have a sequence.

Identification of genes

One of the major growth segments in the food retail industry is fresh and minimally processed fruits and vegetables. This new market trend has thus increased the demands to the food industry for seeking new strategies to increase storability and shelf life and to enhance microbial safety of fresh produce. The technology of edible coatings has been considered as one of the potential approaches for meeting this demand. Edible coatings from renewable sources, including lipids, polysaccharides, and proteins, can function as barriers to water vapor, gases, and other solutes and also as carriers of many functional ingredients, such as antimicrobial and antioxidant agents, thus enhancing quality and extending shelf life of fresh and minimally processed fruits and vegetables. This review discusses the rationale of using edible coatings on fresh and minimally processed produce, the challenges in developing effective coatings that meet the specific criteria of fruits and vegetables, the recent advances in the development of coating technology, the analytical techniques for measuring some important coating functionalities, and future research needs for supporting a broad range of commercial applications.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1541-4337.2007.00018.x

Innovations in the Development and Application of Edible Coatings for Fresh and Minimally Processed Fruits and Vegetables

Background

The control of plant anthocyanin accumulation is via transcriptional regulation of the genes encoding the biosynthetic enzymes. A key activator appears to be an R2R3 MYB transcription factor. In apple fruit, skin anthocyanin levels are controlled by a gene called MYBA or MYB1, while the gene determining fruit flesh and foliage anthocyanin has been termed MYB10. In order to further understand tissue-specific anthocyanin regulation we have isolated orthologous MYB genes from all the commercially important rosaceous species.

Results

We use gene specific primers to show that the three MYB activators of apple anthocyanin (MYB10/MYB1/MYBA) are likely alleles of each other. MYB transcription factors, with high sequence identity to the apple gene were isolated from across the rosaceous family (e.g. apples, pears, plums, cherries, peaches, raspberries, rose, strawberry). Key identifying amino acid residues were found in both the DNA-binding and C-terminal domains of these MYBs. The expression of these MYB10 genes correlates with fruit and flower anthocyanin levels. Their function was tested in tobacco and strawberry. In tobacco, these MYBs were shown to induce the anthocyanin pathway when co-expressed with bHLHs, while over-expression of strawberry and apple genes in the crop of origin elevates anthocyanins.

Conclusions

This family-wide study of rosaceous R2R3 MYBs provides insight into the evolution of this plant trait. It has implications for the development of new coloured fruit and flowers, as well as aiding the understanding of temporal-spatial colour change.

An R2R3 MYB transcription factor associated with regulation of the anthocyanin biosynthetic pathway in Rosaceae

In mammals, cadmium is widely considered as a non-genotoxic carcinogen acting through a methylation-dependent epigenetic mechanism. Here, the effects of Cd treatment on the DNA methylation patten are examined together with its effect on chromatin reconfiguration in Posidonia oceanica. DNA methylation level and pattern were analysed in actively growing organs, under short- (6 h) and long- (2 d or 4 d) term and low (10 mM) and high (50 mM) doses of Cd, through a Methylation-Sensitive Amplification Polymorphism technique and an immunocytological approach, respectively. The expression of one member of the CHROMOMETHYLASE (CMT) family, a DNA methyltransferase, was also assessed by qRT-PCR. Nuclear chromatin ultrastructure was investigated by transmission electron microscopy. Cd treatment induced a DNA hypermethylation, as well as an up-regulation of CMT, indicating that de novo methylation did indeed occur. Moreover, a high dose of Cd led to a progressive heterochromatinization of interphase nuclei and apoptotic figures were also observed after long-term treatment. The data demonstrate that Cd perturbs the DNA methylation status through the involvement of a specific methyltransferase. Such changes are linked to nuclear chromatin reconfiguration likely to establish a new balance of expressed/repressed chromatin. Overall, the data show an epigenetic basis to the mechanism underlying Cd toxicity in plants.

/pdf/in-posidonia-oceanica-cadmium-induces-changes-in-dna-3cu7uj83mr.pdf

In Posidonia oceanica cadmium induces changes in DNA methylation and chromatin patterning

Postharvest sweet cherry quality and safety maintenance by Aloe vera treatment: A new edible coating

Chilling and heat requirements of sweet cherry cultivars and the relationship between altitude and the probability of satisfying the chill requirements

An improved method for adventitious regeneration from apricot leaves is described. The use of the ethylene inhibitors silver thiosulphate (30-60 micro M) or aminoethoxyvinylglycine (0.5 micro M) increased regeneration percentages in Helena and Canino apricot cultivars and also the consistency of results from different experiments. Use of "Pure Agar" also improved regeneration from Helena leaves as compared with agargel or agarose. Regeneration rates for Canino were dependent on the medium in which the shoots were micropropagated. When different antibiotics were tested for their influence on regeneration, the combination of cefotaxime (0.13 m M) plus vancomycin (0.63 m M), which efficiently controls Agrobacterium growth, also increased regeneration percentages in Helena two-fold but did not affect regeneration in Canino. Kanamycin, an antibiotic widely used for selection of nptII transformed cells, promoted more rapid regeneration and higher regeneration rates from Helena leaves when added at low concentrations (8.6 and 17.1 micro M). With this improved procedure, regeneration from apricot leaves has been increased more than 200% as compared with rates reported previously.

Ethylene inhibitors and low kanamycin concentrations improve adventitious regeneration from apricot leaves.

The effect of extracts of the brown algae Cystoseira myriophylloides, Laminaria digitata, and Fucus spiralis against the tomato pathogens Verticillium dahliae and Agrobacterium tumefaciens was evaluated in vitro and in the greenhouse. A significant inhibition of growth was observed only with methanolic seaweed extracts (MSE). Disease resistance was assessed in the greenhouse against Verticillium wilt using spray application of aqueous seaweed extracts (ASE) on the whole plant or using seed imbibition. Both methods significantly reduced disease severity whatever the algal species, though protection observed after seed treatments was higher than that observed after spray treatment. Spray application of ASE from C. myriophylloides and F. spiralis also resulted in significant reduction of Crown gall disease caused by the bacterial pathogen A. tumefaciens. ASE-treated plants had significantly higher levels of activity of defense enzymes polyphenol oxidase and peroxidase compared to the control. ASE did not inhibit mycelium growth of V. dahliae or development of A. tumefaciens in vitro; it is therefore suggested that induced resistance is probably the main mechanism of protection afforded by ASE.

Protective effect of three brown seaweed extracts against fungal and bacterial diseases of tomato

A protocol for Agrobacterium-mediated stable transformation for scored, whole leaf explants of the apricot (Prunus armeniaca) cultivar Helena was developed. Regenerated shoots were selected using a two-step increased concentrations of paromomycin sulphate. Different factors affecting survival of transformed buds, including possible toxicity of green fluorescent protein (GFP) and time of exposure to high cytokine concentration in the regeneration medium, were examined. Transformation efficiency, based on PCR analysis of individual putative transformed shoots from independent lines was 5.6%, when optimal conditions for bud survival were provided. Southern blot analysis on four randomly chosen PCR-positive shoots confirmed the presence of the nptII transgene. This is the first time that stable transformation of an apricot cultivar is reported and constitutes also one of the few reports on the transformation of Prunus cultivars.

Nuria Alburquerque

Papers

Postharvest sweet cherry quality and safety maintenance by Aloe vera treatment: A new edible coating

Chilling and heat requirements of sweet cherry cultivars and the relationship between altitude and the probability of satisfying the chill requirements

Ethylene inhibitors and low kanamycin concentrations improve adventitious regeneration from apricot leaves.

Protective effect of three brown seaweed extracts against fungal and bacterial diseases of tomato

Agrobacterium-mediated transformation of apricot (Prunus armeniaca L.) leaf explants.