The last decade has been characterized by a decrease in peach (Prunus persica) fruit consumption in many countries, foremost due to unsatisfactory quality. The sugar content is one of the most important quality traits perceived by consumers, and the development of novel peach cultivars with sugar-enhanced content is a primary objective of breeding programs to revert the market inertia. Nevertheless, the progress reachable through classical phenotypic selection is limited by the narrow genetic bases of peach breeding material and by the complex quantitative nature of the trait, which is deeply affected by environmental conditions and agronomical management. The development of molecular markers applicable in MAS or MAB has become an essential strategy to boost the selection efficiency. Despite the enormous advances in ‘omics’ sciences, providing powerful tools for plant genotyping, the identification of the genetic bases of sugar-related traits is hindered by the lack of adequate phenotyping methods that are able to address strong within-plant variability. This review provides an overview of the current knowledge of the metabolic pathways and physiological mechanisms regulating sugar accumulation in peach fruit, the main advances in phenotyping approaches and genetic background, and finally addressing new research priorities and prospective for breeders.

Clusters of Aleatico winegrape were picked at 18 degrees Brix and placed at 10, 20, or 30 degrees C, 45% relative humidity (RH) and 1.5 m/s of air flow to dehydrate the berries up to 40% of loss of initial fresh weight. Sampling was done at 0, 10, 20, 30, and 40% weight loss (wl). Selected polyphenols and sugar content (expressed as SSC = soluble solids content) both measured on dry weight basis, polyphenol oxidase (PPO), and phenylpropanoid pathway gene expression were analyzed. Phenolic acids increased significantly at 20% wl at 20 degrees C, while at 10 degrees C the increase was lower. Stilbenes (trans-resveratrol and trans-piceid) and catechins rose more than double to 100 mg/kg and more than 3-fold to 135 mg/kg at 20 degrees C and 10% wl. At 10 degrees C the increase of these compounds was less, but higher than initial values. At 30 degrees C, except for a significant rise at 10% wl for catechins and stilbenes, all the rest of the compounds diminished. Anthocyanins increased at 10 and 20 degrees C, but decreased at 30 degrees C. PPO rapidly increased at 20 and 30 degrees C at 10% wl and then declined, while at 10 degrees C the activity lasted longer. Relative gene expression of phenylalanine ammonia lyase (PAL), stilbene synthase (STS), chalcone isomerase (CHI), dihydroflavonol reductase (DFR) were upregulated at 10 degrees C more than at 20 degrees C, at 20% wl, while at 30 degrees C the gene expression was downregulated.

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Moringa oleifera is a widespread plant with substantial nutritional and medicinal value. We postulated that microRNAs (miRNAs), which are endogenous, noncoding small RNAs regulating gene expression at the post-transcriptional level, might contribute to the medicinal properties of plants of this species after ingestion into human body, regulating human gene expression. However, the knowledge is scarce about miRNA in Moringa. Furthermore, in order to test the hypothesis on the pharmacological potential properties of miRNA, we conducted a high-throughput sequencing analysis using the Illumina platform. A total of 31,290,964 raw reads were produced from a library of small RNA isolated from M. oleifera seeds. We identified 94 conserved and two novel miRNAs that were validated by qRT-PCR assays. Results from qRT-PCR trials conducted on the expression of 20 Moringa miRNA showed that are conserved across multiple plant species as determined by their detection in tissue of other common crop plants. In silico analyses predicted target genes for the conserved miRNA that in turn allowed to relate the miRNAs to the regulation of physiological processes. Some of the predicted plant miRNAs have functional homology to their mammalian counterparts and regulated human genes when they were transfected into cell lines. To our knowledge, this is the first report of discovering M. oleifera miRNAs based on high-throughput sequencing and bioinformatics analysis and we provided new insight into a potential cross-species control of human gene expression. The widespread cultivation and consumption of M. oleifera, for nutritional and medicinal purposes, brings humans into close contact with products and extracts of this plant species. The potential for miRNA transfer should be evaluated as one possible mechanism of action to account for beneficial properties of this valuable species.

Functional foods include compounds with nutritional and health properties. The human diet could play a stronger role in cancer prevention. Only a few studies have described the presence of plant small RNA, in humans who were fed with plant foods, which demonstrated the ability of these molecules to modulate consumer’s genes and evidenced the existence of a plant-animal regulation. Through in silico prediction, Olea europaea small RNAs (sRs), which had been previously reported as miRNAs, were identified, each with functional homology to hsa-miR34a. According to this initial funding, we investigated the ability of oeu-sRs to regulate tumorigenesis in human cells. The transfection of these synthetic oeu-sRs reduced the protein expression of hsa-miR34a mRNA targets, increased apoptosis and decreased proliferation in different tumor cells; by contrast, no effect was observed in PBMCs from healthy donors. The introduction of oeu-small RNA in hsa-miR34a-deficient tumor cells restores its function, whereas cells with normal expression of endogenous hsa-miR34a remained unaffected. The natural oeu-small RNAs that were extracted from O. europaea drupes induce the same effects as synthetic sRs. Careful research on the small RNA sequences executed for mapping and annotation in the genome of O. europaea var. Sylvestris and var. Farga led to the hypothesis that RNA fragments with functional homology to human miRNAs could be generated from the degradation of regions of RNA transcripts. These results indicate the possibility of developing novel natural non-toxic drugs that contain active plant-derived tumor-suppressing small RNA with functional homology to hsa-miRNAs and that can support antineoplastic strategies.