Resveratrol is the most important stilbene phytoalexin synthesized naturally or induced in plants, as a part of their defense mechanism. Grapes and their derivative products, including juice and wine, are the most important natural sources of resveratrol, consisting of notably higher amounts than other natural sources like peanuts. Consumption of red wine with its presence of resveratrol explained the “French Paradox”. Hence, the demand of resveratrol from grapes is increasing. Moreover, as a natural source of resveratrol, grapes became very important in the nutraceutical industry for their benefits to human health. The accumulation of resveratrol in grape skin, juice, and wine has been found to be induced by the external stimuli: microbial infection, ultrasonication (US) treatment, light-emitting diode (LED), ultra violet (UV) irradiation, elicitors or signaling compounds, macronutrients, and fungicides. Phenylalanine ammonia lyase, cinnamate-4-hydroxylase, coumaroyl-CoA ligase, and stilbene synthase play a key role in the synthesis of resveratrol. The up-regulation of those genes have the positive relationship with the elicited accumulation of resveratrol. In this review, we encapsulate the effect of different external stimuli (biotic and abiotic stresses or signaling compounds) in order to obtain the maximum accumulation of resveratrol in grape skin, leaves, juice, wine, and cell cultures.

https://www.mdpi.com/1420-3049/22/2/294/pdf/1

An Overview of Stress-Induced Resveratrol Synthesis in Grapes: Perspectives for Resveratrol-Enriched Grape Products

Flavour is a key quality attribute of apples defined by volatile aroma compounds. Biosynthesis of aroma compounds involves metabolic pathways in which the main precursors are fatty and amino acids, and the main products are aldehydes, alcohols and esters. Some enzymes are crucial in the production of volatile compounds, such as lipoxygenase, alcohol dehydrogenase, and alcohol acyltransferase. Composition and concentration of volatiles in apples may be altered by pre- and postharvest factors that cause a decline in apple flavour. Addition of biosynthetic precursors of volatile compounds may be a strategy to promote aroma production in apples. The present manuscript compiles information regarding the biosynthesis of volatile aroma compounds, including metabolic pathways, enzymes and substrates involved, factors that may affect their production and also includes a wide number of studies focused on the addition of biosynthetic precursors in their production.

/pdf/biochemistry-of-apple-aroma-a-review-13xfp4720l.pdf

Biochemistry of Apple Aroma: A Review.

Sugars induce anthocyanin biosynthesis in plants As a conserved energy sensor, SnRK1 (SNF1-related kinase 1) is involved in sucrose-induced anthocyanin accumulation However, the exact molecular mechanism by which SnRK1 regulates the biosynthesis of anthocyanins and proanthocyanidins (PAs) in response to sucrose in plants is not clear In this study, it was found that MdSnRK11 interacted with MdJAZ18 protein which acts as a repressor in the jasmonate (JA) signaling pathway MdSnRK11 then phosphorylated MdJAZ18 to facilitate its 26S proteasome-mediated degradation, which released MdbHLH3 thereby activating the expression of the regulatory and structural genes, thus finally promoting the biosynthesis of anthocyanins and PAs Taken together, these results demonstrate the involvement of MdSnRK11 in sucrose-induced accumulation of anthocyanins and PAs For the first time, our findings shed light on the molecular mechanism by which the crosstalk of sucrose and JA signaling regulates flavonoid biosynthesis

MdSnRK1.1 interacts with MdJAZ18 to regulate sucrose-induced anthocyanin and proanthocyanidin accumulation in apple

Genome-wide identification and analysis of the MADS-box gene family in apple.

Deciphering the genetic control of flowering and ripening periods in apple is essential for breeding cultivars adapted to their growing environments. We implemented a large Genome-Wide Association Study (GWAS) at the European level using an association panel of 1,168 different apple genotypes distributed over six locations and phenotyped for these phenological traits. The panel was genotyped at a high-density of SNPs using the Axiom®Apple 480 K SNP array. We ran GWAS with a multi-locus mixed model (MLMM), which handles the putatively confounding effect of significant SNPs elsewhere on the genome. Genomic regions were further investigated to reveal candidate genes responsible for the phenotypic variation. At the whole population level, GWAS retained two SNPs as cofactors on chromosome 9 for flowering period, and six for ripening period (four on chromosome 3, one on chromosome 10 and one on chromosome 16) which, together accounted for 8.9 and 17.2% of the phenotypic variance, respectively. For both traits, SNPs in weak linkage disequilibrium were detected nearby, thus suggesting the existence of allelic heterogeneity. The geographic origins and relationships of apple cultivars accounted for large parts of the phenotypic variation. Variation in genotypic frequency of the SNPs associated with the two traits was connected to the geographic origin of the genotypes (grouped as North+East, West and South Europe), and indicated differential selection in different growing environments. Genes encoding transcription factors containing either NAC or MADS domains were identified as major candidates within the small confidence intervals computed for the associated genomic regions. A strong microsynteny between apple and peach was revealed in all the four confidence interval regions. This study shows how association genetics can unravel the genetic control of important horticultural traits in apple, as well as reduce the confidence intervals of the associated regions identified by linkage mapping approaches. Our findings can be used for the improvement of apple through marker-assisted breeding strategies that take advantage of the accumulating additive effects of the identified SNPs.

/pdf/genome-wide-association-mapping-of-flowering-and-ripening-1n86m9re3u.pdf

Genome-wide association mapping of flowering and ripening periods in apple

TIFY transcription factors comprise a plant-specific family involved in the regulation of diverse developmental processes and responses to phytohormones. However, little is known about these genes in woody species, and so, we characterized the 30-member TIFY gene family of apple (Malus × domestica Borkh.). Synteny analysis indicated that segmental, tandem, and whole genome duplications have contributed to the expansion and evolution of the family. Moreover, synteny analysis between the apple and Arabidopsis genomes demonstrated that several apple TIFY genes were found in the corresponding syntenic blocks of Arabidopsis, suggesting that the genes were established prior to the divergence of the corresponding taxonomic lineages. Additionally, phylogenetic analysis, as well as a comparison of exon–intron and protein structures, provided insights into both the evolutionary relationships and the putative functions of the family members. Tissue-specific expression analysis of specific subfamily genes revealed diverse spatiotemporal expression patterns, while expression profiles under abiotic stress and various hormone treatments indicated that the majority of the apple TIFY genes were responsive to high salinity, drought, abscisic acid, and methyl jasmonate but not salicylic acid or ethylene. This genome-wide identification and characterization of evolutionary relationships and expression profiles of apple TIFY genes will not only be useful for further analysis of this gene family and its role in stress response but may also aid in future agricultural improvement of apple stress tolerance.

Genome-wide identification and analysis of the apple (Malus × domestica Borkh.) TIFY gene family

Genome-wide identification and analysis of the aldehyde dehydrogenase (ALDH) gene superfamily in apple (Malus × domestica Borkh.)

Stilbene compounds belong to a family of secondary metabolites that are derived from the phenylpropanoid pathway. Production of the stilbene phytoalexin, resveratrol, in grape (Vitis spp.) berries is known to be induced by ultraviolet-C radiation (UV-C), which has numerous regulatory effects on plant physiology. While previous studies have described changes in gene expression caused by UV-C light in several plant species, such information has yet to be reported for grapevine. We investigated both the resveratrol content and gene expression responses of berries from V. amurensis cv. Tonghua-3 following UV-C treatment, to accelerate research into resveratrol metabolism. Comparative RNA-Seq profiling of UV-C treated and untreated grape berries resulted in the identification of a large number of differentially expressed genes. Gene ontology (GO) term classification and biochemical pathway analyses suggested that UV-C treatment caused changes in various cellular processes, as well as in both hormone and secondary metabolism. The data further indicate that UV-C induced increases in resveratrol may be related to the transcriptional regulation of genes involved in the production of secondary metabolites and signaling, as well as several transcription factors. We also observed that following UV-C treatment, 22 stilbene synthase (STS) genes exhibited increases in their expression levels and a VaSTS promoter drove the expression of the GUS reporter gene when expressed in tobacco. We therefore propose that UV-C induction of VaSTS expression is an important factor in promoting resveratrol accumulation. This transcriptome data set provides new insight into the response of grape berries to UV-C treatment, and suggests candidate genes, or promoter activity of related genes, that could be used in future functional and molecular biological studies of resveratrol metabolism.

/pdf/insights-into-the-mechanisms-underlying-ultraviolet-c-4cs6wxtfbt.pdf

Chonghui Fan

Papers

Genome-wide identification and analysis of the apple (Malus × domestica Borkh.) TIFY gene family

Genome-wide identification and analysis of the aldehyde dehydrogenase (ALDH) gene superfamily in apple (Malus × domestica Borkh.)

Insights into the Mechanisms Underlying Ultraviolet-C Induced Resveratrol Metabolism in Grapevine (V. amurensis Rupr.) cv. “Tonghua-3”