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Methylation affects different aspects of genetic material stability, gene expression regulation, and histone modification. The previous reports depicted that DNA and histone methylation regulates plant growth and development. In this study, we evaluated the effects of DNA and histone methylation on ‘Hongjia’ strawberry and ‘Lichun’ tomato. We investigated the transient transformation system for arginine methyltransferase (FvPRMT1.5) overexpression and interference and assessed the phenotypic appearance and mRNA and protein expression levels. Results depicted that changes in methylation levels caused inhibition of carotenoids and anthocyanins. Furthermore, the profiling of aroma components was altered in response to 5-azacytidine. DNA hypomethylation induced the expression levels of genes involved in photosynthesis, flavonoid biosynthesis, and hormone signal transduction pathways, while the expression levels of related proteins showed a downward trend. Overall, we proposed a model that reveals the possible regulatory effects of DNA and histone methylation during fruit ripening.

Flavonoids in grapes contribute the quality of the berry, but the flavonoid diversity and the regulatory networks underlying the variation require a further investigation. In this study, we integrated multi-omics data to systematically explore the global metabolic and transcriptional profiles in the skins and pulps of three grape cultivars. The results revealed large-scale differences involved in the flavonoid metabolic pathway. A total of 133 flavonoids, including flavone and flavone C-glycosides, were identified. Beyond the visible differences of anthocyanins, there was large variation in other sub-branched flavonoids, most of which were positively correlated with anthocyanins in grapes. The expressions of most flavonoid biosynthetic genes and the major regulators MYBA1were strongly consistent with the changes in flavonoids. Integrative analysis identified two novel transcription factors (MYB24and MADS5) and two ubiquitin proteins (RHA2) as promising regulatory candidates for flavonoid biosynthesis in grapes. Further verification in various grape accessions indicated that five major genes including flavonol 3′5′-hydroxylase(F3′5′H), UDP-glucose:flavonoid 3-O-glycosyl-transferase, anthocyanin O-methyltransferase, acyltransferase(3AT), and glutathione S-transferase(GST4) controlled flavonoid variation in grape berries. These findings provide valuable information for understanding the mechanism of flavonoid biosynthesis in grape berries and the further development of grape health products.

The distal end of grape berries preferentially cracks during the soaking process in vitro, which may be related to preferential water uptake and cell anatomy. Thus, the relationship between water uptake and cell anatomical structure was assessed using 49 grape varieties. In vitro immersion experiments were performed on mature berries to measure the differences in berry-cracking properties. A whole-berry in vitro staining method was used to trace the water uptake of the vascular bundles, and paraffin sections were used to observe and analyze the structural parameters of the different tissues. The results showed that the berry-cracking rate and water uptake of the distal end of berries prone to cracking were significantly higher than that of the resistant berries. Compared with the berries that were resistant to cracking, the berries that were prone to cracking possessed a thin cuticle, epidermis and sub-epidermis. Dye accumulated in the distal end of the cracking-prone berries, which even exhibited cracking during the dyeing process. However, less dye accumulated on the surface of the cracking-resistant varieties and was only sporadically distributed on the surface. In addition, cracking of the distal end of the berry may also be related to other shape and size parameters of the cells in cell layer. Analysis of vascular bundle water transport and the differences in the cell structure characteristics of the different varieties, offered a preliminary explanation for why the distal end of the berry is prone to cracking, providing theoretical support for further research on the mechanisms of berry cracking.

Brassinosteroids (BRs) are known to regulate plant growth and development. However, only little is known about their mechanism in the regulation of berry development in grapes. This study demonstrates that BR treatment enhances the accumulation of fruit sugar components, reduces the content of organic acids (e.g., tartaric acid), promotes coloration, and increases the anthocyanin content in grape berries at the onset of the veraison, half veraison, and full veraison stages at the rate of 0.0998, 0.0560, and 0.0281 mg·g–1,respectively. In addition, BR treatment was also found to accelerate the biosynthesis of terpenoid aroma components, such as α-pinene, d-limonene, and γ-terpinene, which influence the aromatic composition of grapes. BRs can negatively regulate the expression of VvHMGR, a key gene involved in the mevalonate (MVA) pathway, and reduce the activity of 3-hydroxy-3-methylglutaryl CoA reductase (HMGR). Inhibiting the expression of HMGRpromoted the accumulation of anthocyanins and fruit coloration. Meanwhile, after the inhibition, the contents of auxin indole-3-acetic acid (IAA), abscisic acid (ABA), and brassinosteroid (BR) increased, while gibberellin (GA3) and zeatin riboside (ZR) decreased, and its aromatic composition also changed. Therefore, it may be concluded that BRs inhibited HMGR activity and cooperated with VvHMGRto regulate the formation of color, aroma, and other quality characteristics in fruits.

Grapevine is extensively grown for fresh table grapes, wine, and other processed products worldwide. DNA methylation levels are regulated by DNA methylation maintenance and DNA methylation removal involved in the grapevine growth. We comprehensively analyzed the transcriptome and metabolome of the ‘Kyoho’ fruit with or without demethylation and screened for a large number of differential genes and metabolites. Color, hardness, and aroma are the most obvious traits reflecting the ripening of grapes. We used gas chromatography–mass spectrometry and high-performance liquid chromatography to understand the changes in metabolites during ripening. We cloned many key genes selected by transcriptome analysis and found that intron retention was observed in VvCHS, VvDFR, and VvGST. The imbalance of methylation levels affects the alternative splicing of pre-mRNA, which makes the translation process abnormal and affects gene expression. In addition, analyzing promoters of some genes, such as proVvGST4and proVvUFGT, found that the promoters of these genes after demethylating were more difficult to methylate. Taken together, this study will provide new insights into comprehension of the molecular mechanism of methylation during ripening of grape berries. In addition, the study provides some genetic information to help guide our improvement, cultivation, and management of grapes in the future.

The coloring process of grape flesh is valuable for research and promotion of the high nutritional quality of anthocyanins. ‘Summer Black’ and it is new red flesh mutant were used to analyze the changes of anthocyanin biosynthesis during grape berry development. Eighteen kinds of anthocyanins were detected in mature berries of the two cultivars, but the content of most 3′- and 3′,5′-substituted anthocyanins was higher in the skin of the mutant. Anthocyanin accumulation occurred simultaneously in the skin and flesh of the mutant, and their types and content were more abundant in the former. For the mutant, there were only CHS, OMT, MYBA3, and MYBPA1at lower transcriptional level in the flesh during veraisonwhen compared with these in the skin, which might be an important factor to limit the anthocyanin accumulation in the flesh. The occurrence of red flesh might be related the enhancement of anthocyanin biosynthesis in the whole berry.

With the development of molecular biology, some DNA-based technologies have showed great potentiality in promoting the efficiency of crop breeding program, protecting germplasm resources, improving the quality and outputs of agricultural products, and protecting the ecoenvironment etc., making their roles in modern agriculture more and more important. To better understand the application of DNA technologies in agriculture, and achieve the goals to promote their utilities in modern agriculture, this paper describes, in some different way, the applications of molecular markers, transgenic engineering and gene's information in agriculture. Some corresponding anticipations for their development prospects are also made.

AbstractDNA fingerprinting is both a popular and important technique with great advantages in plant cultivar identification. Despite this fact, this technique has never been used widely and efficiently in practical plant identification since analysis and recording of data generated from fingerprinting and genotyping for future reference is tedious and difficult. We report a novel strategy developed for efficient recording of DNA molecular fingerprints of genotyped plant individuals, which could be readily used as efficient reference information for quick plant identification. 25 orange- or white-fl eshed loquat cultivars that are commercially important in China, were identified using this strategy which employed random amplified polymorphic DNA (RAPD) marker. Utilization of the strategy was verified by identification of three randomly chosen groups of loquat culti-vars among the 25. The advantages of this approach include use of fewer primers and separation of all cultivars by the corresponding primers marked on the diagram. Importantly, the diagram could be easily referred to in identification of loquat cultivars in commerial practice.

Production of seedless mandarins such as ‘Nules’ clementine mandarin (Citrus clementina Hart. Ex Tan.) and ‘Afourer’ mandarin [C. sinensis (L.) Osbeek x C. reticulata Blanco] is increasing in California as consumers' interest in seedless, easy peeling, and good tasting mandarins increases. The fruit would produce seeds if cross-pollination with compatible pollen source occurred. It is almost impossible to prevent cross-pollination between compatible mandarin cultivars by honeybees (Apis mellifera L.) within the multi-faceted agricultural environment in California. To produce seedless mandarin, growers either plant a single cultivar in a large solid block or try to use pollen-sterile navel oranges (C. sinensis) or satsuma mandarins (C. unshiu Marco.) as buffers to prevent cross-pollination. The question of how many rows of buffer trees or spacing can effectively prevent cross-pollination by honeybees between compatible mandarins is unclear. We initiated a study using fluorescent-labeled AFLP markers to determine the pollen parentages of ‘Nules’ clementine seedlings and ‘Afourer’ mandarin seedlings from two orchards in California. The longest distance of pollen flow at an orchard near Madera was 521 m. The pollen of ‘Minneala’ tangelo (C. reticulata x C. paradisi Macf.) was able to disperse across a minimum of 92 rows of ‘Lane Late’ navel oranges plus two rows of ‘Afourer’ mandarins to pollinate ‘Afourer’ mandarins. We also found that all the seedlings of ‘Nules’ clementine mandarin at an orchard near Bakersfield had been poninated by ‘Afourer’ mandarin pollen. The pollen of ‘Afourer’ mandarin was able to disperse up to distances between 837 and 960 m to pollinate ‘Nules’ clementine. The pollen dispersal distance found in this study was at least 16 times longer than previously reported in a citrus orchard. Growers need to consider a much larger space or buffer rows to prevent cross-pollination and produce seedless mandarins in California. [ABSTRACT FROM AUTHOR]

Bud dormancy is one of the most important defensive mechanisms through which plants resist cold stress during harsh winter weather. DAM, Dof, and WRKYhave been reported to be involved in many biological processes, including bud dormancy. In the present study, grapevine (Vitis vinifera) and other thirteen plants (six woody plants and seven herbaceous plants) were analyzed for the quantity, sequence structure, and evolution patterns of their DAM, Dof, and WRKYgene family members. Moreover, the expression of VvDAM, VvDof, and VvWRKYgenes was also investigated. Thus, 51 DAM, 1,205 WRKY, and 489 Dofgenes were isolated from selected genomes, while 5 DAM, 114 WRKY, and 50 Dofduplicate gene pairs were identified in 10 genomes. Moreover, WGD and segmental duplication events were associated with the majority of the expansions of Dofand WRKYgene families. The VvDAM, VvDof, and VvWRKYgenes significantly differentially expressed throughout bud dormancy outnumbered those significantly differentially expressed throughout fruit development or under abiotic stresses. Interestingly, multiple stress responsive genes were identified, such as VvDAM(VIT_00s0313g00070), two VvDofgenes (VIT_18s0001g11310 and VIT_02s0025g02250), and two VvWRKYgenes (VIT_07s0031g01710 and VIT_11s0052g00450). These data provide candidate genes for molecular biology research investigating bud dormancy and responses to abiotic stresses (namely salt, drought, copper, and waterlogging).

Grapes are categorized as a non-climacteric type of fruit which its ripening is not associated to important rises in respiration and ethylene synthesis. The starch metabolism shares a certain role in the carbohydrate metabolic pathways during grape berry development, and is regarded as an important transient pool in the pathway of sugar accumulation. However, the comprehensive role of starch and its contribution to the quality and flavor of grape berry have not been explored thoroughly. In this study, the expression levels of genes enzyme activities and carbohydrate concentrations related to starch metabolism, were analyzed to understand the molecular mechanism of starch accumulation during grape berry development. The results indicated that starch granules in grape berry were located at the chloroplast in the sub-epidermal tissues, acting as the temporary reserves of photosynthetic products to meet the needs for berry development, and relatively high starch contents could be detected at véraison stage. Moreover, both ADP-glucose pyrophosphorylase (EC 2.7.7.27) and sucrose phosphate synthase (EC 2.3.1.14) involved in starch synthesis displayed elevated gene expression and enzymes activities in the sub-epidermal tissue, while α- and β-amylases involved in its degradation were highly transcribed and active in the central flesh, explaining the absence of starch in this last tissue. Change in the gene expression and activities of ADP-glucose pyrophosphorylase, β-amylase and sucrose phosphate synthase revealed that they were regulated by the circadian rhythms in the fruitlets compared with those in the leaves. Both the morphological, enzymological and transcriptional data in this study provide advanced understandings on the function of starch during berry development and ripening that are so important for berry quality. This study will further facilitate our understanding of the sugar metabolism in grape berry as well as in other plant species.