Two G-quadruplex ligands [Pt(L(a))(DMSO)Cl] (Pt1) and [Pt(L(b))(DMSO)Cl] (Pt2) have been synthesized and fully characterized. The two complexes are more selective for SK-OV-3/DDP tumor cells versus normal cells (HL-7702). It was found that both Pt1 and Pt2 could be a telomerase inhibitor targeting G-quadruplex DNA. This is the first report demonstrating that telomeric, c-myc, and bcl-2 G-quadruplexes and caspase-3/9 preferred to bind with Pt2 rather than Pt1, which also can induce senescence and apoptosis. The different biological behavior of Pt1 and Pt2 may correlate with the presence of a 6-hydroxyl group in L(b). Importantly, Pt1 and Pt2 exhibited higher safety in vivo and more effective inhibitory effects on tumor growth in the HCT-8 and NCI-H460 xenograft mouse model, compared with cisplatin. Taken together, these mechanistic insights indicate that both Pt1 and Pt2 display low toxicity and could be novel anticancer drug candidates.

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Deciphering the genetic control of grape berry traits is crucial for optimizing yield, fruit quality, and consumer acceptability. In this study, an association panel of 179 grape genotypes comprising a mixture of ancient cultivars, landraces, and modern varieties collected worldwide were genotyped with genotyping-by-sequencing using a genome-wide association approach based on 32,311 single-nucleotide polymorphism (SNP) markers. Genome-wide efficient mixed-model association was selected as the optimal statistical model based on the results of known control loci of grape berry color traits. Many of the associated SNPs identified in this study were in accordance with the previous QTL analyses using biparental mapping. The grape skin color locus was found to be associated with a mybA transcription factor on chromosome 2. Two strong and distinct association signals associated with berry development periods were found on chromosome 16. Most candidate genes of the interval were highlighted as receptor-like protein kinase. For berry weight, significant association loci were identified on chromosome 18, as previously known, and on chromosome 19 and chromosome 17, as newly mapped. Berry flesh texture was newly located on chromosome 16; candidate genes in the interval were related to calcium. Berry flavor was determined on chromosome 5. Genomic regions were further investigated to reveal candidate genes. In this work, we identified interesting genetic determinants of grape berry-related traits. The identification of the markers closely associated with these berry traits may be useful for grape molecular breeding.

Background Studies have shown that HSP20 (heat-shock protein 20) genes play important roles in regulating plant growth, development, and stress response. However, the grape HSP20 gene family has not been well studied. Results A total of 48 VvHSP20 genes were identified from the grape genome, which were divided into 11 subfamilies (CI, CII, CIII, CV, CVI, CVII, MI, MII, ER, CP and PX/Po) based on a phylogenetic analysis and subcellular localization. Further structural analysis showed that most of the VvHSP20 genes (93.8%) had no intron or only one intron, while genes that clustered together based on a phylogenetic tree had similar motifs and evolutionarily conserved structures. The HSP20s share a conservedα-crystalline domain (ACD) and the different components of the ACD domain suggest the functional diversity of VvHSP20s. In addition, the 48 VvHSP20 genes were distributed on 12 grape chromosomes and the majority of VvHSP20 genes were located at the proximal or distal ends of chromosomes. Chromosome mapping indicated that four groups of VvHSP20 genes were identified as tandem duplication genes. Phytohormone responsive, abiotic and biotic stress-responsive, and plant development-related cis-elements were identified from the cis-regulatory elements analysis of VvHSP20s. The expression profiles of VvHSP20s genes (VvHSP20–1, 11, 14, 17, 18, 19, 20, 24, 25, 28, 31, 39, 42, and 43) were largely similar between RNA-Seq and qRT-PCR analysis after hydrogen peroxide (H2O2) treatment. The results showed that most VvHSP20s were down-regulated by H2O2 treatment during fruit development. VvHSP20s genes were indeed found to be involved in the grape berry development and differences in their transcriptional levels may be the result of functional differentiation during evolution. Conclusions Our results provide valuable information on the evolutionary relationship of genes in the VvHSP20 family, which is useful for future studies on the functional characteristics of VvHSP20 genes in grape.

BackgroundEarly ripening is an important desirable attribute for fruit crops. ‘Kyoho’ is a popular table grape cultivar in many Asian countries. ‘Fengzao’ is a bud mutant of ‘Kyoho’ and ripens nearly 30 days earlier than ‘Kyoho’. To identify genes controlling early fruit development and ripening in ‘Fengzao’, RNA-Seq profiles of the two cultivars were compared at 8 different berry developmental stages in both berry peel and flesh tissues.MethodsRNA-Seq profiling of berry development between ‘Kyoho’ and ‘Fenzhao’ were obtained using the Illumina HiSeq system and analyzed using various statistical methods. Expression patterns of several selected genes were validated using qRT-PCR.ResultsAbout 447 millions of RNA-Seq sequences were generated from 40 RNA libraries covering various different berry developmental stages of ‘Fengzao’ and ‘Kyoho’. These sequences were mapped to 23,178 and 22,982 genes in the flesh and peel tissues, respectively. While most genes in ‘Fengzao’ and ‘Kyoho’ shared similar expression patterns over different berry developmental stages, there were many genes whose expression were detected only in ‘Fengzao’ or ‘Kyoho’. We observed 10 genes in flesh tissue and 22 genes in peel tissue were differentially expressed at FDR ≤ 0.05 when the mean expression of ‘Fengzao’ and ‘Kyoho’ were compared. The most noticeable one was VIT_214s0030g00950 (a superoxide dismutase gene). This ROS related gene showed lower expression levels in ‘Fengzao’ than ‘Kyoho’ in both peel and flesh tissues across various berry developmental stages with the only exception at véraison. VIT_200s0238g00060 (TMV resistance protein n-like) and VIT_213s0067g01100 (disease resistance protein at3g14460-like) were the two other noticeable genes which were found differentially expressed between the two cultivars in both peel and flesh tissues. GO functional category and KEGG enrichment analysis of DEGs indicated that gene activities related to stress and ROS were altered between the two cultivars in both flesh and peel tissues. Several differentially expressed genes of interest were successfully validated using qRT-PCR.ConclusionsComparative profiling analysis revealed a few dozens of genes which were differentially expressed in the developing berries of ‘Kyoho’ and its early ripening mutant ‘Fengzao’. Further analysis of these differentially expressed genes suggested that gene activities related to ROS and pathogenesis were likely involved in contributing to the early ripening in ‘Fengzao’.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3051-1) contains supplementary material, which is available to authorized users.

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Sequence-related amplified polymorphism (SRAP) markers were used to assess genetic relationships among 76 grape genotypes including Chinese indigenous and newly bred varieties, representatives of foreign grape varieties, and wild Vitis species. Nineteen informative primers were selected from 100 SRAP primer pairs due to their ability to produce clearly and repeatedly polymorphic and unambiguous bands among the varieties. A total of 228 bands were produced; 78.63% of them were polymorphic; the average polymorphism information content (PIC) is 0.76. Genetic relationships were obtained using Nei and Li similarity coefficients. Cluster analysis of SRAP markers through the unweighted pairgroup method of arithmetic averages (UPGMA) analysis and principal coordinate analysis (PCoA) were largely consistent. The definition of clusters in the dendrogram and PCoA plot is the same and some degree of grouping by types of grape, ecogeographical origin, and taxonomic status of the varieties was revealed. Three main groups were found after cluster analysis, i.e., table grape of Vitis vinifera; table grape of Euro-America hybrid and wine grape of V. vinifera; wild Vitis species. Groupings indicated a divergence between the table and wine-type varieties of V. vinifera. The results showed that the wild Vitis species that originated from America and China could be clearly differentiated and Vitis hancockii is the most distant from the others of Asian Vitis species. The results also indicated that SRAP markers are informative and could distinguish bud sports of grape. The present analysis revealed that Chinese cultivated and wild grape germplasm are highly variable and have abundant genetic diversity.

BackgroundMelatonin is a ubiquitous molecule and exists across kingdoms. Studies on melatonin in plants have mainly focused on its physiological influence on growth and development, and on its biosynthesis. A number of studies have been conducted on the melatonin content and exogenous melatonin treatment of grapevine (Vitis vinifera L.). However, key genes or enzymes of the melatonin biosynthetic pathway remain unclear.ResultsIn this study, we cloned and identified the gene encoding serotonin N-acetyltransferase (SNAT) in grapevine (VvSNAT2). The VvSNAT2 protein was identified from a collection of 30 members of the grapevine GCN5-related N-acetyltransferase (GNAT) superfamily. Phylogenetic and protein sublocalization analyses showed that the candidate gene VvGNAT16 is VvSNAT2. Characterization of VvSNAT2 showed that its enzymatic activity is highest at a pH of 8.8 and a temperature of 45 °C. Analysis of enzyme kinetics showed the values of Km and Vmax of VvSNAT2 using serotonin were 392.5 μM and 836 pmol/min/mg protein, respectively. The expression of VvSNAT2 was induced by melatonin treatment and pathogen inoculation. Overexpression of VvSNAT2 in Arabidopsis resulted in greater accumulation of melatonin and chlorophyll and enhanced resistance to powdery mildew in the transgenic plants compared with the wild type (WT). Additionally, our data showed that the marker genes in the salicylic acid (SA) signaling pathway were expressed to higher levels in the transgenic plants compared with the WT.ConclusionsThe VvSNAT2 gene was cloned and identified in grapevine for the first time. Our results indicate that VvSNAT2 overexpression activates the SA and JA signaling pathways; however, the SA pathway plays a central role in VvSNAT2-mediated plant defense.