Search

The glutathione S-transferases (GSTs, EC 2.5.1.18) constitute a versatile enzyme family with pivotal roles in plant stress responses and detoxification processes. Recent discoveries attributed the additional function of facilitating anthocyanin intracellular transportation in plants to GSTs. Our study identified 178 VcGST genes from 12 distinct subfamilies in the blueberry genome. An uneven distribution was observed among these genes across blueberry's chromosomes. Members within the same subfamily displayed homogeneity in gene structure and conserved protein motifs, whereas marked divergence was noted among subfamilies. Functional annotations revealed that VcGSTs were significantly enriched in several gene ontology and KEGG pathway categories. Promoter regions of VcGST genes predominantly contain light-responsive, MYB-binding, and stress-responsive elements. The majority of VcGST genes are subject to purifying selection, with whole-genome duplication or segmental duplication serving as key processes that drive the expansion of the VcGST gene family. Notably, during the ripening of the blueberry fruit, 100 VcGST genes were highly expressed, and the expression patterns of 24 of these genes demonstrated a strong correlation with the dynamic content of fruit anthocyanins. Further analysis identified VcGSTF8, VcGSTF20, and VcGSTF22 as prime candidates of VcGST genes involved in the anthocyanin intracellular transport. This study provides a reference for the exploration of anthocyanin intracellular transport mechanisms and paves the way for investigating the spectrum of GST functions in blueberries. [ABSTRACT FROM AUTHOR]

BRANCHED1 (BRC1) is a crucial member of the TEOSINTE BRANCHED1/CYCLOIDEA/PCF (TCP) gene family and is well known for playing a central role in shoot branching by controlling buds' paradormancy. However, the expression characteristics and molecular regulatory mechanism of BRC1 during blueberry bud dormancy are unclear. To shed light on these topics, shoots of three blueberry cultivars with different chilling requirements (CRs) were decapitated in summer to induce paradormancy release and subjected to different levels of chilling in winter to induce endodormancy release. The results showed that the high-CR cultivar 'Chandler' had the strongest apical dominance among the three cultivars; additionally, the expression of VcTCP18, which is homologous to BRC1, was the highest under both the decapitation treatment and low-temperature treatment. The 'Emerald' cultivar, with a low CR, demonstrated the opposite trend. These findings suggest that VcTCP18 plays a negative regulatory role in bud break and that there may be a correlation between the CR and tree shape. Through yeast 1-hybrid (Y1H) assays, we finally screened 21 upstream regulatory genes, including eight transcription factors: zinc-finger homeodomain protein 1/4/5/9, MYB4, AP2-like ethylene-responsive transcription factor AINTEGUMENTA (ANT), ASIL2-like, and bHLH035. It was found that these upstream regulatory genes positively or negatively regulated the expression of VcTCP18 based on the transcriptome expression profile. In summary, this study enriched our understanding of the regulatory network of BRCl during bud dormancy and provided new insights into the function of BRC1. [ABSTRACT FROM AUTHOR]

Blueberry (Vaccinium spp.) rhizosphere microorganisms can significantly increase the absorption area and improve the efficiency of rhizospheric nutrient uptake. However, there has been little research on blueberry rhizosphere microorganisms, especially those that can complement root function deficiency. In this study, we analyzed the rhizosphere fungi of 'O'Neal,' 'Sharpblue,' and 'Premier' blueberry cultivars and found that 'Premier' blueberries showed strong growth potential and relatively high root regulation ability. The dominant symbiotic fungus Sistotrema was correlated with the strong growth of 'Premier' and was directionally screened and isolated based on conserved gene structures and COG function analysis. This fungus was reinoculated onto the roots of 'Gulfcoast' and 'Star' blueberry cultivars. Sistotrema promoted the growth of blueberries and improved their ability to resist stress and grow under adverse conditions, as indicated by maintained or increased chlorophyll content under such conditions. Further analyses showed that Sistotrema has certain functional characteristics such as the ability to dissolve iron in its insoluble form and then release it, to fix nitrogen, and to inhibit nitrification in soil. Thus, it effectively doubled the soil nitrogen content and increased the soluble iron content in soil by 50%. This investigation indicates sistotrema inoculation as an approach to increase blueberry stress tolerance and complete their root nutrition deficiency. [ABSTRACT FROM AUTHOR]

MADS-box is a class of transcriptional regulators that are ubiquitous in plants and plays important roles in the process of plant growth and development. Identification and analysis of blueberry MADS-box genes can lay a foundation for their function investigations. In the present study, 249 putative MADS-box genes were identified in the blueberry genome. Those MADS-box genes were distributed on 47 out of 48 chromosomes. The phylogenetic and evolutionary analyses showed that blueberry MADS-box genes were divided into 131 type I members and 118 type II members. The type I genes contained an average of 1.89 exons and the type II genes contained an average of 7.83 exons. Motif analysis identified 15 conserved motifs, of which 4 were related to the MADS domain and 3 were related to the K-box domain. A variety of cis-acting elements were found in the promoter region of the blueberry MADS-box gene, indicating that the MADS-box gene responded to various hormones and environmental alterations. A total of 243 collinear gene pairs were identified, most of which had a Ka/Ks value of less than 1. Nine genes belonging to SEP, AP3/PI, and AGL6 subfamilies were screened based on transcriptomic data. The expression patterns of those nine genes were also verified using quantitative PCR, suggesting that VcMADS6, VcMADS35, VcMADS44, VcMADS58, VcMADS125, VcMADS188, and VcMADS212 had potential functions in blueberry fruit ripening. The results of this study provide references for an in-depth understanding of the biological function of the blueberry MADS-box genes and the mechanism of blueberry fruit ripening. [ABSTRACT FROM AUTHOR]

Plant-specific TEOSINTE BRANCHED 1, CYCLOIDEA, PROLIFERATING CELL FACTORS (TCP) transcription factors have versatile functions in plant growth, development and response to environmental stress. Despite blueberry's value as an important fruit crop, the TCP gene family has not been systematically studied in this plant. The current study identified blueberry TCP genes (VcTCPs) using genomic data from the tetraploid blueberry variety 'Draper'; a total of 62 genes were obtained. Using multiple sequence alignment, conserved motif, and gene structure analyses, family members were divided into two subfamilies, of which class II was further divided into two subclasses, CIN and TB1. Synteny analysis showed that genome-wide or segment-based replication played an important role in the expansion of the blueberry TCP gene family. The expression patterns of VcTCP genes during fruit development, flower bud dormancy release, hormone treatment, and tissue-specific expression were analyzed using RNA-seq and qRT-PCR. The results showed that the TB1 subclass members exhibited a certain level of expression in the shoot, leaf, and bud; these genes were not expressed during fruit development, but transcript levels decreased uniformly during the release of flower bud dormancy by low-temperature accumulation. The further transgenic experiments showed the overexpression of VcTCP18 in Arabidopsis significantly decreased the seed germination rate in contrast to the wild type. The bud dormancy phenomena as late-flowering, fewer rosettes and main branches were also observed in transgenic plants. Overall, this study provides the first insight into the evolution, expression, and function of VcTCP genes, including the discovery that VcTCP18 negatively regulated bud dormancy release in blueberry. The results will deepen our understanding of the function of TCPs in plant growth and development. [ABSTRACT FROM AUTHOR]

BACKGROUND: DNA methylation balance is an important regulatory mechanism for mammalian and plant development. The fruit ripening and anthocyanin accumulation of Vaccinium corymbosum are complex developmental processes that involve numerous physiological, biochemical, and structural alterations. OBJECTIVE: This study aimed to investigate the correlation of DNA methylation balance, DNA methylation and demethylation-related gene expression models and anthocyanin accumulation during blueberry fruit ripening. METHODS: The anthocyanin contents during V. corymbosum 'O'Neal' fruit development were evaluated. The V. corymbosum DNA methylation- and anthocyanin accumulation-related genes were isolated, and their relative expression patterns were detected during flower bud enlargement and fruit development. Moreover, the relative expression patterns of anthocyanin biosynthetic genes and the dynamic changes in the DNA methylation of the promoter sequences of key anthocyanin biosynthetic genes were evaluated. RESULTS: The results showed that the DNA methylation level of V. corymbosum fruit was consistent with anthocyanin accumulation during ripening, and the expression levels of anthocyanin biosynthetic and DNA methylation-related genes. CONCLUSIONS: During V. corymbosum fruit ripening, anthocyanin accumulation is regulated partially by DNA methylation balance of VcCHS and VcANS promoters. [ABSTRACT FROM AUTHOR]

Endodormancy is the stage that perennial plants must go through to prepare for the next seasonal cycle, and it is also an adaptation that allows plants to survive harsh winters. Blueberries (Vaccinium spp.) are known to have high nutritional and commercial value. To better understand the molecular mechanisms of bud dormancy release, the transcriptomes of flower buds from the southern highbush blueberry variety "O'Neal" were analyzed at seven time points of the endo- and ecodormancy release processes. Pairwise comparisons were conducted between adjacent time points; five kinds of phytohormone were identified via these processes. A total of 12,350 differentially expressed genes (DEGs) were obtained from six comparisons. Gene Ontology analysis indicated that these DEGs were significantly involved in metabolic processes and catalytic activity. KEGG pathway analysis showed that these DEGs were predominantly mapped to metabolic pathways and the biosynthesis of secondary metabolites in endodormancy release, but these DEGs were significantly enriched in RNA transport, plant hormone signal transduction, and circadian rhythm pathways in the process of ecodormancy release. The contents of abscisic acid (ABA), salicylic acid (SA), and 1-aminocyclopropane-1-carboxylate (ACC) decreased in endo- and ecodormancy release, and the jasmonic acid (JA) level first decreased in endodormancy release and then increased in ecodormancy release. Weighted correlation network analysis (WGCNA) of transcriptomic data associated with hormone contents generated 25 modules, 9 of which were significantly related to the change in hormone content. The results of this study have important reference value for elucidating the molecular mechanism of flower bud dormancy release. [ABSTRACT FROM AUTHOR]

• Identification and cloning of metal transport-related Nramp genes in blueberry. • VcNramp4 and VcNramp6 are involved in the absorption and transport of Fe by plants. • VcNramp4, VcNramp6 and VcNramp8.2 were Zn and Cd transporters in blueberry. The natural resistance-associated macrophage protein (Nramp) family comprises crucial membrane transport proteins that play vital roles in the transport and reuse of heavy metal ions in plants. Limited information is currently available on the Nramp family in blueberry (Vaccinium spp.; Vc). Elucidation of the mechanism underlying mineral-element deficiency and heavy metal toxicity in blueberry is essential for the sustainable development of the blueberry industry. In this study, three Nramp genes (VcNramp4, VcNramp6 , and VcNramp8.2) were cloned and identified from blueberry, and their functions were analyzed in transgenic Arabidopsis thaliana and yeast. Sequence analysis showed that the VcNramp genes encoded 321–455 amino acids and contained 6–8 transmembrane structural domains. Expression analysis showed that VcNramp genes were significantly up-regulated under iron (Fe) deficiency. The expression of VcNramp genes was most significantly up-regulated in the roots, by 2.05-fold relative to the control group. VcNramp4 and VcNramp6 expression in yeast and A. thaliana alleviated Fe deficiency stress. Interestingly, yeast expressing VcNramp6 showed a 1.13- to 1.38-fold increase in Fe accumulation at different medium pH levels, which was significantly higher than that of yeast expressing the other VcNramp genes. All VcNramp genes respond to changes in Fe ion concentration. Among them, VcNramp6 can effectively ameliorate Fe deficiency symptoms in plants. The expression of VcNramp genes exhibited distinct tissue specificity. Notably, the expression levels of VcNramp6 and VcNramp8.2 in the stems was only 2 %–10 % of that in the roots. The results illustrated the Fe nutrient inefficiency of blueberry. Furthermore, all identified VcNramp genes responded to mild zinc or cadmium stress, but their expression levels decreased under severe zinc or cadmium stress. [ABSTRACT FROM AUTHOR]

• Multi-isoforms of enzymes in phenolic biosynthesis were analyzed. • Multi-members of TFs in regulation of phenolic biosynthesis were analyzed. • Change of phenolics was associated with regulation of the corresponding enzymes. • Proteomic data was complementary with metabolomic data. Blueberry is one of the richest phenolic sources, providing health benefits. To study blueberry phenolic biosynthesis, we investigated phenolics and proteomics at three typical fruit maturation phases. Multiple isoforms of enzymes and multiple members of transcription factors involved in phenolic biosynthesis were divergent and differently regulated. Regulation of some proteins resulted in change of phenolic content. During fruit maturation, down-regulation of VcOMT (CUFF.177.1) and VcLAR2 (CUFF.16780.1) was associated with decreases of ferulic acid and catechin, respectively; Up-regulation of VcFLS (CUFF.41155.1), and VcF3′5′H (CUFF.51711.1) and VcF3′5′H (gene.g10884.t1.1) likely drove increases of their products (quercetin and myricetin); Up-regulation of VcUFGALT (CUFF.20951.1) and VcUFGT73 (4333_g.1) and down-regulation of VcU5GT (CUFF.51258.1) were correlated to accumulation of anthocyanins with 3-glucoside/galactoside. Additionally, four TFs, VcAPRR2 (CUFF.24826.1), VcbHLH3 (CUFF.37765.1), VcWD (CUFF.28282.2) and VcWD (CUFF.28273.1) were probably related to regulation of anthocyanin biosynthesis. These proteins were potential targets for genetic improvement in a breeding program. [ABSTRACT FROM AUTHOR]

Highlights • Nomenclature disorder of cultivars seriously affected healthy development of blueberry breeding and industry in China. • 33 Ty1/Copia and 60 Ty3/Gypsy retrotransposons were identified in blueberry genome. • Retrotransposon based SSAP were used to detect phylogenetic relationship and genetic composition of blueberry cultivars. • Lineage of some rabbiteye blueberry was supposed to be replaced progressively with repeated hybridization. • Cross breeding between genetically distant cultivars would enrich genetic diversity of blueberry. Abstract A total length of 98 070 bp long terminal repeat retrotransposon (LTR-RT) sequences were found after preliminary prediction and subsequent screening, accounting for 3.96% of the whole blueberry genome. Thirty-three members belonged to Ty1/Copia retrotransposon family and 60 members of Ty3/Gypsy retrotransposon family were identified according to their sequence similarity to previously reported retrotransposons, accounting for 1.57% and 2.39% of the whole genome, respectively. Nineteen sequences from Ty1/Copia family and thirty-three Ty3/Gypsy sequences were used for primer design. Sixty-six pairs of primers were synthesized randomly, in which forty-two pairs of primers were screened to validate the availability and transferability of LTR-RT on 48 blueberry cultivars. We found that 4, 236 bands were amplified using 42 pairs of primers, of which 4184 were polymorphic bands. Bands at each locus ranged from 34 to 219, with an average of 101. To elucidate genetic relationship of 48 blueberry cultivars, principle coordinate analysis (PCoA) was carried out based on SSAP genotyping data. The results showed that the first two coordinates could explain 14.11% of the total variation among all cultivars, of which the first and second coordinate accounted for 8.13% and 5.98% of total variation, respectively. The first three axes accounted for 18.84% of the total variation. In order to estimate genetic background and phylogenetic relationship of these cultivars, phylogenetic tree was constructed based on neighbor-joining algorithm. The results showed that 48 cultivars could be clustered into five groups, indicating that genetic background of 48 blueberry cultivars used in this study was relatively simple. The genetic composition of highbush blueberry cultivars was similar, which consisted of a single genepool. Genetic background of rabbiteye blueberry cultivars presented multiple source of genepools, which was probably related to the involvement of several species in the artificial selection. 'Bluegem' resembles genetic composition with highbush blueberries, suggesting that several cultivars possibly involved in its breeding process. The original lineage from V. virgatum was supposed to be replaced gradually with repeated hybridization during cross fertilization. The cross breeding among cultivars genetically distant from one other would enrich the genetic diversity of blueberry cultivars. All these results provided valuable references for the selection of parental cultivars in blueberry breeding. [ABSTRACT FROM AUTHOR]

Peroxisomal LON2 protease plays a pivotal role in protein quality control through its proteolysis and chaperone functions. However, little is known regarding its function in the regulation of cellular reactive oxygen species (ROS) homeostasis and in adversity tolerance in plants. To begin to assess the function of LON2, we isolated a VcLON2 cDNA from blueberry ( Vaccinium corymbosum L.), which is predicted to encode a peroxisomal protein containing a long N-terminal domain, a central AAA+ module and a C-terminal proteolytic domain. Quantitative real-time RT-PCR analysis revealed that VcLON2 was expressed ubiquitously throughout the blueberry plant including vegetative and reproductive organs, and its expression increased in older tissues. Overexpression of VcLON2 in tobacco led to increased tolerance to NaCl, PEG and heat stresses, as indicated by the lower contents of H 2 O 2 , malondialdehyde (MDA) and carbonyl groups, compared with wild type (WT). In contrast, silencing of the VcLON2 homolog, NbLON2 , in tobacco seedlings resulted in significantly higher sensitivity to various abiotic stresses. Furthermore, the activity of catalase (CAT), a peroxisomal enzyme involved in the detoxification of ROS, was found to be elevated in VcLON2 -overexpressed seedlings and conversely reduced in NbLON2 -silenced seedlings under non-stress and stress conditions, compared with WT. Our results suggest that VcLON2 plays an important role in the maintenance of the ROS-scavenging functions of peroxisomes, which is necessary for tolerance to abiotic stresses. [ABSTRACT FROM AUTHOR]

• 34 VcTIFY genes, containing the highly conserved TIFY domain, were identified from the highbush blueberry genome. • The expression patterns of VcTIFYs were significantly different throughout flower and fruit developmental processes of the large-size and small-size highbush blueberry cultivars. • Blueberry fruit size, ripening and VcTIFY gene expression levels were affected significantly by exogenous jasmonic acid. Most plant-specific TIFY proteins, the transduction hubs of jasmonic acid (JA) signals, determine transcriptional activities of JA-responsive genes, and play important regulatory roles in plant development and stress responses. In the present study, 34 TIFY genes from the highbush blueberry genome were identified, and their expression patterns during flower and fruit development and responses to exogenous JA treatment were investigated. The results showed that VcTIFY members had similar gene structures within highly conserved motifs, which were clustered into 5 main clades. Numerous phytohormone-, tissue- and development-related regulatory elements and stresses-responsive elements were widely distributed in the VcTIFY promoter regions. Gene expression analysis showed that VcTIFYs had distinct spatiotemporal expression patterns during flower enlargement and fruit development, while their expression levels were significantly different between the large-size cultivar 'O'Neal' and the small-size cultivar 'Bluerain'. Under exogenous JA treatments, the weight, horizontal diameter and ripening of mature fruit were affected to different degrees, and the expression levels of VcTIFYs varied significantly in 'O'Neal' and 'Bluerain' mature fruits, indicating that VcTIFYs might be involved in regulating blueberry fruit size and development. These results should enrich our knowledge of TIFY genes and lay the groundwork for future functional research and genetic breeding of highbush blueberry. [ABSTRACT FROM AUTHOR]