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.

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.

Blueberry plants are among the most important fruit-bearing shrubs, but they have shallow, hairless roots that are not conducive to water and nutrient uptake, especially under drought conditions. Therefore, the mechanism underlying blueberry root drought tolerance should be clarified. Hence, we established a yeast expression library comprising blueberry genes associated with root responses to drought stress. High-throughput sequencing technology enabled the identification of 1475 genes potentially related to drought tolerance. A subsequent KEGG enrichment analysis revealed 77 key genes associated with six pathways: carbon and energy metabolism, biosynthesis of secondary metabolites, nucleotide and amino acid metabolism, genetic information processing, signal transduction, and material transport and catabolism. Metabolomic profiling of drought-tolerant yeast strains under drought conditions detected 1749 differentially abundant metabolites (DAMs), including several up-regulated metabolites (organic acids, amino acids and derivatives, alkaloids, and phenylpropanoids). An integrative analysis indicated that genes encoding several enzymes, including GALM, PK, PGLS, and PIP5K, modulate key carbon metabolism-related metabolites, including D-glucose 6-phosphate and β-D-fructose 6-phosphate. Additionally, genes encoding FDPS and CCR were implicated in terpenoid and phenylalanine biosynthesis, which affected metabolite contents (e.g., farnesylcysteine and tyrosine). Furthermore, genes for GST and GLT1, along with eight DAMs, including L-γ-glutamylcysteine and L-ornithine, contributed to amino acid metabolism, while genes encoding NDPK and APRT were linked to purine metabolism, thereby affecting certain metabolites (e.g., inosine and 3′,5′-cyclic GMP). Overall, the yeast functional screening system used in this study effectively identified genes and metabolites influencing blueberry root drought tolerance, offering new insights into the associated molecular mechanisms.

The NITRATE TRANSPORTER 1/PEPTIDE TRANSPORTER family (NPF) proteins play important roles in transporting substrates, such as nitrate, peptides, amino acids, dicarboxylates, malate, glucosinolates, indole acetic acid, abscisic acid, and jasmonic acid. However, there is limited information on the NPF genes in tomato (Solanum lycopersicum L.), in contrast to Arabidopsis. Our study aimed to reveal general information about tomato NPFs and to analyze the transcriptional responses of some members using plant nitrogen status. We identified 85 SlNPF genes, and a phylogenetic analysis organized them into nine major clades. Thirty motifs were found based on NPF amino acid sequence alignments. Chromosomal locations and gene duplication events of SlNPF family genes were also analyzed. An uneven distribution of SlNPF genes was discovered among tomato chromosomes. Twenty-five SlNPF genes resulted from whole-genome triplication (WGT)/segmental duplication in Solanaceae. Our results showed that ancient whole-genome triplication and tandem duplication mainly contributed to the expansion of the SlNPF genes. In the NPF family, 19 orthologous genes were identified between tomato and Arabidopsis, suggesting that at least 19 NPF genes were present in a common ancestor before Arabidopsis and tomato differentiated. In addition, we analyzed the expression patterns of the SlNPF family genes in various tomato tissues. We monitored 49 root-specific SlNPF genes that showed varied expression patterns under different N status. Among them, SINPF9, -34, ‑58 and -60 were significantly induced by both low and high levels of nitrate. Our findings provide a foundation for future research on this gene family.

Background: Blueberry (Vaccinium corymbosum L.) is one of the most important commercial fruit tree species. The development of high-quality seedlings is a prerequisite for fruit production. Stem cutting and tissue culture methods are widely applied for propagating blueberry seedlings. Both methods require adventitious roots (ARs), indicating ARs are critical for vegetative propagation. However, the underlying factors and molecular mechanisms regulating blueberry AR formation remain relatively unknown. Results: In this study, the rooting abilities of differentially lignified cuttings from various cultivars or the same cultivars cultured differently were evaluated following an indole-3-butyric acid (IBA) treatment. Field-grown semi-lignified and tissue culture-grown cuttings formed ARs, but the latter had more pericycle and secondary xylem cells and formed ARs more easily and faster. WUSCHEL-related homeobox genes are commonly involved in vascular tissue development and early root meristem maintenance. On the basis of the available Vaccinium corymbosum genome data, 29 putative WOX genes with conserved homeodomains were identified and divided into three major clades (modern/WUS, intermediate, and ancient). These 29 WOX genes were differentially expressed in the root, shoot, leaf, flower bud, and fruit. Additionally, a qRT-PCR analysis revealed that five selected VcWOX genes were responsive to an IBA treatment during AR formation. Accordingly, VcWOX4b was functionally characterized. The overexpression of VcWOX4b in transgenic tobacco inhibited AR formation by altering vascular cell division and differentiation and the indole-3-acetic acid (IAA):cytokinin (CTK) ratio. These observations suggest that VcWOX4b regulates the IAA:CTK ratio to promote primary xylem cell differentiation, thereby inhibiting AR formation. However, an IBA treatment can induce AR formation by inhibiting VcWOX4b expression. Conclusions: Current study elucidates the rooting abilities of various cultivars and the cytological characters of influence on AR formation of blueberry cuttings, which may provide novel insights into the selection of high-quality blueberry cuttings. VcWOX4b, VcWOX8/9a, VcWOX11/12c, and VcWOX13b might regulate blueberry AR formation in an IBA-dependent manner. Ectopic expression of VcWOX4b modulated the IAA:CTK ratio to promotes primary xylem cell differentiation, but inhibit secondary xylem cell differentiation, ultimately leading to decreased AR formation.