The Plant Journal最新文献

Suppressing the heading date of rice under short-day (SD) conditions while promoting it under long-day (LD) conditions can significantly enhance the regional adaptability of rice varieties. However, rice germplasm resources with these traits are scarce. In this study, we report the Jumonji C (jmjC) protein-encoding gene ISPL10. The ispl10 mutant exhibited heading 7 days later under SD and 14 days earlier under LD compared with the wild type (WT). ISPL10 decreased H3 lysine 9 dimethylation (H3K9me2) levels at the OsMADS51 locus and activated the expression of OsMADS51, which then enhanced the expression of Ehd1 and up-regulated Hd3a under SD conditions. By contrast, ISPL10 is directly bound to the promoter of OsVIL2 to suppress its expression, thereby inhibiting Ehd1 expression and reducing RFT1 expression under LD conditions. Additionally, ISPL10 interacted with Se14, another jmjC protein that controlled H3K4me3 states in the RFT1 chromatin. The field tests showed that the ispl10 mutant not only extended the growth period in low-latitude regions but also shortened the maturity duration in high-latitude regions, and thus significantly increased grain yield in both low- and high-latitude regions compared with WT. Therefore, the ISPL10 locus could be a crucial factor in improving the regional adaptability of rice varieties.

The genome data of Ocimum tenuiflorum (CIM-Ayu) were utilized for mining novel flavonoid biosynthesis-related gene(s). The search using the unannotated gene sequences yielded an uncharacterized flavonoid glucosyltransferase gene (OtUGT), which was selected for characterization. Its bioinformatics-based analysis predicted it to be an OtUGT. qRT-PCR analysis of this OtUGT indicated its highest expression in O. tenuiflorum in comparison to other Ocimum species. In O. tenuiflorum, its expression was highest in the leaf tissue compared to the trichome, stem, flower, and root. The gene expression was found to be sensitive to MeJA and light. Heterologous expression of the OtUGT protein was induced in BL21(DE3) strain of Escherichia coli. The purified recombinant protein was used for assay with different flavonoid and sugar donor substrates, whereby it showed activity only with apigenin and UDP-α-d-glucose. The product formed was apigenin 7-O-glucoside (apigetrin), which was confirmed through TLC, HPLC, LC-QTOF mass spectrometry, and NMR analyses. Transient overexpression and VIGS of OtUGT in O. tenuiflorum were appropriately reflected in terms of alterations in apigetrin levels in the plant. Apigetrin content increased by up to 2.5-fold in transgenic Nicotiana tabacum lines generated by transformation with Agrobacterium tumefaciens carrying the pBI121-OtUGT construct. Hairy roots generated from leaf explants of O. tenuiflorum through transformation with A. rhizogenes carrying the pBI121-OtUGT construct were not found to be advantageous in terms of apigetrin content. Since apigetrin possesses high medicinal value, elucidation of its biosynthesis in O. tenuiflorum will enable its economical production through optimization in the plant or heterologous systems in the future.

Flavonoids are secondary metabolites of plants that play various roles in plants. The transcriptional level regulation of flavonoid synthesis in plants has been extensively studied, but research on the protein level of flavonoid synthesis in plants is still limited. In the present study, a brown hull mutant, bh2, was screened from an ethane methyl sulfonate (EMS)-induced bank from the seeds of the indica cultivar RH2B. The bh2 mutant exhibited a brown hull phenotype and higher levels of total flavonoids and anthocyanins compared with wild-type plants. We identified the gene INHIBITOR FOR BROWN FURROWS 1 (IBF1) in the bh2 mutant through MutMap analysis and subsequently cloned it. IBF1 encodes an F-box protein and is involved in the formation of an SCF (S-phase kinase-associated protein 1 [SKP1], Cullin, and F-box) complex with the Oryza sativa SKP1-like proteins OSK1/OSK20. Through yeast two-hybrid, bimolecular fluorescence complementation, and pull-down assays, the interaction of IBF1 with chalcone synthase 1 (CHS1) was confirmed. This interaction facilitated the degradation of CHS1 through the ubiquitin-26S proteasome system. The ibf1 chs1 double mutants exhibited normal hull color, restoring the phenotype of ibf1. Genetic analysis suggested that IBF1 regulates hull color in a CHS1-dependent manner. Collectively, our study suggests that IBF1 serves as a crucial negative regulator that controls flavonoid biosynthesis by mediating CHS1 degradation, thereby regulating hull color.

The repeated evolution of high seed shattering during multiple independent de-domestications of cultivated Asian rice (Oryza sativa) into weedy rice (Oryza spp.) is a prime example of convergent evolution. Weedy rice populations converge in histological features of the abscission zone (AZ), a crucial structure for seed abscission, while ancestral cultivated rice populations exhibit varied AZ morphology and levels of shattering. However, the genetic bases of these phenotypic patterns remain unclear. We examined the expression profiles of the AZ region and its surrounding tissues at three developmental stages in two low-shattering cultivars of aus and temperate japonica domesticated groups and in two genotypes of their derived high-shattering weed groups, Blackhull Awned (BHA) and Spanish Weedy Rice (SWR), respectively. Consistent with the greater alteration of AZ morphology during the de-domestication of SWR than BHA, fewer genes exhibited a comparable AZ-region exclusive expression pattern between weed and crop in the temperate japonica lineage than in the aus lineage. Transcription factors related to the repression of lignin and secondary cell wall deposition, such as, OsWRKY102 and OsXND-1-like, along with certain known shattering genes involved in AZ formation, likely played a role in maintaining AZ region identity in both lineages. Meanwhile, most genes exhibiting AZ-region exclusive expression patterns do not overlap between the two lineages and the genes exhibiting differential expression in the AZ region between weed and crop across the two lineages are enriched for different gene ontology terms. Our findings suggest genetic flexibility in shaping AZ morphology, while genetic constraints on AZ identity determination in these two lineages.

Soil salinity remains a continuing threat to agriculture worldwide, greatly affecting seedling development and reducing crop yield. Thus, the cultivation of salt-resistant crops on salinized land is an excellent strategy to ensure food security. The rice GSK3-like protein kinase, OsGSK1, is known to play a role in the response to various abiotic stressors; however, the underlying molecular mechanism of this response remains unclear. Here, we aimed to elucidate the mechanism by which OsGSK1 regulates the salt stress response. We found that OsGSK1 interacts with OsbZIP72 to negatively regulate salt stress tolerance in rice plants. OsGSK1 is specifically induced by cold, salt stress, and abscisic acid (ABA) treatment. OsGSK1 was found to be localized in the nucleus and cytoplasm, where it physically interacts with OsbZIP72 – a positive regulator of the rice salt stress response. OsbZIP72 directly binds to the ABA response element in the OsNHX1 promoter to regulate its expression under salt stress, whereas OsGSK1 interacts with OsbZIP72 to repress OsNHX1 expression. The knockout of OsGSK1 increased salt tolerance without affecting the main agronomic traits of the mutant plants. Therefore, OsGSK1 could be used to maintain rice yield in salinized soil.

The molecular mechanisms involved in the regulation of potato tuber dormancy are complex, involving a variety of related genes and enzymes, which modulate multiple signaling pathways. Nuclear factor-Y (NF-Y) transcription factors (TFs) are widely found in eukaryotes and are involved in the regulation of plant embryonic development, seed germination, fruit ripening, and in response to biotic and abiotic stress. Previously, we found that StNF-YA8 gene expression was increasing with the release of potato tuber dormancy. In this study, it was found that StNF-YA8 overexpressed tubers broke dormancy earlier than non-transgenic (NT) and StNF-YA8 downregulated tubers. Changes in abscisic acid (ABA) and gibberellin (GA) content of different types of tubers at different dormancy periods confirmed that both GA and ABA hormones influenced the differences in dormancy time. This was confirmed by the expression of GA pathway genes StGA3ox1 and StGA20ox1 genes and ABA pathway genes StCYP707A2 and StPP2CA1 genes in different tubers. The four genes described above were further shown to be target genes of the StNF-YA8 TF, which transcriptionally activates the expression of these genes. In addition, we verified the involvement of StNF-YA8 in the tuber dormancy release process by the interacting proteins StNF-YB20 and StNF-YC5, which are able to bind to the StNF-YA8-B20-C5 module to activate the transcription of GA and ABA pathway genes. Our study reveals the StNF-YA8-C5 module activates the transcription of the StCYP707A2, StPP2CA1, StGA3ox1, and StGA20ox1 genes and alters GA and ABA content, accelerating the release of dormancy in potato tubers.

Site-specific DNA integration is an important tool in plant genetic engineering. Traditionally, this process relies on homologous recombination (HR), which is known for its low efficiency in plant cells. In contrast, Agrobacterium-mediated T-DNA integration is highly efficient for plant transformation. However, T-DNA is typically inserted randomly into double-strand breaks within the plant genome via the non-homologous end-joining (NHEJ) DNA repair pathway. In this study, we developed an approach of CRISPR/Cas9-mediated targeted T-DNA integration in Arabidopsis, which was more rapid and efficient than the HR-mediated method. This targeted T-DNA integration aided in gene activation and male germline-specific gene tagging. Gene activation was accomplished by positioning the CaMV35S promoter at the left border of T-DNA, thereby activating specific downstream genes. The activation of FT and MYB26 significantly increased their transcriptional expression, which resulted in early flowering and an altered pattern of cell wall thickening in the anther endothelium, respectively. Male germline-specific gene tagging incorporates two reporters, namely, NeoR and MGH3::mCherry, within the T-DNA. This design facilitates the creation of insertional mutants, simplifies the genetic analysis of mutated alleles, and allows for cellular tracking of male germline cells during fertilization. We successfully applied this system to target the male germline-specific gene GEX2. In conclusion, our results demonstrated that site-specific integration of DNA fragments in the plant genome can be rapidly and efficiently achieved through the NHEJ pathway, making this approach broadly applicable in various contexts.