Current Plant Biology最新文献

Tobacco (Nicotiana tabacum) is known for its psychoactive alkaloid nicotine, which presents significant public health challenges. Recent research has linked the final stages of nicotine biosynthesis with the BBL and A622 genes, yet this part of the biosynthetic pathway remains largely unexplored, representing a 'black box' in our understanding. In our study, we employed a multi-target CRISPR/Cas9 system to target homologous genes of BBL and A622 in commercial tobacco varieties Virginia, creating various mutants. This led to significant variations in plant development and alkaloid content. Notably, mutant lines a622a-38–5 and a622l-3–9 with exon-intron boundary deletions exhibited significantly decreased plant height and leaf number, along with a substantial reduction in alkaloids, including nicotine. Particularly, double mutants in the A622 family displayed more severe effects than sextuple BBL mutants, emphasizing the distinctive role of A622 in nicotine synthesis and plant development. Our findings demonstrate that mutations in A622 and BBL genes can drastically reduce nicotine and anatabine content, with some cases showing reductions up to 99.6%. These results underscore the potential of genome editing in developing tobacco varieties with significantly lower nicotine levels. This study not only enhances our understanding of nicotine biosynthesis but also contributes to public health efforts by providing a pathway to develop less addictive tobacco products.

The complete exploitation of Brassica napus plants is a study hotspot, since it is an essential oil crop that is widely cultivated across the world. Glucosinolate is a unique secondary metabolite in the Brassicaceae family, and its content has a substantial influence on rapeseed development and quality. Its degradation products have various physiological functions, among which Nitrile specific proteins (NSPs) can hydrolyze glucosinolate and hence influence the balance of plant immunity and growth. However, the related gene families in B. napus have not been investigated. Here, 72 NSP family members were discovered and described in B. napus based on their sequence structures, physiological correlations, phonological locations, and expression levels. According to collinearity studies, the NSP proteins in B. napus and A. thaliana are closely related. Analysis of BnNSP expression patterns in various tissues revealed that BnNSPs exhibit high tissue specificity, implying that BnNSPs may play distinguish functions in various developmental phases. We discovered that NSPs may be regulated by hormones such as abscisic acid (ABA), gibberellin (GA), and metallic jasmonate (MeJA) based on the expression of NSPs during hormone treatment. The results provide valuable information for the future functional characterization of BnNSP genes.

MYB4, a member of the R2R3-type subfamily of MYB transcription factor plays a crucial role in regulating the accumulation of UV-B absorbing phenylpropanoids in plants. UV-B exposure for a longer duration down-regulates the expression of MYB4 gene in Arabidopsis. MYB4 protein represses its own expression by binding to its own promoter. However, at present practically nothing is known about the post-translational regulation of MYB4 protein in vivo. Here, we provide evidence that in Arabidopsis MYB4 protein is phosphorylated in vivo and is targeted by the ubiquitin-26S proteasome-dependent pathway. Immunoprecipitation, immunoblotting, and phosphoprotein staining experiments have revealed that both the accumulation pattern and phosphorylation of MYB4 increase in the light condition during the 24 hours time span under long-day conditions. Yeast two-hybrid and bimolecular fluorescence complementation assays have shown that MYB4 directly interacts with a nuclear WD40 repeat protein, PRL1 in vivo. Cell-free protein degradation assay in the absence and presence of proteasome inhibitor indicates that MYB4 is degraded in a ubiquitin proteasome-dependent manner. Furthermore, analyses of MYB4 protein accumulation levels in transgenic atmyb4–1 mutant line expressing 35 S:AtMYB4 (35 S:AtMYB4-atmyb4–1) and atprl1–1 mutant line indicate that PRL1 regulate stability of MYB4 in Arabidopsis. Overall, our results provide important information on the possible mechanism of post-translational modification and regulation of stability of MYB4 protein in Arabidopsis in vivo.

Dehydrins (DHNs) are essential proteins in the embryonic development and abiotic stress responses of plants. Due to their remarkable ability to confer tolerance to plants in conditions of drought, salinity and extreme temperatures, DHNs have garnered considerable interest. Quinoa (Chenopodium quinoa Willd.), a facultative halophyte plant, can thrive in a wide range of agroecosystems, making it a promising candidate for stress tolerance studies. In this study, we identified eleven DHN genes in the quinoa genome belonging to Y-, F- and H-orthologous groups found in angiosperms. Notably, the H-DHNs lack the K-segment, a feature observed in all Amaranthaceae species, but not in other angiosperms. We identified four DHN structural subgroups: FSKn, YnSKn, SKn-DHNs and the atypical HS-DHN. Phylogenetic analysis indicated that each structural subgroup, except for SK2-DHN, presents two paralogous genes, in accordance with the allotetraploid character of C. quinoa. Quantitative real-time PCR expression analysis revealed that DHN1s (FSK2) and DHN3s (Y2SK2) were expressed in all tissues, while DHN2s (FSK3) were predominant in roots and DHN4s (Y4SK2 and SK2) were predominant in flowers. Salt-response gene expression analysis in seedlings showed that CqDHN4s increase their expression in response to salt stress in all varieties studied, while CqDHN1s reduce their expression in a more salt stress-tolerant variety, suggesting a possible adaptive advantage. In silico analysis of the promoters of CqDHN1s and CqDHN4s supports the involvement of these DHNs in responding to abiotic stress.

Plant tissue culture plays a central role in the agricultural, horticultural, research, and conservation sectors. It facilitates precise control over plant propagation and manipulation, resulting in enhanced crop yields, effective disease management, and the preservation of endangered plant species. Browning, a well-acknowledged limitation in plant tissue culture, poses potential challenges to successful in vitro plant multiplication. Browning primarily occurs in response to enzymatic reactions due to explant damage. Left untreated, it can lead to a reduced in the regeneration capacity, hindered callus proliferation, impeded development of adventitious shoots, and, in extreme cases, tissue necrosis. To mitigate the issue of browning, several in vitro strategies have been implemented i.e., submerging the explants in specialized solutions designed to inhibit browning, incorporating anti-browning agents into the growth medium, and adhering to certain cultural techniques. This article aims to comprehensively examine the factors contributing to browning and the multitude of strategies employed to effectively manage browning problems in plant tissue cultures. Furthermore, it explores the potential of encapsulating natural products as a cutting-edge method for addressing browning in plant tissue culture. These innovative approaches offer promising avenues for controlling browning in plant tissue culture, thereby contributing to the advancement of sustainable agricultural practices and conservation efforts.

Soil alkalinity due to the accumulation of alkaline salts greatly impairs crop production. Despite advancements in crop stress response studies through metabolomic analyses, limited progress has been made in understanding cultivar differences in alkali tolerance due to the scarcity of suitable genetic material. This study aimed to characterize the metabolic responses to alkali stress in two rice cultivars, Kasalath (alkali-sensitive) and Gharib (alkali-tolerant), which were screened in an alkali soil field. A metabolomic analysis of the responses of hydroponically grown seedlings of both cultivars to alkaline and neutral salt stress was performed. Under alkali stress, the tolerant cultivar Gharib showed a significant accumulation of metabolites from the TCA organic acid and arginine synthesis pathways. This accumulation is consistent with observations in alkaliphilic wild grasses and may account for the superior alkali tolerance of Gharib. Although amino acids and nitrogen-containing metabolites, such as asparagine and allantoin, also accumulated under alkali stress, their accumulation was not specific to alkali stress, as previously reported. They accumulated similarly in both Kasalath and Gharib, suggesting that while these metabolites may alleviate alkali stress, they are unlikely to be responsible for cultivar differences in rice alkali tolerance.

Stone apple (Aegle marmelos L.) is a subtropical fruit tree of the Rutaceae family, highly valued in traditional medicine across the Indian subcontinent. We conceived this study with the objective of developing a comprehensive transcriptome dataset, identifying SSRs for marker-assisted breeding, and delineating regulators of gene expression, with a specific emphasis on non-coding RNA (ncRNA), particularly related to drought stress. To achieve this, RNA-seq was conducted using RNA pooled from various tissues, including roots, leaves, inflorescence, and developing seeds from stone apple, and the clean reads were assembled into 40,886 unigenes. Subsequently, the unigenes were categorized into gene ontology categories encompassing biological processes, molecular functions, and cellular components. Within the unigenes, we identified a total of 9174 perfect simple sequence repeats (SSRs), 2167 transcription factors (TFs) distributed among 69 families, and 415 transcription regulators (TRs) across 27 families. Additionally, 19 microRNAs (miRNAs) from 12 families, 16,811 potential long noncoding RNAs (lncRNAs), and six functional endogenous target mimics (eTMs) were detected. Analysis of lncRNA-miRNA-mRNA interactions unveiled multiple regulatory nodes, elucidating lncRNA/miRNA-driven gene expression control in stone apple. The increased co-expression of selected drought-related lncRNAs and their cognate target mRNAs supported the aforementioned findings under drought conditions. Overall, this study significantly advances our understanding of stone apple genomics and lays a foundation for future omics-based studies, thereby facilitating the deployment of climate-resilient strategies in the species.

This research delves into phenylpropanoid metabolism, focusing on phenylpropene biosynthesis in the methyleugenol chemotype of basil (Ocimum basilicum L.). We isolated peltate glandular trichomes (PGTs) from basil leaves to eliminate primary metabolic influences, offering a unique perspective into these complex processes. Vermicompost, chosen for its eco-friendly composition and superiority in invigorating phenylpropanoid metabolism. In this study, we investigated the impacts of solid and tea-form vermicompost applications at 0%, 10%, and 25% doses on the methyleugenol chemotype of basil, focusing on the expression levels of PAL, 4CL, EGS, EOMT, and CVOMT genes and phenylpropene accumulation in the peltate glandular trichomes. Results showed that 10% solid vermicompost (SV) application increased 4CL expression level at 236%, while 25% SV application further enhanced EOMT and CVOMT expressions to towering values by 7,494-fold and 19,643-fold, respectively. SV applications did not significantly impact eugenol accumulation but suppressed chavicol biosynthesis. Methyleugenol and methylchavicol accumulation rose in a dose-dependent manner, with significant increases observed in the 25% SV application. A positive correlation was found between CVOMT expression and accumulation rates of methyleugenol and methylchavicol phenylpropenes following SV applications. Conversely, vermicompost tea (VT) applications led to mixed gene expression patterns and reduced eugenol and methyleugenol ratios in peltate glandular trichomes compared to control. In summary, the notably high gene expressions observed in the results of our preliminary study offer a new perspective in the field of phenylpropanoid metabolism. This underscores the value of utilizing single-cell type PGTs for examining secondary metabolic pathways in plants and demonstrates the impact of vermicompost on phenylpropene production.

The process of alternative splicing (AS) has emerged as a crucial mechanism in plant responses to environmental stresses, contributing to the enhancement of the required transcriptome and proteome complexity. Despite the importance of AS, there remains a paucity of studies on the regulatory implications of AS in the responses of wheat to salt stress. In the current study, transcriptome-wide changes in AS profiles were established in roots and shoots of Najran wheat treated with 200 mM NaCl. Salt stress induced AS events increasing the complexity of the transcriptome; out of all expressed genes in all samples, 32,268 genes (22.5% of expressed genes) in the roots and 31,941 genes (23.1% of expressed genes) in the shoots were subjected to AS with 3’ Alternative splice site (A3) being the most frequent AS event and mutually exclusive exon (MX) being the least common event. Moreover, the results revealed that salt stress modulates AS patterns in a tissue-specific way where 82% of AS events were differentially expressed in either root or shoot tissues, participating in organ differentiation. In Total, 423 Differential AS events associated with cytoskeletal-related categories such as microtubule-based processes, actin filament-based movements, and cytoskeletal motor activity were identified in the roots. In contrast, 393 Differential AS events associated with biological categories related to metabolic and signalling processes such as catabolic processes, and response to gibberellin were identified in the shoots. The results presented in this study enhance our understanding of salt tolerance mechanisms in wheat and provide promising insights for future functional investigations and crop improvement efforts.