Despite recent advancements in plant molecular biology and biotechnology, providing enough, and safe, food for an increasing world population remains a challenge. The research into plant development ...and environmental adaptability has attracted more and more attention from various countries. The transcription of some genes, regulated by transcript factors (TFs), and their response to biological and abiotic stresses, are activated or inhibited during plant development; examples include, rooting, flowering, fruit ripening, drought, flooding, high temperature, pathogen infection, etc. Therefore, the screening and characterization of transcription factors have increasingly become a hot topic in the field of plant research. BLH/BELL (BEL1-like homeodomain) transcription factors belong to a subfamily of the TALE (three-amino-acid-loop-extension) superfamily and its members are involved in the regulation of many vital biological processes, during plant development and environmental response. This review focuses on the advances in our understanding of the function of BLH/BELL TFs in different plants and their involvement in the development of meristems, flower, fruit, plant morphogenesis, plant cell wall structure, the response to the environment, including light and plant resistance to stress, biosynthesis and signaling of ABA (Abscisic acid), IAA (Indoleacetic acid), GA (Gibberellic Acid) and JA (Jasmonic Acid). We discuss the theoretical basis and potential regulatory models for BLH/BELL TFs' action and provide a comprehensive view of their multiple roles in modulating different aspects of plant development and response to environmental stress and phytohormones. We also present the value of BLHs in the molecular breeding of improved crop varieties and the future research direction of the BLH gene family.
Numerous studies have been focusing on breeding tomato plants with enhanced lycopene accumulation, considering its positive effects of fruits on the visual and functional properties. In this study, ...we used a bidirectional strategy: promoting the biosynthesis of lycopene, while inhibiting the conversion from lycopene to β- and α-carotene. The accumulation of lycopene was promoted by knocking down some genes associated with the carotenoid metabolic pathway. Finally, five genes were selected to be edited in genome by CRISPR/Cas9 system using
-mediated transformation. Our findings indicated that CRISPR/Cas9 is a site-specific genome editing technology that allows highly efficient target mutagenesis in multiple genes of interest. Surprisingly, the lycopene content in tomato fruit subjected to genome editing was successfully increased to about 5.1-fold. The homozygous mutations were stably transmitted to subsequent generations. Taken together, our results suggest that CRISPR/Cas9 system can be used for significantly improving lycopene content in tomato fruit with advantages such as high efficiency, rare off-target mutations, and stable heredity.
Fruit development and ripening is regulated by genetic and environmental factors and is of critical importance for seed dispersal, reproduction, and fruit quality. Tomato (Solanum lycopersicum) ...ripening inhibitor (rin) mutant fruit have a classic ripening-inhibited phenotype, which is attributed to a genomic DNA deletion resulting in the fusion of two truncated transcription factors, RIN and MC. In wild-type fruit, RIN, a MADS-box transcription factor, is a key regulator of the ripening gene expression network, with hundreds of gene targets controlling changes in color, flavor, texture, and taste during tomato fruit ripening; MC, on the other hand, has low expression in fruit, and the potential functions of the RIN-MC fusion gene in ripening remain unclear. Here, overexpression of RIN-MC in transgenic wild-type cv Ailsa Craig tomato fruits impaired several ripening processes, and down-regulating RIN-MC expression in the rin mutant was found to stimulate the normal yellow mutant fruit to produce a weak red color, suggesting a distinct negative role for RIN-MC in tomato fruit ripening. By comparative transcriptome analysis of rin and rin 35S::RIN-MC RNA interference fruits, a total of 1,168 and 1,234 genes were identified as potential targets of RIN-MC activation and inhibition. Furthermore, the RIN-MC fusion gene was shown to be translated into a chimeric transcription factor that was localized to the nucleus and was capable of protein interactions with other MADS-box factors. These results indicated that tomato RIN-MC fusion plays a negative role in ripening and encodes a chimeric transcription factor that modulates the expression of many ripening genes, thereby contributing to the rin mutant phenotype.
Abstract
Objectives
The aim of this study is to determine the mechanism through which 1-methylcyclopropene (1-MCP) affects the quality of red ‘Fuji’ apples, which were stored for a short duration.
...Materials and Methods
Red ‘Fuji’ apples were treated with 1-MCP (1.0 μl/L), stored at 25 °C for 0, 12, 24, 48, 72, and 96 h, and ethylene production was measured. An integrated metabolomic and transcriptomic analysis was performed on apples stored for 24 h.
Results
The release of ethylene was significantly delayed from red ‘Fuji’ apples subjected to 1-MCP treatment. By performing an integrated transcriptome and metabolome analyses, we identified 117 differentially expressed genes (DEGs) and 44 differentially accumulated metabolites (DAMs). By performing functional enrichment analysis, we found that DEGs were involved in the following pathways: carbon metabolism (LPD2, gpmA, LTA2, ACC, PSAT1, MdCAS2), phytohormone signal transduction (EBF1), amino acid metabolism (MdACS-1), fatty acid metabolism (LOX1.5, KCS4, KAS1), energy metabolism (Lhcb1, Lhcb6, PsbY, GPDHC1, PUMP5), metabolic pathways (TRE1, HEXO1) and cell wall metabolism (CSLG2). Thus, these DEGs were involved in the ripening of fruits, and they controlled the quality of fruits at the post-harvest stage. The metabolites were enriched with DAMs. These were found to be individually involved in the metabolic pathway, secondary metabolite biosynthesis, phenylpropanoid biosynthesis, flavonoids, and flavonol synthesis.
Conclusions
The results indicate that 1-MCP inhibits the biosynthesis of ethylene and suppresses energy metabolism. Moreover, it also downregulates metabolic pathways and the enzymatic genes related to fruit quality. Therefore, 1-MCP delays the ripening of fruits at the post-harvest stage. This study helps us understand how 1-MCP treatment affects the ripening and quality of fruits.
Fruit ripening is a complex biological process affecting fruit quality. In tomato the fruit ripening process is delicately regulated by transcription factors (TFs). Among these, the TOMATO ...AGAMOUS-LIKE 1 (TAGL1) gene plays an important role in both the development and ripening of fruit. In this study, the TAGL1 gene was successfully silenced by virus-induced gene silencing technology (VIGS), and the global gene expression and metabolites profiles of TAGL1-silenced fruits were analyzed by RNA-sequence analysis (RNA-seq) and liquid chromatography-mass spectrometry (LC-MS/MS). The TAGL1-silenced fruits phenotypically displayed an orange pericarp, which was in accordance with the results expected from the down-regulation of genes associated with carotenoid synthesis. Levels of several amino acids and organic acids were lower in the TAGL1-silenced fruits than in the wild-type fruits, whereas, α-tomatine content was greatly increased (more than 10-fold) in the TAGL1-silenced fruits compared to wild-type fruits. The findings of this study showed that TAGL1 not only regulates the ripening of tomato fruits, but also affects the synthesis and levels of nutrients in the fruit.
Due to the presence of bioactive compounds, fruits are an essential part of people’s healthy diet. However, endogenous ethylene produced by climacteric fruits and exogenous ethylene in the ...microenvironment could play a pivotal role in the physiological and metabolic activities, leading to quality losses during storage or shelf life. Moreover, due to the variety of fruits and complex scenarios, different ethylene control strategies need to be adapted to improve the marketability of fruits and maintain their high quality. Therefore, this study proposed an ethylene dynamic monitoring based on multi-strategies control to reduce the post-harvest quality loss of fruits, which was evaluated here for blueberries, sweet cherries, and apples. The results showed that the ethylene dynamic monitoring had rapid static/dynamic response speed (2 ppm/s) and accurately monitoring of ethylene content (99% accuracy). In addition, the quality parameters evolution (firmness, soluble solids contents, weight loss rate, and chromatic aberration) showed that the ethylene multi-strategies control could effectively reduce the quality loss of fruits studied, which showed great potential in improving the quality management of fruits in the supply chain.
Fruit softening that occurs during fruit ripening and postharvest storage determines the fruit quality, shelf life and commercial value and makes fruits more attractive for seed dispersal. In ...addition, over-softening results in fruit eventual decay, render fruit susceptible to invasion by opportunistic pathogens. Many studies have been conducted to reveal how fruit softens and how to control softening. However, softening is a complex and delicate life process, including physiological, biochemical and metabolic changes, which are closely related to each other and are affected by environmental conditions such as temperature, humidity and light. In this review, the current knowledge regarding fruit softening mechanisms is summarized from cell wall metabolism (cell wall structure changes and cell-wall-degrading enzymes), plant hormones (ETH, ABA, IAA and BR et al.), transcription factors (MADS-Box, AP2/ERF, NAC, MYB and BZR) and epigenetics (DNA methylation, histone demethylation and histone acetylation) and a diagram of the regulatory relationship between these factors is provided. It will provide reference for the cultivation of anti-softening fruits.
Tomato is abundant in alkaloids, phenolic acids, and flavonoids; however, the effect of transcription factor NOR-like1 on these metabolites in tomato is unclear. We used a combination of widely ...targeted metabolomics and transcriptomics to analyze wild-type tomatoes and CR-NOR-like1 tomatoes. A total of 83 alkaloids, 85 phenolic acids, and 96 flavonoids were detected with significant changes. Combined with a KEGG enrichment analysis, we revealed 16 differentially expressed genes (DEGs) in alkaloid-related arginine and proline metabolism, 60 DEGs were identified in the phenolic acid-related phenylpropane biosynthesis, and 30 DEGs were identified in the flavonoid-related biosynthesis pathway. In addition, some highly correlated differential-expression genes with differential metabolites were further identified by correlation analysis. The present research provides a preliminary view of the effects of NOR-like1 transcription factor on alkaloid, phenolic acid, and flavonoid accumulation in tomatoes at different ripening stages based on widely targeted metabolomics and transcriptomics in plants, laying the foundation for extending fruit longevity and shelf life as well as cultivating stress-resistant plants.
MicroRNAs (miRNAs), a ubiquitous class of short RNAs, play vital roles in physiological and biochemical processes in plants by mediating gene silencing at post-transcriptional (PTGS) level. Tomato is ...a model system to study molecular basis of fleshy fruit ripening and senescence, ethylene biosynthesis and signal transduction owing to its genetic and molecular tractability. To study the functions of miRNAs in tomato fruit ripening and senescence, and their possible roles in ethylene response, the next generation sequencing method was employed to identify miRNAs in tomato fruit. Bioinformatics and molecular biology approaches were combined to profile the miRNAs expression patterns at three different fruit ripening stages and by exogenous ethylene treatment.
In addition to 7 novel miRNA families, 103 conserved miRNAs belonging to 24 families and 10 non-conserved miRNAs matching 9 families were identified in our libraries. The targets of many these miRNAs were predicted to be transcriptional factors. Other targets are known to play roles in the regulation of metabolic processes. Interestingly, some targets were predicted to be involved in fruit ripening and softening, such as Pectate Lyase, beta-galactosidase, while a few others were predicted to be involved in ethylene biosynthesis and signaling pathway, such as ACS, EIN2 and CTR1. The expression patterns of a number of such miRNAs at three ripening stages were confirmed by stem-loop RT-PCR, which showed a strong negative correlation with that of their targets. The regulation of exogenous ethylene on miRNAs expression profiles were analyzed simultaneously, and 3 down-regulated, 5 up-regulated miRNAs were found in this study.
A combination of high throughput sequencing and molecular biology approaches was used to explore the involvement of miRNAs during fruit ripening. Several miRNAs showed differential expression profiles during fruit ripening, and a number of miRNAs were influenced by ethylene treatment. The results suggest the importance of miRNAs in fruit ripening and ethylene response.
Summary
The development and ripening of tomato fruit are complex processes involving many gene regulatory pathways at the transcriptional and post‐transcriptional level. Ripening inhibitor (RIN) is a ...vital transcription factor, which targets numerous ripening‐related genes at the transcriptional level during tomato fruit ripening. MicroRNAs (miRNAs) are a class of short noncoding RNAs that play important roles in post‐transcriptional gene regulation. To elucidate the potential regulatory relationship between rin and miRNAs during fruit development and ripening, we identified known miRNAs and profiled their expression in wild‐type tomato and rin mutant using a deep sequencing approach combined with quantitative RT‐PCR. A total of 33 known miRNA families were identified, of which 14 miRNA families were differently accumulated. Subsequent promoter analysis showed that possible RIN‐binding motifs (CArG‐box) tended to occur frequently in the promoter regions of partial differently expressed miRNAs. In addition, ethylene may participate in the regulation of miRNAs accumulation during tomato fruit ripening. Chromatin immunoprecipitation (ChIP) and electrophoretic mobility shift assay confirmed the direct binding of RIN to the promoter of MIR172a. Collectively, these results showed a close correlation between miRNA expression and RIN as well as ethylene, which further elucidated the regulatory roles of miRNAs during fruit development and ripening and enriched the regulatory network of RIN in tomato fruit.
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