Search Results (10)

Flower senescence is a key physiological constraint on the ornamental and commercial longevity of cut roses. Although abscisic acid (ABA) is recognized as a promoter of this process, the molecular circuitry through which ABA operates, particularly the specific contributions of MYB transcription factors, remains largely unexplored. In this study, we identify RcMYB002 as a negative regulator of rose flower senescence. Transient overexpression of RcMYB002 significantly delays senescence, preserves anthocyanin accumulation, and modulates antioxidant enzyme activities in a time-dependent manner, consequently attenuating ABA-triggered oxidative stress. In contrast, silencing RcMYB002 accelerates senescence-associated phenotypes. At the molecular level, ABA suppresses RcMYB002 transcript accumulation, while yeast one-hybrid (Y1H) assays indicate that RcMYB002 interacts with the promoter regions of senescence-associated genes SAG12 and SAG21, consistent with a role in their transcriptional regulation. Taken together, our results support a model in which ABA promotes flower senescence by downregulating RcMYB002, thereby derepressing downstream senescence-executing genes. This work provides a molecular basis for understanding flower senescence and offers a potential target for extending rose vase life. Full article

Ricinus communis is a significant economic crop, where plant height and stress tolerance are critical factors influencing both yield and quality. The variation in plant height is influenced by both genetic and environmental factors, with environmental stresses such as salt, drought, and cold notably affecting plant growth phenotypes. In this study, we utilized transcriptome data from two varieties, DL01 and Hale, which differ in plant height, to systematically identify the RcMYB transcription factor family and screen 12 key RcMYBs associated with height variation. We also analyzed the expression patterns of these genes under various stress conditions, including salt, drought, cold, and heat. Notably, these 12 height/stress-related RcMYB genes such as RcMYB45 and RcMYB27 showed notable expression changes in response to different stress treatments, suggesting their pivotal roles in regulating both plant height and stress tolerance. Through protein–protein interaction (PPI) network analysis, we further discovered that these RcMYBs could interact with several regulatory factors. This study highlights the roles of RcMYB regulators in controlling plant height and stress adaptation in R. communis, providing potential target genes for molecular breeding and offering valuable insights into improving growth performance and stress tolerance. Full article

In plants, the R2R3-MYB transcription factors are one of the largest MYB gene families. These MYB transcription factors are very important for regulating plant growth and development. RcMYB114, RcbHLH, and RcWD40 promote anthocyanin accumulation by forming the MBW (MYB-bHLH-WD40) complex and determine the rose flower’s color. RcMYB114 genomic sequences differ between the red petal and white varieties. Two non-synonymous substitutions were found in the open reading frame. It leads to a change in amino acids. Here, the anthocyanin content showed that there was no anthocyanin in white petals, while the anthocyanin content in red petals increased firstly at stage 2, decreased slightly at stage 4, and then increased again at stage 5. The spatiotemporal expression pattern analysis showed that RcMYB114 was not expressed in all petals and tissues of white petals at different flower development stages. In red petal varieties, RcMYB114 was highly expressed in petals, followed by styles, and not expressed in stems, young leaves, and stage 1 of flower development. However, RcMYB114 has the highest expression level at the blooming stage. The RcMYB114 sequence contains 9 SNPs in the coding region, 7 of which were synonymous substitutions that had no effect on the translation product and 2 of which were non-synonymous substitutions that resulted in amino acid alteration at positions 116 and 195, respectively. The RcMYB114 gene in red rose was named RcMYB114a, and in white rose was RcMYB114b. RcMYB114c was mutated into leucine via artificial mutation; it was valine at position 116 of RcMYB114a, and Glycine mutated into Arginine at position 195 of RcMYB114a was RcMYB114d. RcMYB114b was the double mutation at positions 116 and 195 of RcMYB114a. The results of yeast two-hybrid experiments showed that RcMYB114a and its missense mutations RcMYB114b, RcMYB114c, and RcMYB114d could both interact with RcbHLH and RcWD40 to form the MYB-bHLH-WD40 complex. A transient transformation experiment in tobacco confirmed that RcMYB114a and its missense mutations RcMYB114b, RcMYB114c, and RcMYB114d could significantly promote the high expression of related structural genes in tobacco, together with the RcbHLH gene, which led to the accumulation of anthocyanins and produced the red color of the leaves. The RcMYB114a gene and its missense mutations RcMYB114b, RcMYB114c, and RcMYB114d interacted with the RcbHLH gene and significantly regulated the accumulation of anthocyanins. The two non-synonymous mutations of RcMYB114 do not affect the function of the gene itself, but the content of the anthocyanins accumulated was different. This study should provide clues and references for further research on the molecular mechanism underlying the determination of rose petal color. Full article

Elevated levels of reactive oxygen species (ROS) are caused by ultraviolet B radiation (UV-B) stress. In response, plants strengthen their cell membranes, impeding photosynthesis. Additionally, UV-B stress initiates oxidative stress within the antioxidant defense system and alters secondary metabolism, particularly by increasing the quantity of UV-absorbing compounds such as flavonoids. The v-myb avian myeloblastosis viral oncogene homolog (MYB) transcription factor (TF) may participate in a plant’s response to UV-B damage through its regulation of flavonoid biosynthesis. In this study, we discovered that the photosynthetic activity of Rhododendron chrysanthum Pall. (R. chrysanthum) decreased when assessing parameters of chlorophyll (PSII) fluorescence parameters under UV-B stress. Concurrently, antioxidant system enzyme expression increased under UV-B exposure. A multi-omics data analysis revealed that acetylation at the K68 site of the RcTRP5 (telomeric repeat binding protein of Rhododendron chrysanthum Pall.) transcription factor was upregulated. This acetylation modification of RcTRP5 activates the antioxidant enzyme system, leading to elevated expression levels of peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT). Upregulation is also observed at the K95 site of the chalcone isomerase (CHI) enzyme and the K178 site of the anthocyanidin synthase (ANS) enzyme. We hypothesize that RcTRP5 influences acetylation modifications of CHI and ANS in flavonoid biosynthesis, thereby indirectly regulating flavonoid production. This study demonstrates that R. chrysanthum can be protected from UV-B stress by accumulating flavonoids. This could serve as a useful strategy for enhancing the plant’s flavonoid content and provide a valuable reference for research on the metabolic regulation mechanisms of other secondary substances. Full article

MYB-related transcription factors (TFs) subfamily is a subfamily of MYB TFs, which are mainly involved in plant secondary metabolism, growth and development, and stress response. To explore the function of MYB-related subfamily genes in Rosa chinensis, this study systematically analyzed characters of the MYB-related subfamily members in R. chinensis with bioinformatic analysis using the genomic data of R. chinensis and investigated their expression characteristics using quantitative real-time PCR (qRT-PCR). The results show that 100 MYB-related proteins were identified in R. chinensis. Proteins are mainly found in the nucleus. Chromosome localization revealed that all MYB-related genes are mapped to seven chromosomes and are distributed in clusters. Collinear analysis shows that 13 pairs of MYB-related genes had a collinear relationship, indicating R. chinensis may have evolved its MYB-related subfamily gene through fragment duplication. The analysis of motifs and conserved domains shows that Motif 3 is the most conserved motif. There are numerous ABA and MeJA response elements in MYB-related genes. ABA and MeJA treatments significantly shortened the vase life of R. chinensis, while the flower diameter on day 3 was the largest, suggesting that ABA and MeJA might induce MYB-related gene expression during cut flower senescence. The expression of MYB-related genes is tissue specific, most of which show the highest expression levels in petals. Notably, among six plant growth regulator treatments, ABA treatment significantly increased RcMYB002 expression in R. chinensis, suggesting that RcMYB002 may be a crucial gene for ABA response. This study provides a reference for further research on the function of MYB-related genes in R. chinensis. Full article

UV-B stress destroys the photosynthetic system of Rhododendron chrysanthum Pall. (R. chrysanthum), as manifested by the decrease of photosynthetic efficiency and membrane fluidity, and also promotes the accumulation of lignin. The MYB (v-myb avian myeloblastosis viral oncogene homolog) family of transcription factors can be involved in the response to UV-B stress through the regulation of lignin biosynthesis. This study indicated that both the donor and recipient sides of the R. chrysanthum were significantly damaged based on physiological index measurements made using OJIP curves under UV-B stress. The analysis of bioinformatics data revealed that the RcTRP5 transcription factor exhibits upregulation of acetylation at the K68 site, directly regulating the biosynthesis of lignin. Additionally, there was upregulation of the K43 site and downregulation of the K83 site of the CAD enzyme, as well as upregulation of the K391 site of the PAL enzyme. Based on these findings, we conjectured that the RcTRP5 transcription factor facilitates acetylation modification of both enzymes, thereby indirectly influencing the biosynthesis of lignin. This study demonstrated that lignin accumulation can alleviate the damage caused by UV-B stress to R. chrysanthum, which provides relevant ideas for improving lignin content in plants, and also provides a reference for the study of the metabolic regulation mechanism of other secondary substances. Full article

Castor (Ricinus communis L.) seeds produce abundant ricinoleic acid during seed maturation, which is important for plant development and human demands. Ricinoleic acid, as a unique hydroxy fatty acid (HFA), possesses a distinct bond structure that could be used as a substitute for fossil fuels. Here, we identified all homologous genes related to glycolysis, hydroxy fatty acid biosynthesis, and triacylglycerol (TAG) accumulation in castor seeds. Furthermore, we investigated their expression patterns globally during five seed development stages. We characterized a total of 66 genes involved in the glycolysis pathway, with the majority exhibiting higher expression levels during the early stage of castor bean seed development. This metabolic process provided abundant acetyl-CoA for fatty acid (FA) biosynthesis. Subsequently, we identified 82 genes involved in the processes of de novo FA biosynthesis and TAG assembly, with the majority exhibiting high expression levels during the middle or late stages. In addition, we examined the expression patterns of the transcription factors involved in carbohydrate and oil metabolism. For instance, RcMYB73 and RcERF72 exhibited high expression levels during the early stage, whereas RcWRI1, RcABI3, and RcbZIP67 showed relatively higher expression levels during the middle and late stages, indicating their crucial roles in seed development and oil accumulation. Our study suggests that the high HFA production in castor seeds is attributed to the interaction of multiple genes from sugar transportation to lipid droplet packaging. Therefore, this research comprehensively characterizes all the genes related to glycolysis, fatty acid biosynthesis, and triacylglycerol (TAG) accumulation in the castor and provides novel insight into exploring the genetic mechanisms underlying seed oil accumulation in the endosperm of castor beans. Full article

Ultraviolet-B (UV-B) radiation is a significant environmental factor influencing the growth and development of plants. MYBs play an essential role in the processes of plant responses to abiotic stresses. In the last few years, the development of transcriptome and acetylated proteome technologies have resulted in further and more reliable data for understanding the UV-B response mechanism in plants. In this research, the transcriptome and acetylated proteome were used to analyze Rhododendron chrysanthum Pall. (R. chrysanthum) leaves under UV-B stress. In total, 2348 differentially expressed genes (DEGs) and 685 differentially expressed acetylated proteins (DAPs) were found. The transcriptome analysis revealed 232 MYB TFs; we analyzed the transcriptome together with the acetylated proteome, and screened 4 MYB TFs. Among them, only RcMYB44 had a complete MYB structural domain. To investigate the role of RcMYB44 under UV-B stress, a homology tree was constructed between RcMYB44 and Arabidopsis MYBs, and it was determined that RcMYB44 shares the same function with ATMYB44. We further constructed the hormone signaling pathway involved in RcMYB44, revealing the molecular mechanism of resistance to UV-B stress in R. chrysanthum. Finally, by comparing the transcriptome and the proteome, it was found that the expression levels of proteins and genes were inconsistent, which is related to post-translational modifications of proteins. In conclusion, RcMYB44 of R. chrysanthum is involved in mediating the growth hormone, salicylic acid, jasmonic acid, and abscisic acid signaling pathways to resist UV-B stress. Full article

Scent is the key character of the horticultural ornamental plant rose, and benzenoid–phenylpropanoid compounds are the main source of scent. However, the underlying biosynthesis mechanism of these benzenoid–phenylpropanoid scent metabolites during Rosa flowering is poorly understood. In this study, the volatile metabolome and transcriptome conjoint analysis was conducted on the six stages petals of the variety ‘Lanxing’ to investigate the synthesis of benzenoid–phenylpropanoid metabolites. A total of 25 benzenoid–phenylpropanoid volatile compounds were identified, of which eugenol possessed the highest content. Meanwhile, transcriptome analysis produced 87.9 million clean reads and 22,004 differentially expressed genes (DEGs). Group pairwise comparison of gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis found DEGs were enriched into phenylpropanoid compound synthesis related pathway. Weighted gene co-expression network analysis (WGCNA) found a MEgreenyellow gene module (650 DEGs) correlated with phenylpropanoid compounds. Based on the eugenol content variation and gene spatio-temporal expression, a key candidate gene RcEGS32 related to the synthesis of eugenol was identified. Co-expression network analysis found that five transcription factors, RcMYB1, RcBES1, RcERF2, RcbHLH1, and RcTUB, may act as regulators in the eugenol synthesis process by directly binding to RcEGS32 or forming a complex unit. This study provided key insights into the formation of the scent substance eugenol during flowering, offering a valuable volatile metabolome and transcriptome resource for the future target trait-related gene discovery of roses. Full article

Rosa chinensis, an important ancestor species of Rosa hybrida, the most popular ornamental plant species worldwide, produces flowers with diverse colors and fragrances. The R2R3-MYB transcription factor family controls a wide variety of plant-specific metabolic processes, especially phenylpropanoid metabolism. Despite their importance for the ornamental value of flowers, the evolution of R2R3-MYB genes in plants has not been comprehensively characterized. In this study, 121 predicted R2R3-MYB gene sequences were identified in the rose genome. Additionally, a phylogenomic synteny network (synnet) was applied for the R2R3-MYB gene families in 35 complete plant genomes. We also analyzed the R2R3-MYB genes regarding their genomic locations, Ka/Ks ratio, encoded conserved motifs, and spatiotemporal expression. Our results indicated that R2R3-MYBs have multiple synteny clusters. The RcMYB114a gene was included in the Rosaceae-specific Cluster 54, with independent evolutionary patterns. On the basis of these results and an analysis of RcMYB114a-overexpressing tobacco leaf samples, we predicted that RcMYB114a functions in the phenylpropanoid pathway. We clarified the relationship between R2R3-MYB gene evolution and function from a new perspective. Our study data may be relevant for elucidating the regulation of floral metabolism in roses at the transcript level. Full article