Integrated transcriptome and metabolome analysis unveils the mechanism of color-transition in Edgeworthia chrysantha tepals.

BACKGROUND: Edgeworthia chrysantha, a deciduous shrub endemic to China, is known for its high ornamental value, extensive cultivation history, and wide-ranging applications. However, theoretical research on this plant is severely lacking. While its flowering process displays striking color transitions from green (S1) to yellow (S2) and then to white (S3), the scientific exploration of this phenomenon is limited, and the underlying regulatory mechanisms are yet to be elucidated. RESULTS: Correlation analysis between phenotypic measurements and pigment content revealed that carotenoids and chlorophyll are the key pigments responsible for the color changes. Metabolomic analysis of carotenoids demonstrated that lutein and ß-carotene were present at higher levels in S1, while S2 exhibited increased diversity and quantity of carotenoids compared to other stages. Notably, antheraxanthin, zeaxanthin, lycopene, and α-cryptoxanthin showed significant increases. In S3, apart from the colorless phytoene, other carotenoid metabolites were significantly reduced to extremely low levels. Transcriptomic data indicated that PSY, Z-ISO, crtZ, ZEP, PDS and ZDS are key genes involved in carotenoid biosynthesis and accumulation, while NCED plays a crucial role in carotenoid degradation. SGR was identified as a key gene contributing to the progressive decline in chlorophyll content. Additionally, three transcription factors potentially regulating carotenoid metabolism were also identified. CONCLUSIONS: This study represents the first systematic investigation, spanning from phenotypic to molecular levels, of the color-changing phenomenon in E. chrysantha. The study elucidates the crucial pigments, metabolites, genes, and transcription factors responsible for flower color changes during the flowering process, thereby providing preliminary understanding of the intrinsic regulatory mechanisms. These findings establish a theoretical foundation for the genetic improvement of flower color in E. chrysantha.

Mining Heat-Resistant Key Genes of Peony Based on Weighted Gene Co-Expression Network Analysis.

The RNA-Seq and gene expression data of mature leaves under high temperature stress of Paeonia suffruticosa 'Hu Hong' were used to explore the key genes of heat tolerance of peony. The weighted gene co-expression network analysis (WGCNA) method was used to construct the network, and the main modules and core genes of co-expression were screened according to the results of gene expression and module function enrichment analysis. According to the correlation of gene expression, the network was divided into 19 modules. By analyzing the expression patterns of each module gene, Blue, Salmon and Yellow were identified as the key modules of peony heat response related functions. GO and KEGG functional enrichment analysis was performed on the genes in the three modules and a network diagram was constructed. Based on this, two key genes PsWRKY53 (TRINITY_DN60998_c1_g2, TRINITY_DN71537_c0_g1) and PsHsfB2b (TRINITY_DN56794_c0_g1) were excavated, which may play a key role in the heat shock response of peony. The three co-expression modules and two key genes were helpful to further elucidate the heat resistance mechanism of P. suffruticosa 'Hu Hong'.

Metabolome and transcriptome integration reveals insights into petals coloration mechanism of three species in Sect. Chrysantha chang.

Background: Sect. Chrysantha Chang, belonging to the Camellia genus, is one of the rare and precious ornamental plants distinguished by a distinctive array of yellow-toned petals. However, the variation mechanisms of petal color in Sect. Chrysantha Chang remains largely unclear. Methods: We conducted an integrated analysis of metabolome and transcriptome to reveal petal coloration mechanism in three species, which have different yellow tones petals, including C. chuongtsoensis (CZ, golden yellow), C. achrysantha (ZD, light yellow), and C. parvipetala (XB, milk white). Results: A total of 356 flavonoid metabolites were detected, and 295 differential metabolites were screened. The contents of 74 differential metabolites showed an upward trend and 19 metabolites showed a downward trend, among which 11 metabolites were annotated to the KEGG pathway database. We speculated that 10 metabolites were closely related to the deepening of the yellowness. Transcriptome analysis indicated that there were 2,948, 14,018 and 13,366 differentially expressed genes (DEGs) between CZ vs. ZD, CZ vs. XB and ZD vs. XB, respectively. Six key structural genes (CcCHI, CcFLS, CcDFR1, CcDFR2, CcDFR3, and CcCYP75B1) and five candidate transcription factors (MYB22, MYB28, MYB17, EREBP9, and EREBP13) were involved in the regulation of flavonoid metabolites. The findings indicate that flavonoid compounds influence the color intensity of yellow-toned petals in Sect. Chrysantha Chang. Our results provide a new perspective on the molecular mechanisms underlying flower color variation and present potential candidate genes for Camellia breeding.

Insight into the Molecular Mechanism of Flower Color Regulation in Rhododendron latoucheae Franch: A Multi-Omics Approach.

Rhododendron latoucheae Franch. (R. latoucheae) is a valuable woody plant known for its high ornamental value. While purple flowers are a distinct and attractive variant phenotype of R. latoucheae, the underlying mechanism regulating its flower color is still poorly understood. To investigate the molecular regulatory mechanism responsible for the variation in flower color, we selected plants with white-pink and purple petals as the object and conducted analyses of metabolites, key genes, and transcription factors associated with flower color. A combined metabolome-transcriptome analysis was performed, and the expression of key genes was subsequently verified through qRT-PCR experiments. The results of our study demonstrated a significant enrichment of differential metabolites in the flavonoid metabolic pathway. Changes in anthocyanin content followed the same trend as the observed flower color variations, specifically showing significant correlations with the contents of malvidin-3-O-glucoside, dihydromyricetin, gallocatechin, and peonidin-3-O-glucoside. Furthermore, we identified three key structural genes (F3GT1, LAR, ANR) and four transcription factors (bHLH130, bHLH41, bHLH123, MYB4) that are potentially associated with the biosynthesis of flavonoid compounds, thereby influencing the appearance of purple flower color in R. latoucheae.

An integrated metabolome and transcriptome analysis of the Hibiscus syriacus L. petals reveal the molecular mechanisms of anthocyanin accumulation.

Hibiscus syriacus L. var. Shigyoku is a new double-flowered bluish-purple variety in China that changes color during flower development from bluish-purple to light purple. There is limited information on the anthocyanin accumulation patterns and associated transcriptome signatures in Shigyoku from D1 (bud) to open flower (D3). Here, we employed a combined transcriptome and metabolome approach to understanding the mechanism of this color change. Our results demonstrate that cyanidins, pelargonidins, delphinidins, petunidins, peonidins, and malvidins were differentially accumulated in Shigyoku petals. The anthocyanin biosynthesis started in D1, was significantly upregulated in D2 (semi-open flower), and reduced in D3. However, malvidins, pelargonidins, and peonidins could be associated with the bluish-purple coloration on D2. Their reduced accumulation in D3 imparted the light purple coloration to Shigyoku petals on D3. Significant contributions in the color change could be associated with the expression changes in anthocyanin biosynthesis genes i.e., LARs, ANSs, DFRs, UGT79B1, C3'Hs, 3ATs, and BZ1s. The UFGTs were associated with the higher accumulation of glycosylated anthocyanins in D2 and D3. Furthermore, the changes in the expressions of the MYB and bHLH transcription factors were consistent with the anthocyanin accumulation. Finally, we discussed the possible roles of Jasmonic acid, auxin, and gibberellic acid signaling in regulating the MBW complex. Taken together, we conclude that H. syriacus petal coloration is associated with anthocyanin biosynthesis genes, the MBW complex, and phytohormone signaling.

[Physiological response of Xinjiang wild walnut germplasm to low temperature stress]. / æ–°ç–†é‡Žæ ¸æ¡ƒç§è´¨å¯¹ä½Žæ¸©èƒè¿«çš„ç”Ÿç†å“åº”.

We examined the physiological response of 1-year-old branches of 37 Xinjiang wild walnut germplasm resources in Gongliu wild walnut forest under cold temperatures (-20 ℃ and 4 ℃) for 12 hours, compared the responses with that of Juglans mandshurica. The relative conductivity (REC), free proline (PRO), soluble sugar (SS), malondialdehyde (MDA) content and peroxidase (POD) activity were measured in an artificial climate chamber by simulating spring low temperature. Subordinate function and principal component analysis were used to evaluate the physiological response of walnut germplasm to low temperature. The results showed that the REC, PRO, SS, MDA content and POD activity of Xinjiang wild walnut were increased. By evaluating the relationship between low temperature resistance and habitat, we found that cold tolerance level was middle valley > east valley > west valley > general valley. Xinjiang wild walnut showed stronger cold tolerance than J. mandshurica. Seven germplasm with cold resistance were selected from the total 37 wild walnut germplasm in Xinjiang, which provided a reference for improving walnut varieties and their responses to sudden weather change in late spring and other growing stages.

Overexpression of Saussurea involucrata dehydrin gene SiDHN promotes cold and drought tolerance in transgenic tomato plants.

Dehydrins are late embryogenesis abundant proteins that help regulate abiotic stress responses in plants. Overexpression of the Saussurea involucrata dehydrin gene SiDHN has previously been shown to improve water-use efficiency and enhance cold and drought tolerance of transgenic tobacco. To understand the mechanism by which SiDHN exerts its protective function, we transformed the SiDHN gene into tomato plants (Solanum lycopersicum L.) and assessed their response to abiotic stress. We observed that in response to stresses, the SiDHN transgenic tomato plants had increased contents of chlorophyll a and b, carotenoid and relative water content compared with wild-type plants. They also had higher maximal photochemical efficiency of photosystem II and accumulated more proline and soluble sugar. Compared to those wild-type plants, malondialdehyde content and relative electron leakage in transgenic plants were not significantly increased, and H2O2 and O2- contents in transgenic tomato plants were significantly decreased. We further observed that the production of stress-related antioxidant enzymes, including superoxide dismutase, ascorbate peroxidase, peroxidase, and catalase, as well as pyrroline-5-carboxylate synthetase and lipid transfer protein 1, were up-regulated in the transgenic plants under cold and drought stress. Based on these observations, we conclude that overexpression of SiDHN gene can promote cold and drought tolerance of transgenic tomato plants by inhibiting cell membrane damage, protecting chloroplasts, and enhancing the reactive oxygen species scavenging capacity. The finding can be beneficial for the application of SiDHN gene in improving crop tolerance to abiotic stress and oxidative damage.