Identification of MYB Transcription Factors Involving in Fruit Quality Regulation of Fragaria × ananassa Duch

Genome-wide identification and analysis of anthocyanin synthesis-related R2R3-MYB genes in Fragaria pentaphylla

BACKGROUND

MYB transcription factors regulate anthocyanin biosynthesis across numerous plant species. However, comprehensive genome-wide investigations regarding the R2R3-MYB gene family and its involvement in regulating anthocyanin biosynthesis in the red and white fruit color morphs of Fragaria pentaphylla remain scarce.

RESULTS

A total of 101 FpR2R3-MYB genes were identified from the F. pentaphylla genome and were divided into 34 subgroups based on phylogenetic analysis. Gene structure (exon/intron) and protein motifs were particularly conserved among the FpR2R3-MYB genes, especially members within the same subgroup. The FpR2R3-MYB genes were distributed over seven F. pentaphylla chromosomes. Analysis of gene duplication events revealed five pairs of tandem duplication genes and 16 pairs of segmental duplication genes, suggesting that segmental duplications are the major pattern for expansion of the FpR2R3-MYB gene family expansion in F. pentaphylla. Cis-regulatory elements of the FpR2R3-MYB promoters were involved in cellular development, phytohormones, environmental stress and photoresponse. Based on the analysis of the FpR2R3-MYB gene family and transcriptome sequencing (RNA-seq) data, FpMYB9 was identified as a key transcription factor involved in the regulation of anthocyanin synthesis in F. pentaphylla fruits. The expression of FpMYB9 increases significantly during the ripening stage of red fruits, as confirmed by reverse transcription quantitative real-time PCR. In addition, subcellular localization experiments further confirmed the nuclear presence of FpMYB9, supporting its role as a transcription factor involved in anthocyanin biosynthesis.

CONCLUSION

Our results showed that the FpR2R3-MYB genes are highly conserved and play important roles in the anthocyanin biosynthesis in F. pentaphylla fruits. Our results also provide a compelling basis for further understanding of the regulatory mechanism underlying the role of FpMYB9 in anthocyanin formation in F. pentaphylla fruits.

Genome-Wide Analysis of Cotton MYB Transcription Factors and the Functional Validation of GhMYB in Response to Drought Stress

MYB transcription factors play important roles during abiotic stress responses in plants. However, little is known about the accurate systematic analysis of MYB genes in the four cotton species, Gossypium hirsutum, G. barbadense, G. arboreum and G. raimondii. Herein, we performed phylogenetic analysis and showed that cotton MYBs and Arabidopsis MYBs were clustered in the same subfamilies for each species. The identified cotton MYBs were distributed unevenly on chromosomes in various densities for each species, wherein genome-wide tandem and segment duplications were the main driving force of MYB family expansion. Synteny analysis suggested that the abundant collinearity pairs of MYBs were identified between G. hirsutum and the other three species, and that they might have undergone strong purification selection. Characteristics of conserved motifs, along with their consensus sequence, promoter cis elements and gene structure, revealed that MYB proteins might be highly conserved in the same subgroups for each species. Subsequent analysis of differentially expressed genes and expression patterns indicated that most GhMYBs might be involved in response to drought (especially) and salt stress, which was supported by the expression levels of nine GhMYBs using real-time quantitative PCR. Finally, we performed a workflow that combined virus-induced gene silencing and the heterologous transformation of Arabidopsis, which confirmed the positive roles of GhMYBs under drought conditions, as validated by determining the drought-tolerant phenotypes, damage index and/or water loss rate. Collectively, our findings not only expand our understanding of the relationships between evolution and function of MYB genes, but they also provide candidate genes for cotton breeding.

The Chinese herbal medicine Dai-Zong-Fang promotes browning of white adipocytes in vivo and in vitro by activating PKA pathway to ameliorate obesity

Introduction: The global prevalence of obesity is rising rapidly. Conversion of white adipose tissue (WAT) into beige adipose tissue with heat-consuming characteristics, i.e., WAT browning, effectively inhibits obesity. Dai-Zong-Fang (DZF), a traditional Chinese medicine formula, has long been used to treat metabolic syndrome and obesity. This study aimed to explore the pharmacological mechanism of DZF against obesity. Methods: In vivo, C57BL/6J mice were fed high-fat diets to establish the diet-induced obese (DIO) model. DZF (0.40 g/kg and 0.20 g/kg) and metformin (0.15 g/kg, positive control drug) were used as intervention drugs for six weeks, respectively. The effects of DZF on body size, blood glucose and lipid level, structure and morphology of adipocytes and browning of inguinal WAT (iWAT) in DIO mice were observed. In vitro, mature 3T3-L1 adipocytes were used as the model. Concentrations of DZF (0.8 mg/mL and 0.4 mg/mL) were selected according to the Cell Counting Kit-8 (CCK8). After 2d intervention, lipid droplet morphology was observed by BODIPY493/503 staining, and mitochondria number was observed by mito-tracker Green staining. H-89 dihydrochloride, a PKA inhibitor, was used to observe the change in browning markers' expression. The expression levels of browning markers UCP1 and PGC-1α and key molecules of PKA pathway were detected in vivo and in vitro. Results: In vivo, compared with vehicle control group, 0.40 g/kg DZF significantly reduced obesity in DIO mice from body weight, abdomen circumference, Lee's index, and WAT/body weight (p < 0.01 or p < 0.001). 0.40 g/kg DZF also significantly reduced fasting blood glucose (FBG), serum triglycerides (TG), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) (p < 0.01 or p < 0.001). The iWAT's morphology and mitochondria were browning after DZF intervention. In HE-staining, the lipid droplets became smaller, and the number of mitochondria increased. The mitochondrial structure was remodeled under the electron microscope. The expression of UCP1, PGC-1α and PKA was elevated in iWAT detected by RT-qPCR (p < 0.05 or p < 0.001). In vitro, compared with the control group, 0.8 mg/mL DZF intervention significantly increased the number of mitochondria and expression of UCP1, PGC-1α, PKA, and pCREB (p < 0.05 or p < 0.01). In contrast, UCP1 and PGC-1α expression were significantly reversed after adding PKA inhibitor H-89 dihydrochloride. Conclusion: DZF can promote UCP1 expression by activating the PKA pathway, thereby promoting browning of WAT, attenuating obesity, and reducing obesity-related glucose and lipid metabolism abnormalities, indicating that DZF has the potential to be selected as an anti-obesity drug to benefit obese patients.