Functional Differentiation of Duplicated Flavonoid 3-O-Glycosyltransferases in the Flavonol and Anthocyanin Biosynthesis of Freesia hybrida

Flavonoids as Insecticides in Crop Protection-A Review of Current Research and Future Prospects

Pesticide overuse in agricultural systems has resulted in the development of pest resistance, the impoverishment of soil microbiota, water pollution, and several human health issues. Nonetheless, farmers still depend heavily on these agrochemicals for economically viable production, given the high frequency at which crops are affected by pests. Phytopathogenic insects are considered the most destructive pests on crops. Botanical pesticides have gained attention as potential biopesticides and complements to traditional pesticides, owing to their biodegradability and low toxicity. Plant-based extracts are abundant in a wide variety of bioactive compounds, such as flavonoids, a class of polyphenols that have been extensively studied for this purpose because of their involvement in plant defense responses. The present review offers a comprehensive review of current research on the potential of flavonoids as insecticides for crop protection, addressing the modes and possible mechanisms of action underlying their bioactivity. The structure-activity relationship is also discussed. It also addresses challenges associated with their application in pest and disease management and suggests alternatives to overcome these issues.

Metabolomics provide a novel interpretation of the changes in flavonoids during sea buckthorn (Hippophae rhamnoides L.) drying

Flavonoids are major nutrients in sea buckthorn berries. However, the effects of drying methods on flavonoids in sea buckthorn berries are unclear. In this study, ultra-performance liquid chromatography and metabolomics were adopted to analyse the effects of hot air drying (HAD) and infrared drying (IRD) on flavonoid compounds and antioxidant capacity in sea buckthorn berries. In total, 97 metabolites belonging to 12 classes were identified, including 26 flavones, 23 flavonols, and 11 flavanones. Additionally, 32 differential metabolites were identified among groups. Isorhamnetin and quercetin contents increased in response to HAD and IRD, while (-)-epigallocatechin and (-)-gallocatechin contents decreased. Differential metabolism of flavonoid compounds occurred mainly via the flavonoid biosynthesis and secondary metabolite biosynthesis pathways. Flavonoid compound degradation might be associated with antioxidant activity during drying. This study elucidated the effect of drying on nutritional components of sea buckthorn berries and may guide the improvement of quality during food processing.

BcMYB111 Responds to BcCBF2 and Induces Flavonol Biosynthesis to Enhance Tolerance under Cold Stress in Non-Heading Chinese Cabbage

Flavonols have been shown to respond to a variety of abiotic stresses in plants, including cold stress. Higher total flavonoid content was found in non-heading Chinese cabbage (NHCC, Brassica campestris (syn. Brassica rapa) ssp. chinensis) after cold stress. A non-targeted metabolome analysis showed a significant increase in flavonol content, including that of quercetin and kaempferol. Here, we found that an R2R3-MYB transcription factor, BcMYB111, may play a role in this process. BcMYB111 was up-regulated in response to cold treatment, with an accompanying accumulation of flavonols. Then, it was found that BcMYB111 could regulate the synthesis of flavonols by directly binding to the promoters of BcF3H and BcFLS1. In the transgenic hairy roots of NHCC or stable transgenic Arabidopsis, overexpression of BcMYB111 increased flavonol synthesis and accumulation, while these were reduced in virus-induced gene silencing lines in NHCC. After cold stress, the higher proline content and lower malondialdehyde (MDA) content showed that there was less damage in transgenic Arabidopsis than in the wild-type (WT). The BcMYB111 transgenic lines performed better in terms of antioxidant capacity because of their lower H₂O₂ content and higher superoxide dismutase (SOD) and peroxidase (POD) enzyme activities. In addition, a key cold signaling gene, BcCBF2, could specifically bind to the DRE element and activate the expression of BcMYB111 in vitro and in vivo. The results suggested that BcMYB111 played a positive role in enhancing the flavonol synthesis and cold tolerance of NHCC. Taken together, these findings reveal that cold stress induces the accumulation of flavonols to increase tolerance via the pathway of BcCBF2-BcMYB111-BcF3H/BcFLS1 in NHCC.

VrMYB90 Functions Synergistically with VrbHLHA and VrMYB3 to Regulate Anthocyanin Biosynthesis in Mung Bean

Mung bean is an important grain-legume crop and its sprout is an economical and nutrient vegetable for the public, but the genetic regulation of anthocyanin production, which is an antioxidant in mung bean, remains elusive. In our study, we characterized a subgroup (SG) 6 R2R3-MYB anthocyanin activator VrMYB90 and a SG 4 R2R3-MYB anthocyanin repressor VrMYB3, which synergistically function in regulating anthocyanin synthesis with VrbHLHA transcription factor. The overexpressed VrMYB90 protein activates the expression of VrMYB3 and VrbHLHA in mung bean hair roots, and also promotes VrDFR and VrANS transcript levels by directly binding to the corresponding promoters at specific motifs (CAACTG and CCGTTG). VrMYB90 interacts with VrbHLHA to enhance its regulatory activities on VrDFR and VrANS. Furthermore, the interaction between VrMYB3 with VrMYB90 and VrbHLHA could result in the restriction of anthocyanin synthesis to prevent excessive anthocyanin accumulation. Our results demonstrate that the VrMYB90 protein, in conjunction with VrMYB3 and VrbHLHA, forms a key regulatory module to fine-tune anthocyanin synthesis in mung bean.

Anthocyanins Profiling Analysis and RNA-Seq Revealed the Dominating Pigments and Coloring Mechanism in Cyclamen Flowers

Pigments in cyclamen (Cyclamen purpurascens) endows flowers with great ornamental and medicinal values. However, little is known about the biosynthetic pathways of pigments, especially anthocyanins, in cyclamen flowers. Herein, anthocyanins profiling and RNA-Seq were used to decipher the molecular events using cyclamen genotypes of red (HXK) or white (BXK) flowers. We found that red cyclamen petals are rich in cyanidin-3-O-rutinoside, cyanidin-3-O-glucoside, delphinidin-3-O-glucoside, malvidin-3-O-glucoside, peonidin-3-O-rutinoside, quercetin-3-O-glucoside, and ruti. In addition, our transcriptomics data revealed 3589 up-regulated genes and 2788 down-regulated genes comparing the BXK to HXK. Our rich dataset also identified eight putative key genes for anthocyanin synthesis, including four chalcone synthase (CHS, g13809_i0, g12097_i0, g18851_i0, g36714_i0), one chalcone isomerase (CHI, g26337_i0), two flavonoid 3-hydroxylase (F3'H, g14710_i0 and g15005_i0), and one anthocyanidin synthase (ANS, g18981_i0). Importantly, we found a 2.5 order of magnitude higher expression of anthocyanin 3-O-glucosyltransferase (g8206_i0), which encodes a key gene in glycosylation of anthocyanins, in HXK compared to BXK. Taken together, our multiomics approach demonstrated massive changes in gene regulatory networks and anthocyanin metabolism in controlling cyclamen flower color.

Ph5GT silencing alters flower color and flavonoids metabolome profile in petunia

Anthocyanins are important pigments in plants and glycosylation plays an important role in the stability of anthocyanins. Anthocyanin 5-O-glucosyltransferase (5GT) can glycosylate anthocyanin at the 5-O-position. Till now, the enzymatic activity characteristics of 5GT had been studied in vitro in a variety of plants. However, the subcellular localization of 5GT protein still remained unclear, and little genetic evidence on the roles of 5GT in plants has been reported. The full-length Ph5GT gene from petunia (Petunia hybrida) was isolated in this study. Green fluorescent fusion protein assays revealed that Ph5GT protein was localized to the cytoplasm. Ph5GT was found to be highly expressed in flowers, with highest levels of expression occurring during the coloring stage of flower development. Furthermore, Ph5GT silencing led to the change in flower color from purple to light purple and a significant reduction in total anthocyanin content. The metabolome analysis revealed that the content of malvidins and petunidins modified by glycosylation at the 5-O-position was significantly reduced, while the content of their precursor without glycosylation was significantly increased, implying that Ph5GT could glycosylate malvidin and petunidin derivatives and that the substrate types of Ph5GT were expanded in comparison to previous studies.

Comparative Transcriptome and Pigment Analyses Reveal Changes in Gene Expression Associated with Flavonol Metabolism in Yellow Camellia

The accumulation of various pigments leads to the formation of different flower colors in plants. However, the regulation mechanism of yellow flower formation and flower color differences between Camellia nitidssima C.W.Chi (CN) and its hybrids C. ‘Zhenghuangqi’ (ZHQ), C. ‘Huangxuanlv’ (HXL), and C. ‘Xinshiji’ (XSJ), remains largely unknown. Here, we showed that the content of two flavonols, quercetin-7-O-glucoside (Qu7G) and quercetin-3-O-glucoside (Qu3G), was positively correlated with the yellow degree of petals in CN and its three hybrids. Additionally, we performed a comparative transcriptomic analysis of petals of the four yellow camellia plants, which revealed 322 common upregulated and 866 common downregulated DEGs (differentially expressed genes) in the CN vs. ZHQ, CN vs. HXL, and CN vs. XSJ comparison groups. Their regulatory pathway analysis showed that flavonol biosynthesis genes (FLSs and GTs) and transcriptional regulatory genes MYBs were all expressed higher in CN than its three hybrids, which corresponded to differences in the flavonol content among the four yellow camellias. Further, two ethylene synthesis genes (ACSs, ACO) and three ethylene signaling genes (EIN2s, EIN3, ERFs) were all upregulated in the yellow petals of CN. In conclusion, the expression of flavonol-related genes and flavonols (Qu7G and Qu3G) accumulation could play a key role in the formation of yellow flowers in camellia, and the ethylene pathway might be involved in the regulation of yellow flower formation of camellias. This work describes the possible regulatory pathway of yellow camellia, thereby laying a foundation for future verification of genes linked to flower coloring and the breeding of yellow camellia.

Identification of microRNAs and their target genes related to the accumulation of anthocyanin in purple potato tubers (Solanum tuberosum)

MicroRNAs (miRNAs) are types of endogenous non-coding small RNAs found in eukaryotes that are 18-25 nucleotides long. miRNAs are considered to be key regulatory factors of the expression of target mRNA. The roles of miRNAs involved in the regulation of anthocyanin accumulation in pigmented potatoes have not been systematically reported. In this study, the differentially expressed miRNAs and their target genes involved in the accumulation of anthocyanin during different developmental stages in purple potato (Solanum tuberosum L.) were identified using small RNA (sRNA) and degradome sequencing. A total of 275 differentially expressed miRNAs were identified in the sRNA libraries. A total of 69,387,200 raw reads were obtained from three degradome libraries. The anthocyanin responsive miRNA-mRNA modules were analyzed, and 37 miRNAs and 23 target genes were obtained. Different miRNAs regulate the key enzymes of anthocyanin synthesis in purple potato. The structural genes included phenylalanine ammonia lyase, chalcone isomerase, flavanone 3-hydroxylase, and anthocyanidin 3-O-glucosyltransferase. The regulatory genes included WD40, MYB, and SPL9. stu-miR172e-5p_L-1R-1, stu-miR828a, stu-miR29b-4-5p, stu-miR8019-5p_L-4R-3, stu-miR396b-5p, stu-miR5303f_L-7R + 2, stu-miR7997a_L-3, stu-miR7997b_L-3, stu-miR7997c_L + 3R-5_2ss2TA3AG, stu-miR156f-5p_L + 1, stu-miR156a, stu-miR156a_R-1, stu-miR156e, stu-miR858, stu-miR5021, stu-miR828 and their target genes were validated by qRT-PCR. They play important roles in the coloration and accumulation of purple potatoes. These results provide new insights into the biosynthesis of anthocyanins in pigmented potatoes.

The Flavonoid Biosynthesis Network in Plants

Flavonoids are an important class of secondary metabolites widely found in plants, contributing to plant growth and development and having prominent applications in food and medicine. The biosynthesis of flavonoids has long been the focus of intense research in plant biology. Flavonoids are derived from the phenylpropanoid metabolic pathway, and have a basic structure that comprises a C15 benzene ring structure of C6-C3-C6. Over recent decades, a considerable number of studies have been directed at elucidating the mechanisms involved in flavonoid biosynthesis in plants. In this review, we systematically summarize the flavonoid biosynthetic pathway. We further assemble an exhaustive map of flavonoid biosynthesis in plants comprising eight branches (stilbene, aurone, flavone, isoflavone, flavonol, phlobaphene, proanthocyanidin, and anthocyanin biosynthesis) and four important intermediate metabolites (chalcone, flavanone, dihydroflavonol, and leucoanthocyanidin). This review affords a comprehensive overview of the current knowledge regarding flavonoid biosynthesis, and provides the theoretical basis for further elucidating the pathways involved in the biosynthesis of flavonoids, which will aid in better understanding their functions and potential uses.

Composition of Flavonoids in the Petals of Freesia and Prediction of Four Novel Transcription Factors Involving in Freesia Flavonoid Pathway

Freesia hybrida is rich in flower colors with beautiful flower shapes and pleasant aroma. Flavonoids are vital to the color formation of its flowers. In this study, five Freesia cultivars with different flower colors were used to study on the level of accumulation of their flavonoids and expression of flavonoid-related genes and further explore new novel transcription factor (TF). Ultra-high-performance liquid chromatography and VION ion mobility quadrupole time-of-flight mass spectrometer (UPLC-Q-TOF-MS) were used to determine the flavonoids. Combined with transcriptome sequencing technology, the molecular mechanism of the flavonoid metabolism difference in Freesia was revealed. A total of 10 anthoxanthin components and 12 anthocyanin components were detected using UPLC-Q-TOF-MS. All six common anthocyanin aglycones in high plants, including cyanidin, delphinidin, petunidin, peonidin, malvidin, and pelargonidin, were detected in Freesia at first time in this study. In orange, yellow, and white cultivars, anthoxanthins gradually decreased with the opening of the petals, while in red and purple cultivars, anthoxanthins first increased and then decreased. No anthocyanin was detected in yellow and white cultivars, while anthocyanins increased with the opening of the petals and reached their maximum at the flowering stage (S3) in other three cultivars. The correlation analysis revealed that the color of Freesia petals was closely related to the composition and content of anthoxanthins and anthocyanins. Petals of five cultivars at S3 were then selected for transcriptome sequencing by using the Illumina Hiseq 4000 platform, and a total of 100,539 unigenes were obtained. There were totally 5,162 differentially expressed genes (DEGs) when the four colored cultivars were compared with the white cultivar at S3. Comparing all DEGs with gene ontology (GO), KEGG, and Pfam databases, it was found that the genes involved in the flavonoid biosynthesis pathway were significantly different. In addition, AP2, WRKY, and bHLH TF families ranked the top three among all differently expressed TFs in all DEGs. Quantitative real-time PCR (qRT-PCR) technology was used to analyze the expression patterns of the structural genes of flavonoid biosynthesis pathway in Freesia. The results showed that metabolic process was affected significantly by structural genes in this pathway, such as CHS1, CHI2, DFR1, ANS1, 3GT1, and FLS1. Cluster analysis was performed by using all annotated WRKY and AP2 TFs and the above structural genes based on their relatively expression. Four novel candidate TFs of WRKY and AP2 family were screened. Their spatiotemporal expression patterns revealed that these four novel TFs may participate in the regulation of the flavonoid biosynthesis, thus controlling its color formation in Freesia petals.

Antioxidant and antibacterial study of 10 flavonoids revealed rutin as a potential antibiofilm agent in Klebsiella pneumoniae strains isolated from hospitalized patients

The emergence of multidrug resistance (MDR) and extensive drug resistance (XDR) in Klebsiella pneumoniae strains has posed great threats to conventional antibiotics. Previous studies have shown that plant-derived flavonoids have inhibitory functions against pathogens. However, in K. pneumoniae, the antibacterial activity of different flavonoids against growth and biofilm formation remains a mystery. The aim of the present study was to evaluate the antioxidant abilities of different flavonoids, to screen active ingredients and to identify their inhibitory effects on K. pneumoniae growth and biofilm formation. In total, 10 flavonoids representing 4 major categories were screened and used in this study. The antioxidant capacity of each flavonoid was evaluated through a DPPH (2,2-diphenyl-1-picrylhydrazyl) assay. Rutin showed the highest level of free radical scavenging capacity, followed by kaempferol, luteolin, quercetin, apigenin, hesperidin, sinensetin, naringenin, naringin and 3,5,6,7,8,3',4'-heptamethoxyflavone. The inhibitory effects of rutin and naringin on bacterial growth were also compared. The lowest MICs of rutin were found against K. pneumoniae ATCC700603 (1024 μg/mL) and E. coli ATCC25922 (512 μg/mL). However, the MBICs were not found. Rutin showed strong inhibitory ability against both the growth curve and biofilm production. The expression profiles of 15 biofilm-related genes were analyzed in biofilm cells both with and without rutin treatment. The luxS gene and wabG gene were downregulated significantly by rutin treatment. Correlation analysis showed that mrkA gene expression was positively correlated with biofilm biomass accumulation. Our study indicated that biofilm production is correlated with the expression of several genes rather than one. MrkA gene expression was positively correlated with biofilm biomass accumulation. Our study screened rutin as a potential agent to inhibit K. pneumoniae biofilm formation.

Characterization of 5-O-glucosyltransferase involved in anthocyanin biosynthesis in Cyclamen purpurascens

Wild cyclamen (Cyclamen purpurascens) is considered as a precious breeding material for the development of new cultivars. Malvidin 3,5-diglucoside is the main anthocyanin in the petals of C. purpurascens, whereas the F1 progeny of the C. persicum × C. purpurascens cultivars cross contains 3,5-diglucoside-type anthocyanins as the main pigment. The anthocyanin 5-O-glucosyltransferase (A5GT) enzyme is responsible for the glycosylation of the A ring of anthocyanin at the 5-O-position, which implies that the expression of A5GT is dominant in the petals of C. purpurascens × C. persicum cultivars. Here, we isolated the complete open reading frame of the A5GT gene from C. purpurascens (Cpur5GT). Results of qRT-PCR revealed that Cpur5GT shows tissue-specific expression, with strong expression in fully opened petals and weak expression in young petals. In vitro enzyme assay showed that when uridine diphosphate glucose was used as the sugar donor, recombinant Cpur5GT could catalyze the glycosylation of 3-glucoside-type anthocyanidins at the 5-O-position, but when uridine diphosphate galactose was served as glycosyl donor, the reaction could not be performed. These results demonstrate that Cpur5GT exhibits valid anthocyanin glucosylation activity and could be used to analyze the mechanism of A5GT-mediated flower coloration in cyclamen in future studies.

MYB transcription factors GmMYBA2 and GmMYBR function in a feedback loop to control pigmentation of seed coat in soybean

Soybean has undergone extensive selection pressures for seed nutrient composition and seed color during domestication, but the major genetic loci controlling seed coat color have not been completely understood, and the transcriptional regulation relationship among the loci remains elusive. Here, two major regulators, GmMYBA2 and GmMYBR, were functionally characterized as an anthocyanin activator and repressor, respectively. Ectopic expression of GmMYBA2 in soybean hairy roots conferred the enhanced accumulation of delphinidin and cyanidin types of anthocyanins in W1t and w1T backgrounds, respectively, through activating anthocyanin biosynthetic genes in the reported loci. The seed coat pigmentation of GmMYBA2-overexpressing transgenic plants in the W1 background mimicked the imperfect black phenotype (W1/w1, i, R, t), suggesting that GmMYBA2 was responsible for the R locus. Molecular and biochemical analysis showed that GmMYBA2 interacted with GmTT8a to directly activate anthocyanin biosynthetic genes. GmMYBA2 and GmMYBR might form a feedback loop to fine-tune seed coat coloration, which was confirmed in transgenic soybeans. Both GmTT8a and GmMYBR that were activated by GmMYBA2 in turn enhanced and obstructed the formation of the GmMYBA2-GmTT8a module, respectively. The results revealed the sophisticated regulatory network underlying the soybean seed coat pigmentation loci and shed light on the understanding of the seed coat coloration and other seed inclusions.

The spatio-temporal biosynthesis of floral flavonols is controlled by differential phylogenetic MYB regulators in Freesia hybrida

Floral flavonols play specific pivotal roles in pollinator attraction, pollen germination and fertility, in addition to other functions in vegetative organs. For many plants, the process of flavonol biosynthesis in late flower development stages and in mature flower tissues is poorly understood, in contrast to early flower development stages. It is thought that this process may be regulated independently of subgroup 7 R2R3 MYB (SG7 MYB) transcription factors. In this study, two FLS genes were shown to be expressed synchronously with the flower development-specific and tissue-specific biosynthesis of flavonols in Freesia hybrida. FhFLS1 contributed to flavonol biosynthesis in early flower buds, toruses and calyxes, and was regulated by four well-known SG7 MYB proteins, designated as FhMYBFs, with at least partial regulatory redundancy. FhFLS2 accounted for flavonols in late developed flowers and in the petals, stamens and pistils, and was targeted directly by non SG7 MYB protein FhMYB21L2. In parallel, AtMYB21 and AtMYB24 also activated AtFLS1, a gene highly expressed in Arabidopsis anthers and pollen, indicating the conserved regulatory roles of MYB21 against FLS genes in these two evolutionarily divergent angiosperm plants. Our results reveal a novel regulatory and synthetic mechanism underlying flavonol biosynthesis in floral organs and tissues which may be exploited to investigate supplementary roles of flavonols in flowers.

MYB repressors and MBW activation complex collaborate to fine-tune flower coloration in Freesia hybrida

Floral anthocyanin has multiple ecological and economic values, its biosynthesis largely depends on the conserved MYB-bHLH-WD40 (MBW) activation complex and MYB repressors hierarchically with the MBW complex. In contrast to eudicots, the MBW regulatory network model has not been addressed in monocots because of the lack of a suitable system, as grass plants exhibit monotonous floral pigmentation patterns. Presently, the MBW regulatory network was investigated in a non-grass monocot plant, Freesia hybrida. FhMYB27 and FhMYBx with different functional manners were confirmed to be anthocyanin related R2R3 and R3 MYB repressors, respectively. Particularly, FhMYBx could obstruct the formation of positive MBW complex by titrating bHLH proteins, whereas FhMYB27 mainly defected the activator complex into suppressor via its repression domains in C-terminus. Furthermore, the hierarchical and feedback regulatory loop was verified, indicating the synergistic and sophisticated regulatory network underlying Freesia anthocyanin biosynthesis was quite similar to that reported in eudicot plants.

Yueqing Li, Xiaotong Shan, et al. study the MYB-bHLH-WD40 (MBW) regulatory network in a non-grass monocot plant, Freesia hybrida. They report two anthocyanin related MYB repressors FhMYB27 and FhMYBx and verified their involvement in a functional feedback loop with MBW to regulate anthocyanin biosynthesis.

MYB21 interacts with MYC2 to control the expression of terpene synthase genes in flowers of Freesia hybrida and Arabidopsis thaliana

Previously, linalool was found to be the most abundant component among the cocktail of volatiles released from flowers of Freesia hybrida. Linalool formation is catalysed by monoterpene synthase TPS1. However, the regulatory network developmentally modulating the expression of the TPS1 gene in Freesia hybrida remains unexplored. In this study, three regulatory genes, FhMYB21L1, FhMYB21L2, and FhMYC2, were screened from 52 candidates. Two MYB transcription factor genes were synchronously expressed with FhTPS1 and could activate its expression significantly when overexpressed, and the binding of FhMYB21L2 to the MYBCORE sites in the FhTPS1 promoter was further confirmed, indicating a direct role in activation. FhMYC2 showed an inverse expression pattern compared with FhTPS1; its expression led to a decreased binding of FhMYB21 to the FhTPS1 promoter to reduce its activation capacity when co-expressed, suggesting a role for an MYB-bHLH complex in the regulation of the FhTPS1 gene. In Arabidopsis, both MYB21 and MYC2 regulators were shown to activate the expression of sesquiterpene synthase genes, and the regulatory roles of AtMYB21 and AtMYC2 in the expression of the linalool synthase gene were also confirmed, implying conserved functions of the MYB-bHLH complex in these two evolutionarily divergent plants. Moreover, the expression ratio between MYB21 and MYC2 orthologues might be a determinant factor in floral linalool emission.

The Conserved and Particular Roles of the R2R3-MYB Regulator FhPAP1 from Freesia hybrida in Flower Anthocyanin Biosynthesis

Anthocyanin biosynthesis is mainly controlled by MYB-bHLH-WD40 (MBW) complexes that modulate the expression of anthocyanin biosynthetic genes (ABGs). The MYB regulators involved in anthocyanin biosynthesis arose early during plant evolution and thus might function divergently in different evolutionary lineages. Although the anthocyanin-promoting R2R3-MYB regulators in eudicots have been comprehensively explored, little consensus has been reached about functional discrepancies versus conservation among MYB regulators from different plant lineages. Here, we integrated transcriptome analysis, gene expression profiles, gain-of-function experiments and transient protoplast transfection assays to functionally characterize the monocot Freesia hybrida anthocyanin MYB regulator gene FhPAP1, which showed correlations with late ABGs. FhPAP1 could activate ABGs as well as TT8-clade genes FhTT8L, AtTT8 and NtAN1 when overexpressed in Freesia, Arabidopsis and tobacco, respectively. Consistently, FhPAP1 could interact with FhTT8L and FhTTG1 to form the conserved MBW complex and shared similar target genes with its orthologs from Arabidopsis. Most prominently, FhPAP1 displayed higher transactivation capacity than its homologs in Arabidopsis and tobacco, which was instantiated in its powerful regulation on ABGs. Moreover, we found that FhPAP1 might be the selected gene during the domestication and rapid evolution of the wild Freesia species to generate intensive flower pigmentation. These results showed that while the MBW complex was highly evolutionarily conserved between tested monocot and core eudicot plants, participating MYB regulators showed functional differences in transactivation capacity according to their activation domain and played important roles in the flower coloration domestication and evolution of angiosperms.

Red orange and lemon extract prevents the renal toxicity induced by ochratoxin A in rats

In this work, we investigated the effects of red orange and lemon extract (RLE) on ochratoxin A (OTA)-induced nephrotoxicity. In particular, we analyzed the change in renal function and oxidative stress in Sprague-Dawley rats treated with OTA (0.5 mg/kg body weight, b.w.) and with RLE (90 mg/kg b.w.) by oral administration. After OTA treatment, we found alterations of biochemical and oxidative stress parameters in the kidney, related to a severe decrease of glomerular filtration rate. The RLE treatment normalized the activity of antioxidant enzymes and prevented the glomerular hyperfiltration. Histopathological examinations revealed glomerular damages and kidney cortex fibrosis in OTA-rats, while we observed less severe fibrosis in OTA plus RLE group. Then, we demonstrated that oxidative stress could be the cause of OTA renal injury and that RLE reduces this effect.