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Xibei tree peony is a distinctive cultivar group that features the red-purple blotches in petals. Interestingly, the pigmentation of blotches and non-blotches is largely independent of one another. The underlying molecular mechanism had attracted lots of attention from investigators, but was still uncertain. Our present work demonstrated the factors that closely related to the blotch formation of Paeonia rockii ‘Shu Sheng Peng Mo’. The non-blotch pigmentation is prevented by the silence of anthocyanin structural genes, among which PrF3H, PrDFR, and PrANS are the three major genes. We characterized two R2R3-MYBs as the key transcription factors that control the anthocyanin early and late biosynthetic pathways, respectively. PrMYBa1, which belongs to MYB SG7 (subgroup 7) was found to activates the EBG (early biosynthetic gene) PrF3H by interacting with SG5 member PrMYBa2 to form a ‘MM’ complex. The SG6 member PrMYBa3 interacts with two SG5 (IIIf) bHLHs to synergistically activate the LBGs (late biosynthetic genes) PrDFR and PrANS, which is essential for anthocyanin accumulation in blotch of petals. The comparison of methylation levels of PrANS and PrF3H promoters between blotch and non-blotch indicated a correlation between hypermethylation and gene silencing. The methylation dynamics of PrANS promoter during flower development revealed a potential demethylating reaction in the early stage, and this reaction may have contributed to the particular expression of PrANS solely in blotch area. We suggest that the cooperation of transcriptional activation and DNA methylation of structural gene promoters may be strongly correlated with the formation of petal blotch.

SUMMARYDevelopment of photosynthetically competent seedlings requires both light and retrograde biogenic signaling pathways. The transcription factor GLK1 functions at the interface between these pathways, and receives input from the biogenic-signaling integrator GUN1. BBX14 was previously identified, together with GLK1, in a core module that mediates the response to high light levels and biogenic signaling. To gain insight into the function of BBX14, we generatedBBX14overexpressors and CRISPR/Cas-mediatedbbx14mutant plants, conducted high-light, RT-qPCR and ChIP-Seq experiments, measured photosynthetic parameters, chlorophyll contents and growth rates, and analyzed alterations in transcriptomics. We found that, although overexpression of BBX14 is deleterious under normal growth conditions, BBX14 is needed to acclimate plants to high light stress.BBX14is a direct target of GLK1, and RNA-Seq analysis suggests that BBX14 is involved in the circadian clock. Knockout ofBBX14results in a long-hypocotyl phenotype that depends on a retrograde signal, andBBX14expression during biogenic signaling requires GUN1. Finally, we clarify the role of BBX14 in GUN-type biogenic signaling. We conclude that BBX14 is an integrator of photomorphogenetic and biogenic signals, and suggest that BBX14 is a nuclear target of retrograde signals downstream of the GUN1/GLK1 module.

Floral scent is an important and genetically complex trait in horticultural plants. Tree peony (Paeonia × suffruticosa) originates in the Pan-Himalaya and has nine wild species divided into two subsections, Delavayanae and Vaginatae. Their flowers are beloved worldwide for their sweet floral fragrance, yet the flavor-related volatiles and underlying biosynthetic pathways remain unknown. Here, we characterized the volatile blends of all wild tree peony species and found that the flavor-related volatiles were highly divergent, but linalool was a unique monoterpene in subsect. Delavayanae. Further detection of volatiles in 97 cultivars with various genetic backgrounds showed that linalool was also the characteristic aroma component in Paeonia delavayi hybrid progenies, suggesting that linalool was conserved and dominant within subsect. Delavayanae and its hybrids, instead of species and cultivars from subsect. Vaginatae. Global transcriptome analysis of all wild tree peony species and 60 cultivars revealed five candidate genes that may be involved in key steps of linalool biosynthesis; especially the expressions of three TPS genes, PdTPS1, PdTPS2, and PdTPS4, were significantly positively correlated with linalool emissions across tree peony cultivars. Further biochemical evidence demonstrated that PdTPS1 and PdTPS4 were the pivotal genes determining the species-specific and cultivar-specific emission of linalool. This study revealed a new insight into floral scent divergence in tree peony and would greatly facilitate our understanding of the phylogeny and evolution of Paeonia.

Background Petal blotch is a unique ornamental trait in angiosperm families, and blotch in rose petal is rare and has great esthetic value. However, the cause of the formation of petal blotch in rose is still unclear. The influence of key enzyme genes and regulatory genes in the pigment synthesis pathways needs to be explored and clarified. Results In this study, the rose cultivar ‘Sunset Babylon Eyes’ with rose-red to dark red blotch at the base of petal was selected as the experimental material. The HPLC-DAD and UPLC-TQ-MS analyses indicated that only cyanidin 3,5-O-diglucoside (Cy3G5G) contributed to the blotch pigmentation of ‘Sunset Babylon Eyes’, and the amounts of Cy3G5G varied at different developmental stages. Only flavonols but no flavone were found in blotch and non-blotch parts. As a consequence, kaempferol and its derivatives as well as quercetin and its derivatives may act as background colors during flower developmental stages. Despite of the differences in composition, the total content of carotenoids in blotch and non-blotch parts were similar, and carotenoids may just make the petals show a brighter color. Transcriptomic data, quantitative real-time PCR and promoter sequence analyses indicated that RC7G0058400 (F3’H), RC6G0470600 (DFR) and RC7G0212200 (ANS) may be the key enzyme genes for the early formation and color deepening of blotch at later stages. As for two transcription factor, RC7G0019000 (MYB) and RC1G0363600 (WRKY) may bind to the promoters of critical enzyme genes, or RC1G0363600 (WRKY) may bind to the promoter of RC7G0019000 (MYB) to activate the anthocyanin accumulation in blotch parts of ‘Sunset Babylon Eyes’. Conclusions Our findings provide a theoretical basis for the understanding of the chemical and molecular mechanism for the formation of petal blotch in rose.

Neoxanthin (Neo), which is only bound to the peripheral antenna proteins of photosystem (PS) II, is a conserved carotenoid in all green plants. It has been demonstrated that Neo plays an important role in photoprotection and its deficiency fails to impact LHCII stability in vitro and indoor plant growth in vivo. Whether Neo is involved in maintaining the PSII complex structure or adaptive mechanisms for the everchanging environment has not yet been elucidated. In this study, the role of Neo in maintaining the structure and function of the PSII-LHCII supercomplexes was studied using Neo deficient Arabidopsis mutants. Our results show that Neo deficiency had little effect on the electron transport capacity and the plant fitness, but the PSII-LHCII supercomplexes were significantly impacted by the lack of Neo. In the absence of Neo, the M-type LHCII trimer cannot effectively associate with the C2 S2 -type PSII-LHCII supercomplexes even in moderate light conditions. Interestingly, Neo deficiency also leads to decreased PSII protein phosphorylation but rapid transition from state 1 to state 2. We suggest that Neo might enforce the interactions between LHCII and the minor antennas and that the absence of Neo makes M-type LHCII disassociate from the PSII complex, leading to the disassembly of the PSII-LHCII C2 S2 M2 supercomplexes, which results in alterations in the phosphorylation patterns of the thylakoid photosynthetic proteins and the kinetics of state transition.

Poplar, a woody perennial model, is a common and widespread tree genus. We cultivated two red leaf poplar varieties from bud mutation of Populus sp. Linn. ‘2025’ (also known as Zhonglin 2025, L2025 for shot): Populus deltoides varieties with bright red leaves (LHY) and completely red leaves (QHY). After measuring total contents of flavonoid, anthocyanin, chlorophyll and carotenoid metabolites, a liquid chromatography-electrospray ionization-tandem mass spectrometry system was used for the relative quantification of widely targeted metabolites in leaves of three poplar varieties. A total of 210 flavonoid metabolites (89 flavones, 40 flavonols, 25 flavanones, 18 anthocyanins, 16 isoflavones, 7 dihydroflavonols, 7 chalcones, 5 proanthocyanidins and 3 other flavonoid metabolites) were identified. Compared with L2025, 48 and 8 flavonoids were more and less abundant, respectively, in LHY, whereas 51 and 9 flavonoids were more and less abundant in QHY, respectively. On the basis of a comprehensive analysis of the metabolic network, gene expression levels were analyzed by deep sequencing to screen for potential reference genes for the red leaves. Most phenylpropanoid biosynthesis pathway-involved genes were differentially expressed among the examined varieties. Gene expression analysis also revealed several potential anthocyanin biosynthesis regulators including three MYB genes. The study results provide new insights into poplar flavonoid metabolites and represent the theoretical basis for future studies on leaf coloration in this model tree species.

Previous studies have shown that high light intensity can induce anthocyanin synthesis (AS) in petunia plants. To identify which kind of light quality plays a role in inducing such metabolic process, and what transcripts participate in controlling it, we carried out whole-transcriptome sequencing and analysis of petunia petals treated with different light-quality conditions. Among the red and white light treatments, a total of 2 205 differentially expressed genes and 15, 22, and 20 differentially expressed circRNAs, miRNAs, and lncRNAs, were identified respectively. The AS-related genes, including the structural genes CHSj, F3′H, F3′5′H, DFR, and ANS, and the regulatory genes AN4, DPL, PHZ and MYBx were found to be downregulated under red light condition compared with their levels under white light condition. Furthermore, the light photoreceptor Cryptochrome 3 (CRY3) and a series of light-dependent genes, such as PIF, HY5, and BBXs, were also determined to respond to the light treatments. The anthocyanin contents in early petunia petals under red light were significantly lower than that under white and blue light. The results of qRT-PCR further confirmed the expression pattern of some AS-related and light-response genes in response to different light quality. Yeast two-hybrid results showed that the key elements in the light signal pathway, HY5 can interact with BBX19, BBX24 and BBX25. And PHZ, the important AS regulator can induce anthocyanin synthesis in response to blue light quality from transient expression analysis in petunia petals. These findings presented here not only deepen our understanding of how light quality controls anthocyanin synthesis, but also allow us to explore potential target genes for improving pigment production in petunia flower petals.

The Arabidopsis genome is methylated in CG and non-CG (CHG, and CHH in which H stands for A, T, or C) sequence contexts. DNA methylation has been suggested to be critical for seed development, and CHH methylation patterns change during stratification and germination. In plants, CHH methylation occurs mainly through the RNA-directed DNA methylation (RdDM) pathway. To test for an involvement of the RdDM pathway in chloroplast development, we analyzed seedling greening and the maximum quantum yield of photosystem II (Fv/Fm) in Arabidopsis thaliana seedlings perturbed in components of that pathway. Neither seedling greening nor Fv/Fm in seedlings and adult plants were affected in this comprehensive set of mutants, indicating that alterations in the RdDM pathway do not affect chloroplast development. Application of inhibitors like lincomycin or norflurazon inhibits greening of seedlings and represses the expression of photosynthesis-related genes including LIGHT HARVESTING CHLOROPHYLL A/B BINDING PROTEIN1.2 (LHCB1.2) in the nucleus. Our results indicate that the LHCB1.2 promoter is poorly methylated under both control conditions and after inhibitor treatment. Therefore no correlation between LHCB1.2 mRNA transcription and methylation changes of the LHCB1.2 promoter could be established. Moreover, we conclude that perturbations in the RdDM pathway do not interfere with gun signaling.

RNA-directed DNA methylation (RdDM) helps to defend plants against invasive nucleic acids. In the canonical form of RdDM, 24-nt small interfering RNAs (siRNAs) are produced by DICER-LIKE 3 (DCL3). The siRNAs are loaded onto ARGONAUTE (AGO) proteins leading ultimately to de novo DNA methylation. Here, we introduce the Arabidopsis thaliana prors1 (LUC) transgenic system, in which 24-nt siRNAs are generated to silence the promoter-LUC construct. A forward genetic screen performed with this system identified, besides known components of RdDM (NRPD2A, RDR2, AGO4 and AGO6), the RNA-binding protein RBP45D. RBP45D is involved in CHH (where H is A, C or T) DNA methylation, and maintains siRNA production originating from the LUC transgene. RBP45D is localized to the nucleus, where it is associated with small nuclear RNAs (snRNAs) and small nucleolar RNAs (snoRNAs). RNA-Seq analysis showed that in CRISPR/Cas-mediated rbp-ko lines FLOWERING LOCUS C (FLC) mRNA levels are upregulated and several loci differentially spliced, among them FLM. In consequence, loss of RBP45D delays flowering, presumably mediated by the release of FLC levels and/or alternative splicing of FLM. Moreover, because levels and processing of transcripts of known RdDM genes are not altered in rbp-ko lines, RBP45D should have a more direct function in transgene silencing, probably independent of the canonical RdDM pathway. We suggest that RBP45D facilitates siRNA production by stabilizing either the precursor RNA or the slicer protein. Alternatively, RBP45D could be involved in chromatin modifications, participate in retention of Pol IV transcripts and/or in Pol V-dependent lncRNA retention in chromatin to enable their scaffold function.

Paeonia species are important ornamental plants, including three types: tree peony, herbaceous peony, and Itoh hybrid peony. Paeonia with yellow color is desired and becoming popular. However, the chemical mechanism of the formation of yellow flowers in Paeonia is still unclear. In this study, 14 representative samples were selected: four samples of three species of Paeonia, four herbaceous peony cultivars, three lutea hybrid tree peony cultivars, and three Itoh hybrid peony cultivars. The petal extracts of the samples were determined by HPLC-DAD and HPLC-Q-TOF-MS/MS. In total, 29 flavonoids were isolated and identified, including 28 flavonol glycosides and one chalcone derivative. There were significant differences in the composition and content of flavonoids in petals of different cultivars (species). The total content of flavonoids was between 19.430 and 143.043 mg • g−1 DW. Flavonol glycosides were detected in all samples. Chalconaringenin 2′-O-glucoside was detected from one herbaceous peony cultivar ‘Golden Wheel’ lutea hybrid tree peony cultivars, and Itoh peony cultivars. The content of chalconaringenin 2′-O-glucoside in the samples was more than 43% of total flavonoids. The pigment type and content of lutea hybrid tree peonies and Itoh hybrid peonies are similar. Total flavonoids, especially quercetin 3-O-galloylglucoside and chalconaringenin 2′-O-glucoside contribute greatly to the formation of yellow flowers of Paeonia. The results of this study provide a comprehensive understanding of the chemical mechanism for yellow flower coloration of Paeonia, and lay the foundation for yellow flower breeding of Paeonia.

Singlet oxygen ( 1 O 2 ), the major reactive oxygen species (ROS) produced in chloroplasts, has been demonstrated recently to be a highly versatile signal that induces various stress responses. In the fluorescent ( flu ) mutant, its release causes seedling lethality and inhibits mature plant growth. However, these drastic phenotypes are suppressed when EXECUTER1 (EX1) is absent in the flu ex1 double mutant. We identified SAFEGUARD1 (SAFE1) in a screen of ethyl methanesulfonate (EMS) mutagenized flu ex1 plants for suppressor mutants with a flu -like phenotype. In flu ex1 safe1 , all 1 O 2 -induced responses, including transcriptional rewiring of nuclear gene expression, return to levels, such as, or even higher than, those in flu . Without SAFE1, grana margins (GMs) of chloroplast thylakoids (Thys) are specifically damaged upon 1 O 2 generation and associate with plastoglobules (PGs). SAFE1 is localized in the chloroplast stroma, and release of 1 O 2 induces SAFE1 degradation via chloroplast-originated vesicles. Our paper demonstrates that flu -produced 1 O 2 triggers an EX1-independent signaling pathway and proves that SAFE1 suppresses this signaling pathway by protecting GMs.

Water lilies belong to the angiosperm order Nymphaeales. Amborellales, Nymphaeales and Austrobaileyales together form the so-called ANA-grade of angiosperms, which are extant representatives of lineages that diverged the earliest from the lineage leading to the extant mesangiosperms1–3. Here we report the 409-megabase genome sequence of the blue-petal water lily (Nymphaea colorata). Our phylogenomic analyses support Amborellales and Nymphaeales as successive sister lineages to all other extant angiosperms. The N. colorata genome and 19 other water lily transcriptomes reveal a Nymphaealean whole-genome duplication event, which is shared by Nymphaeaceae and possibly Cabombaceae. Among the genes retained from this whole-genome duplication are homologues of genes that regulate flowering transition and flower development. The broad expression of homologues of floral ABCE genes in N. colorata might support a similarly broadly active ancestral ABCE model of floral organ determination in early angiosperms. Water lilies have evolved attractive floral scents and colours, which are features shared with mesangiosperms, and we identified their putative biosynthetic genes in N. colorata. The chemical compounds and biosynthetic genes behind floral scents suggest that they have evolved in parallel to those in mesangiosperms. Because of its unique phylogenetic position, the N. colorata genome sheds light on the early evolution of angiosperms., The genome of the tropical blue-petal water lily Nymphaea colorata and the transcriptomes from 19 other Nymphaeales species provide insights into the early evolution of angiosperms.

Arabidopsis thaliana contains 13 fibrillins (FBNs), which are all localized to chloroplasts. FBN1 and FBN2 are involved in photoprotection of photosystem II, and FBN4 and FBN5 are thought to be involved in plastoquinone transport and biosynthesis, respectively. The functions of the other FBNs remain largely unknown. To gain insight into the function of FBN6, we performed coexpression and Western analyses, conducted fluorescence and transmission electron microscopy, stained reactive oxygen species (ROS), measured photosynthetic parameters and glutathione levels, and applied transcriptomics and metabolomics. Using coexpression analyses, FBN6 was identified as a photosynthesis‐associated gene. FBN6 is localized to thylakoid and envelope membranes, and its knockout results in stunted plants. The delayed‐growth phenotype cannot be attributed to altered basic photosynthesis parameters or a reduced CO2 assimilation rate. Under moderate light stress, primary leaves of fbn6 plants begin to bleach and contain enlarged plastoglobules. RNA sequencing and metabolomics analyses point to an alteration in sulfate reduction in fbn6. Indeed, glutathione content is higher in fbn6, which in turn confers cadmium tolerance of fbn6 seedlings. We conclude that loss of FBN6 leads to perturbation of ROS homeostasis. FBN6 enables plants to cope with moderate light stress and affects cadmium tolerance.

Acer truncatum Bunge and Xanthoceras sorbifolium Bunge are small deciduous trees distributed in East Asia and have high ecological and nutrient value due to their strong environmental adaptability and seed oil abundant in nervonic acid and unsaturated fatty acids. However, their natural distribution remains unclear, which will also be affected by the changing climatic conditions. The main purpose of this study was to map and predict the current and future potential suitable habitats of these two species using MaxEnt based on the presence location of species and environmental variables. The results showed that A. truncatum was more suitable for warm and humid climates and was more durable to climate change compared to X. sorbifolium. Under the current environmental conditions, the suitable habitat of A. truncatum was mainly concentrated in Inner Mongolia Plateau, Loess Plateau, Sichuan Basin, Northeast Plain, North China Plain, Korean Peninsula, as well as Japan, with an area of 115.39 × 104 km2. X. sorbifolium was mainly distributed in Inner Mongolia Plateau and Loess Plateau with an area of 146.15 × 104 km2. Under future climate scenarios, the model predicted that higher concentrations of greenhouse gas emissions could result in greater expansion of the potential distribution of both species. Meanwhile, the study also revealed that the two species migrated to the north by east to varying degrees with the change in suitable habitats. This work could provide scientific basis for resource protection and utilization of the two economic forest trees.

SummaryRNA-directed DNA methylation (RdDM) helps to defend plants against invasive nucleic acids. In the canonical form of RdDM, 24-nt small interfering RNAs (siRNAs) are produced by DICER-LIKE 3 (DCL3). Here, we describe the Arabidopsis thaliana prors1 (LUC) transgenic system, in which transcriptional gene silencing (TGS) is independent of DLC3. A forward genetics screen performed with this system identified both known components of RdDM, and the RNA-binding protein RBP45D. RBP45D promotes DNA methylation, and its loss delays flowering, especially at high temperature, presumably mediated by elevated FLC levels. RBP45D is localized to the nucleus, where it is associated with snRNAs and snoRNAs. RBP45D maintains siRNA production originating from the LUC transgene, but does not alter mRNA levels or affect processing of transcripts of known RdDM genes. We suggest that RBPD45 facilitates DCL3-independent siRNA production by stabilising either the precursor RNA or the – as yet unidentified – slicer protein.

Phytosterols exhibit a wide range of pharmacological activities and have no side-effects, which have attracted more and more attention. In this study, two pre-treatment methods (alkaline hydrolysis and acid-alkali hydrolysis) were performed in parallel for the first time to investigate the effects on phytosterol analysis. The aim is to develop an analytical method for phytosterols in pollen and anther wall of tree peony (Paeonia ostii 'Fengdan') by gas chromatography-mass spectrometry. The result indicated that the contents of phytosterols in pollen (3390.02 mg/100 g DW) and anther wall (929.70 mg/100 g DW) of P. ostii 'Fengdan' were relatively high. Meanwhile, eleven phytosterols were identified, among which five phytosterols were first identified in tree peony pollen. Moreover, the effects of wall breaking and different developmental stages on phytosterol contents of pollen and anther wall of P. ostii 'Fengdan' were also discussed. The result showed that wall breaking was beneficial to sterol detection of pollen, but not necessary for anther wall. For the best harvest time, the stage of S2 had the highest content of phytosterols. In conclusion, this study successfully establishes an analytical method for phytosterols by gas chromatography-mass spectrometry, and lays a foundation for the development and utilization of pollen and anther wall of P. ostii 'Fengdan' in functional foods and pharmaceutical industry.

Paeonia cultivars are famous ornamental plants, and some of them are also traditional Chinese medicinal resources. Intersubgeneric hybrids of Paeonia (IHPs) are formed by the hybridization of herbaceous peony (Paeonia lactiflora) and tree peony (Paeonia×suffruticosa or lutea hybrid tree peony). The phenotypic characteristics of IHPs are similar to those of herbaceous peony, and their root systems are large and vigorous. However, their medicinal value has not been reported yet. In this study, the roots of eight IHP samples were analyzed by high performance liquid chromatography quadrupole time-of-flight mass spectrometry (HPLC-Q-TOF-MS/MS). A total of 18 compounds were identified, including phenols, paeonols, monoterpene glycosides, and tannins. The contents of monoterpene glycosides and tannins in IHPs were higher than herbaceous peony and tree peony, exceeding 44.76 mg/g DW and 11.50 mg/g DW, respectively. Three IHPs, 'Prairie Charm', 'Garden Treasure', and 'Yellow Emperor', with more types and a higher content of medicinal compounds, were screened out by cluster analysis. These IHPs have considerable potential for the development of medicinal resources.

Elm fruits were once an important food source in the years of famine. Research on the functional compounds in elm fruits was almost unavailable. In this study, we established an efficient high-performance liquid chromatography method for the simultaneous separation of eight chlorogenic acids and 28 flavonoids in elm fruits for the first time. Total flavonoid contents ranged from 286 mg/100 g (Ulmus laciniata) to 1228 mg/100 g (U. pumila). High concentrations of rutin, quercetin 3-O-glucoside, and kaempferol derivatives were present in U. laevis, U. castaneifolia, and U. pumila, respectively. Furthermore, the fruit extracts of U. americana, U. castaneifolia, U. davidiana, and U. pumila showed higher antioxidant activity. These results suggest that fruits of these species can be used as bioresources for the extraction of the corresponding functional compounds. This work provides informative data and can be an important reference for future research on elm fruits as a renewed food resource.

Sedum plumbizincicola is able to hyperaccumulate cadmium (Cd), a nonessential and highly toxic metal, in the above-ground tissues, but the mechanisms for its Cd hypertolerance are not fully understood. Here, we show that the heavy metal ATPase 1 (SpHMA1) of S. plumbizincicola plays an important role in chloroplast Cd detoxification. Compared with the HMA1 ortholog in the Cd nonhyperaccumulating ecotype of Sedum alfredii, the expression of SpHMA1 in the leaves of S. plumbizincicola was >200 times higher. Heterologous expression of SpHMA1 in Saccharomyces cerevisiae increased Cd sensitivity and Cd transport activity in the yeast cells. The SpHMA1 protein was localized to the chloroplast envelope. SpHMA1 RNA interference transgenic plants and CRISPR/Cas9-induced mutant lines showed significantly increased Cd accumulation in the chloroplasts compared with wild-type plants. Chlorophyll fluorescence imaging analysis revealed that the photosystem II of SpHMA1 knockdown and knockout lines suffered from a much higher degree of Cd toxicity than wild type. Taken together, these results suggest that SpHMA1 functions as a chloroplast Cd exporter and protects photosynthesis by preventing Cd accumulation in the chloroplast in S. plumbizincicola and hyperexpression of SpHMA1 is an important component contributing to Cd hypertolerance in S. plumbizincicola.

Induction and secretion of acid phosphatases is an adaptive response of plants to phosphate starvation. The secreted acid phosphatases are believed to scavenge phosphate from organophosphate compounds in the rhizosphere, thereby increasing phosphate availability for plant absorption. To date, however, all of the characterized phosphate starvation-induced secreted acid phosphatases in plants belong to a unique acid phosphatases subfamily, called purple acid phosphatase. In this work, we identified a phosphate starvation-induced secreted acid phosphatase in Arabidopsis as a vegetative storage protein, AtVSP3. AtVSP3 exists as a monomer with molecular weight of 29 kDa. The activity of recombinant AtVSP3 protein is activated by Mg2+, Co2+, and Ca2+. AtVSP3 has an optimal pH of 6.5 for its APase activity and is relatively thermostable. The transcription of AtVSP3 is induced in roots by phosphate starvation, and the accumulation of AtVSP3 protein is high in roots and siliques. Additional research is needed to determine the function of AtVSP3 in plant responses to stress conditions.

Lotus plumule, the embryo of the seed of the sacred lotus (Nelumbo nucifera), contains a high accumulation of secondary metabolites including flavonoids and possesses important pharmaceutical value. Flavonoid C-glycosides, which accumulate exclusively in lotus plumule, have attracted considerable attention in recent decades due to their unique chemical structure and special bioactivities. As well as mono-C-glycosides, lotus plumule also accumulates various kinds of di-C-glycosides by mechanisms which are as yet unclear. In this study we identified two C-glycosyltransferase (CGT) genes by mining sacred lotus genome data and provide in vitro and in planta evidence that these two enzymes (NnCGT1 and NnCGT2, also designated as UGT708N1 and UGT708N2, respectively) exhibit CGT activity. Recombinant UGT708N1 and UGT708N2 can C-glycosylate 2-hydroxyflavanones and 2-hydroxynaringenin C-glucoside, forming flavone mono-C-glycosides and di-C-glycosides, respectively, after dehydration. In addition, the above reactions were successfully catalysed by cell-free extracts from tobacco leaves transiently expressing NnCGT1 or NnCGT2. Finally, enzyme assays using cell-free extracts of lotus plumule suggested that flavone di-C-glycosides (vicenin-1, vicenin-3, schaftoside and isoschaftoside) are biosynthesized through sequentially C-glucosylating and C-arabinosylating/C-xylosylating 2-hydroxynaringenin. Taken together, our results provide novel insights into the biosynthesis of flavonoid di-C-glycosides by proposing a new biosynthetic pathway for flavone C-glycosides in N. nucifera and identifying a novel uridine diphosphate-glycosyltransferase (UGT708N2) that specifically catalyses the second glycsosylation, C-arabinosylating and C-xylosylating 2-hydroxynaringenin C-glucoside.

Since the recognition of the reactive oxygen species singlet oxygen (

Since the recognition of the reactive oxygen species singlet oxygen (1O2) as a versatile signal that induces various stress responses, the mechanisms underlying 1O2-induced signaling transduction pathways have become the subject of much current research. This in turn highlights the need for reliable detection methods for 1O2. Here we describe a protocol for the detection of 1O2 using a commercially available fluorescent probe (Singlet Oxygen Sensor Green) and provide a simple method for direct visualization and quantification of the 1O2-evolving photosensitizer protochlorophyllide in the Arabidopsis fluorescent mutant.

Members of the genusPaeonia, which consists of globally renowned ornamentals and traditional medicinal plants with a rich history spanning over 1500 years, are widely distributed throughout the Northern Hemisphere. Since 1900, over 2200 new horticulturalPaeoniacultivars have been created by the discovery and breeding of wild species. However, information pertaining toPaeoniabreeding is considerably fragmented, with fundamental gaps in knowledge, creating a bottleneck in effective breeding strategies. This review systematically introducesPaeoniagermplasm resources, including wild species and cultivars, summarizes the breeding strategy and results of eachPaeoniacultivar group, and focuses on recent progress in the isolation and functional characterization of structural and regulatory genes related to important horticultural traits. Perspectives pertaining to the resource protection and utilization, breeding and industrialization ofPaeoniain the future are also briefly discussed.