Integrated mass spectrometry imaging and single-cell transcriptome atlas strategies provide novel insights into taxoid biosynthesis and transport in Taxus mairei stems.

Taxol, which is a widely used important chemotherapeutic agent, was originally isolated from Taxus stem barks. However, little is known about the precise distribution of taxoids and the transcriptional regulation of taxoid biosynthesis across Taxus stems. Here, we used MALDI-IMS analysis to visualize the taxoid distribution across Taxus mairei stems and single-cell RNA sequencing to generate expression profiles. A single-cell T. mairei stem atlas was created, providing a spatial distribution pattern of Taxus stem cells. Cells were reordered using a main developmental pseudotime trajectory which provided temporal distribution patterns in Taxus stem cells. Most known taxol biosynthesis-related genes were primarily expressed in epidermal, endodermal, and xylem parenchyma cells, which caused an uneven taxoid distribution across T. mairei stems. We developed a single-cell strategy to screen novel transcription factors (TFs) involved in taxol biosynthesis regulation. Several TF genes, such as endodermal cell-specific MYB47 and xylem parenchyma cell-specific NAC2 and bHLH68, were implicated as potential regulators of taxol biosynthesis. Furthermore, an ATP-binding cassette family transporter gene, ABCG2, was proposed as a potential taxoid transporter candidate. In summary, we generated a single-cell Taxus stem metabolic atlas and identified molecular mechanisms underpinning the cell-specific transcriptional regulation of the taxol biosynthesis pathway.

Identification and functional analysis of cation-efflux transporter 1 from Brassica juncea L.

BACKGROUND: Brassica juncea behaves as a moderate-level accumulator of various heavy metal ions and is frequently used for remediation. To investigate the roles of metal ion transporters in B. juncea, a cation-efflux family gene, BjCET1, was cloned and functionally characterized. RESULTS: BjCET1 contains 382 amino acid residues, including a signature motif of the cation diffusion facilitator protein family, six classic trans-membrane-spanning structures and a cation-efflux domain. A phylogenetic analysis showed that BjCET1 has a high similarity level with metal tolerance proteins from other Brassica plants, indicating that this protein family is highly conserved in Brassica. BjCET1 expression significantly increased at very early stages during both cadmium and zinc treatments. Green fluorescence detection in transgenic tobacco leaves revealed that BjCET1 is a plasma membrane-localized protein. The heterologous expression of BjCET1 in a yeast mutant increased the heavy-metal tolerance and decreased the cadmium or zinc accumulations in yeast cells, suggesting that BjCET1 is a metal ion transporter. The constitutive expression of BjCET1 rescued the heavy-metal tolerance capability of transgenic tobacco plants. CONCLUSIONS: The data suggest that BjCET1 is a membrane-localized efflux transporter that plays essential roles in heavy metal ion homeostasis and hyper-accumulation.

Comparative metabolomic and transcriptomic analyses revealed the differential accumulation of secondary metabolites during the ripening process of acerola cherry (Malpighia emarginata) fruit.

BACKGROUND: Acerola cherry is a famous functional fruit containing plentiful antioxidants and other nutrients. However, studies on the variations among nutrients during the ripening process of acerola fruit are scare. RESULTS: Comparative metabolomic and transcriptomic analyses were performed and identified 31 331 unigenes and 1896 annotated metabolite features in acerola cherry fruit. K Kyoto Encyclopedia of Genes and Genomes enrichment analysis showed that several antioxidant and nutrient-related metabolic pathways, such as the flavonoids, vitamins, carotenoids, amino acids, and fatty acids metabolic pathways, were significantly changed during the ripening process. The metabolites related to the vitamin, carotenoid, and fatty acid metabolic pathways were downregulated during the ripening process. Several flavonoid biosynthesis-related genes (including dihydroflavonol 4-reductase, chalcone synthase, flavanone 3-hydroxylase, and anthocyanidin synthase), were significantly upregulated, suggesting their essential functions in the accumulation of flavonoids in mature fruit. CONCLUSION: Most of the vitamin and carotenoid metabolism-related metabolites significantly accumulated in immature fruit, suggesting that immature acerola fruit is a good material for the extraction of vitamins and carotenoids. For macronutrients, most of the amino acids accumulated in mature fruit and most of the fatty acids greatly accumulated in immature fruit. Our data revealed the differential accumulation of antioxidants and nutrients during the ripening process of acerola cherry fruit. © 2021 Society of Chemical Industry.

Tissue-specific study across the stem of Taxus media identifies a phloem-specific TmMYB3 involved in the transcriptional regulation of paclitaxel biosynthesis.

Taxus stem barks can be used for extraction of paclitaxel. However, the composition of taxoids across the whole stem and the stem tissue-specificity of paclitaxel biosynthesis-related enzymes remain largely unknown. We used cultivated Taxus media trees for analyses of the chemical composition and protein of major stem tissues by an integrated metabolomic and proteomic approach, and the role of TmMYB3 in paclitaxel biosynthesis was investigated. The metabolomic landscape analysis showed differences in stem tissue-specific accumulation of metabolites. Phytochemical analysis revealed that there is high accumulation of paclitaxel in the phloem. Ten key enzymes involved in paclitaxel biosynthesis were identified, most of which are predominantly produced in the phloem. The full-length sequence of TmMYB3 and partial promoter sequences of five paclitaxel biosynthesis-related genes were isolated. Several MYB recognition elements were found in the promoters of TBT, DBTNBT and TS. Further in vitro and in vivo investigations indicated that TmMYB3 is involved in paclitaxel biosynthesis by activating the expression of TBT and TS. Differences in the taxoid composition of different stem tissues suggest that the whole stem of T. media has potential for biotechnological applications. Phloem-specific TmMYB3 plays a role in the transcriptional regulation of paclitaxel biosynthesis, and may explain the phloem-specific accumulation of paclitaxel.

Omic analysis of the endangered Taxaceae species Pseudotaxus chienii revealed the differences in taxol biosynthesis pathway between Pseudotaxus and Taxus yunnanensis trees.

BACKGROUND: Taxol is an efficient anticancer drug accumulated in Taxus species. Pseudotaxus chienii is an important member of Taxaceae, however, the level of six taxoids in P. chienii is largely unknown. RESULTS: High accumulation of 10-DAB, taxol, and 7-E-PTX suggested that P. chienii is a good taxol-yielding species for large-scale cultivation. By the omics approaches, a total of 3,387 metabolites and 61,146 unigenes were detected and annotated. Compared with a representative Taxus tree (Taxus yunnanensis), most of the differentially accumulated metabolites and differential expressed genes were assigned into 10 primary and secondary metabolism pathways. Comparative analyses revealed the variations in the precursors and intermediate products of taxol biosynthesis between P. chienii and T. yunnanensis. Taxusin-like metabolites highly accumulated in P. chienii, suggesting a wider value of P. chienii in pharmaceutical industry. CONCLUSIONS: In our study, the occurrence of taxoids in P. chienii was determined. The differential expression of key genes involved in the taxol biosynthesis pathway is the major cause of the differential accumulation of taxoids. Moreover, identification of a number of differentially expressed transcription factors provided more candidate regulators of taxol biosynthesis. Our study may help to reveal the differences between Pseudotaxus and Taxus trees, and promote resource utilization of the endangered and rarely studied P. chienii.

Bioactive compounds induced in Physalis angulata L. by methyl-jasmonate: an investigation of compound accumulation patterns and biosynthesis-related candidate genes.

KEY MESSAGE: We employed both metabolomic and transcriptomic approaches to explore the accumulation patterns of physalins, flavonoids and chlorogenic acid in Physalis angulata and revealed the genes associated with the biosynthesis of bioactive compounds under methyl-jasmonate (MeJA) treatment. Physalis angulata L. is an annual Solanaceae plant with a number of medicinally active compounds. Despite the potential pharmacological benefits of P. angulata, the scarce genomic information regarding this plant has limited the studies on the mechanisms of bioactive compound biosynthesis. To facilitate the basic understanding of the main chemical constituent biosynthesis pathways, we performed both metabolomic and transcriptomic approaches to reveal the genes associated with the biosynthesis of bioactive compounds under methyl-jasmonate (MeJA) treatment. Untargeted metabolome analysis showed that most physalins, flavonoids and chlorogenic acid were significantly upregulated. Targeted HPLC-MS/MS analysis confirmed variations in the contents of two important representative steroid derivatives (physalins B and G), total flavonoids, neochlorogenic acid, and chlorogenic acid between MeJA-treated plants and controls. Transcript levels of a few steroid biosynthesis-, flavonoid biosynthesis-, and chlorogenic acid biosynthesis-related genes were upregulated, providing a potential explanation for MeJA-induced active ingredient synthesis in P. angulata. Systematic correlation analysis identified a number of novel candidate genes associated with bioactive compound biosynthesis. These results may help to elucidate the regulatory mechanism underlying MeJA-induced active compound accumulation and provide several valuable candidate genes for further functional study.

Identification and expression analysis of auxin-responsive GH3 family genes in Chinese hickory (Carya cathayensis) during grafting.

The GH3 genes play vital roles in auxin homeostasis by conjugating excess auxin to amino acids. However, how GH3 genes function during grafting in Chinese hickory (Carya cathayensis) is largely unknown. Here, based on the transcriptome database, a comprehensive identification and expression profiling analysis of 12 GH3 genes in Chinese hickory were performed. Phylogenetic analysis indicated that CcGH3-x exists in a specific subfamily. To understand the roles of CcGH3 genes, tissue-specific expression and the response to different phytohormones were determined. Expression profiles of GH3 genes of Chinese hickory during grafting were analysed. The data suggested that 10 CcGH3 genes were down-regulated at an early stage of grafting, indicating that auxin homeostasis regulated by the CcGH3 family might be inhibited at initial stages. At the completion of grafting, expression levels of members of the CcGH3 family were restored to normal levels. Endogenous auxin levels were also measured, and the data showed that free auxin decreased to the lowest level at an early stage of grafting, and then increased during grafting. Auxin amino acid conjugation increased at an early stage of grafting in rootstock, and then decreased with progression of the graft union. Our results demonstrate that the reduced expression of CcGH3 family genes during grafting might contribute to the release of free auxin, making an important contribution to the recovery of auxin levels after grafting.

Quantitative succinyl-proteome profiling of Chinese hickory (Carya cathayensis) during the grafting process.

BACKGROUND: Chinese hickory (Carya cathayensis) is a popular nut plant having high economic value. Grafting is applied to accelerate the transition from vegetative phase to reproductive phase. Lysine succinylation occurs frequently in the proteins associated with metabolic pathways, which may participate in the regulation of the grafting process. However, the exact regulatory mechanism underlying grafting process in Chinese hickory has not been studied at post-translational modification level. RESULTS: A comprehensive proteome-wide lysine succinylation profiling of Chinese hickory was explored by a newly developed method combining affinity enrichment and high-resolution LC-MS/MS. In total, 259 succinylation sites in 202 proteins were identified, representing the first comprehensive lysine succinylome in Chinese hickory. The succinylation was biased to occur in the cytosolic proteins of Chinese hickory. Moreover, four conserved succinylation motifs were identified in the succinylated peptides. Comparison of two grafting stages of Chinese hickory revealed that the differential expressed succinylated proteins were mainly involved in sugar metabolism, carbon fixation, amino acid metabolism and plant-pathogen interaction. Besides, seven heat shock proteins (HSPs) with 11 succinylation sites were also identified, all of which were observed to be up-regulated during the grafting process. CONCLUSIONS: Succinylation of the proteins involved in amino acid biosynthesis might be required for a successful grafting. Succinylated HSPs might play a role in stress tolerance of the grafted Chinese hickory plants. Our results can be a good resource for functional validation of the succinylated proteins and a starting point for the investigation of molecular mechanisms during lysine succinylation occurring at grafting site.

Transcriptome analyses provide insights into the expression pattern and sequence similarity of several taxol biosynthesis-related genes in three Taxus species.

BACKGROUND: Taxol is an efficient anticancer drug; however, the accumulation of taxoids can vary hugely among Taxus species. The mechanism underlying differential accumulation of taxoids is largely unknown. Thus, comparative analysis of the transcriptomes in three Taxus species, including T. media, T. mairei and T. cuspidata, was performed. RESULTS: KEGG enrichment analysis revealed that the diterpenoid biosynthesis and cytochrome P450 pathways were significantly enriched in different comparisons. Differential expressions of these taxol biosynthesis related genes might be a potential explanation for the interspecific differential accumulation of taxol and its derivatives. Besides, the sequences of several MEP pathway-associated genes, such as DXS, DXR, MCT, CMK, MDS, HDS, HDR, IPPI, and GGPPS, were re-assembled based on independent transcriptomes from the three Taxus species. Phylogenetic analysis of these MEP pathway-associated enzymes also showed a high sequence similarity between T. media and T. cuspidata. Moreover, 48 JA-related transcription factor (TF) genes, including 10 MYBs, 5 ERFs, 4 RAPs, 3 VTCs, and 26 other TFs, were analyzed. Differential expression of these JA-related TF genes suggested distinct responses to exogenous JA applications in the three Taxus species. CONCLUSIONS: Our results provide insights into the expression pattern and sequence similarity of several taxol biosynthesis-related genes in three Taxus species. The data give us an opportunity to reveal the mechanism underlying the variations in the taxoid contents and to select the highest-yielding Taxus species.

Comparative metabolomic analysis reveals the variations in taxoids and flavonoids among three Taxus species.

BACKGROUND: Trees of the genus Taxus are highly valuable medicinal plants with multiple pharmacological effects on various cancer treatments. Paclitaxel from Taxus trees is an efficient and widely used anticancer drug, however, the accumulation of taxoids and other active ingredients can vary greatly among Taxus species. In our study, the metabolomes of three Taxus species have been investigated. RESULTS: A total of 2246 metabolites assigned to various primary and secondary metabolic pathways were identified using an untargeted approach. Analysis of differentially accumulated metabolites identified 358 T. media-, 220 T. cuspidata-, and 169 T. mairei-specific accumulated metabolites, respectively. By searching the metabolite pool, 7 MEP pathway precursors, 11 intermediates, side chain products and derivatives of paclitaxel, and paclitaxel itself were detected. Most precursors, initiated intermediates were highly accumulated in T. mairei, and most intermediate products approaching the end point of taxol biosynthesis pathway were primarily accumulated in T. cuspidata and T. media. Our data suggested that there were higher-efficiency pathways to paclitaxel in T. cuspidata and T. media compared with in T. mairei. As an important class of active ingredients in Taxus trees, a majority of flavonoids were predominantly accumulated in T. mairei rather than T. media and T. cuspidata. The variations in several selected taxoids and flavonoids were confirmed using a targeted approach. CONCLUSIONS: Systematic correlativity analysis identifies a number of metabolites associated with paclitaxel biosynthesis, suggesting a potential negative correlation between flavonoid metabolism and taxoid accumulation. Investigation of the variations in taxoids and other active ingredients will provide us with a deeper understanding of the interspecific differential accumulation of taxoids and an opportunity to accelerate the highest-yielding species breeding and resource utilization.

Comparative proteomic analysis provides novel insights into the regulation mechanism underlying papaya (Carica papaya L.) exocarp during fruit ripening process.

BACKGROUND: Papaya (Carica papaya L.) is a popular climacteric fruit, undergoing various physico-chemical changes during ripening. Although papaya is widely cultivated and consumed, few studies on the changes in metabolism during its ripening process at the proteasome level have been performed. Using a newly developed TMT-LCMS analysis, proteomes of papaya fruit at different ripening stages were investigated. RESULTS: In total, 3220 proteins were identified, of which 2818 proteins were quantified. The differential accumulated proteins (DAPs) exhibited various biological functions and diverse subcellular localizations. The KEGG enrichment analysis showed that various metabolic pathways were significantly altered, particularly in flavonoid and fatty acid metabolisms. The up-regulation of several flavonoid biosynthesis-related proteins may provide more raw materials for pigment biosynthesis, accelerating the color variation of papaya fruit. Variations in the fatty acid metabolism- and cell wall degradation-related proteins were investigated during the ripening process. Furthermore, the contents of several important fatty acids were determined, and increased unsaturated fatty acids may be associated with papaya fruit volatile formation. CONCLUSIONS: Our data may give an intrinsic explanation of the variations in metabolism during the ripening process of papaya fruit.

Comparative transcriptomic analysis reveal the regulation mechanism underlying MeJA-induced accumulation of alkaloids in Dendrobium officinale.

Dendrobium officinale is a traditional medicinal herb with a variety of bioactive components. Alkaloid is one of the major active ingredients of Dendrobium plants, and its immune regulatory effects have been well-studied. Although a number of genes involved in the biosynthetic pathway of alkaloids have been elucidated, the regulation mechanism underlying the methyl-jasmonate (MeJA)-induced accumulation of alkaloids in D. officinale is largely unknown. In our study, a total of 4,857 DEGs, including 2,943 up- and 1,932 down-regulated genes, were identified between the control and MeJA-treated groups. Kyoto Encyclopedia of Genes and Genomes annotation showed that a number of DEGs were associated with the putative alkaloid biosynthetic pathway in D. officinale. The main group of Dendrobium alkaloids are sesquiterpene alkaloids, which are the downstream products of mevalonate (MVA) and methylerythritol 4-phosphate (MEP) pathway. Several MVA and MEP pathway genes were significantly up-regulated by the MeJA treatment, suggesting an active precursor supply for the alkaloid biosynthesis under MeJA treatment. A number of MeJA-induced P450 family genes, aminotransferase genes and methyltransferase genes were identified, providing several important candidates to further elucidate the sesquiterpene alkaloid biosynthetic pathway of D. officinale. Furthermore, a large number of MeJA-induced transcript factor encoding genes were identified, suggesting a complex genetic network affecting the sesquiterpene alkaloid metabolism in D. officinale. Our data aids to reveal the regulation mechanism underlying the MeJA-induced accumulation of sesquiterpene alkaloids in D. officinale.

Comparative metabolomics reveals the metabolic variations between two endangered Taxus species (T. fuana and T. yunnanensis) in the Himalayas.

BACKGROUND: Plants of the genus Taxus have attracted much attention owing to the natural product taxol, a successful anti-cancer drug. T. fuana and T. yunnanensis are two endangered Taxus species mainly distributed in the Himalayas. In our study, an untargeted metabolomics approach integrated with a targeted UPLC-MS/MS method was applied to examine the metabolic variations between these two Taxus species growing in different environments. RESULTS: The level of taxol in T. yunnanensis is much higher than that in T. fuana, indicating a higher economic value of T. yunnanensis for taxol production. A series of specific metabolites, including precursors, intermediates, competitors of taxol, were identified. All the identified intermediates are predominantly accumulated in T. yunnanensis than T. fuana, giving a reasonable explanation for the higher accumulation of taxol in T. yunnanensis. Taxusin and its analogues are highly accumulated in T. fuana, which may consume limited intermediates and block the metabolic flow towards taxol. The contents of total flavonoids and a majority of tested individual flavonoids are significantly accumulated in T. fuana than T. yunnanensis, indicating a stronger environmental adaptiveness of T. fuana. CONCLUSIONS: Systemic metabolic profiling may provide valuable information for the comprehensive industrial utilization of the germplasm resources of these two endangered Taxus species growing in different environments.

Development of SCoT-Based SCAR Marker for Rapid Authentication of Taxus Media.

Taxus media is an important species in the family Taxaceae with high medicinal and commercial value. Overexploitation and illegal trade have led T. media to a severe threat of extinction. In addition, T. media and other Taxus species have similar morphological traits and are easily misidentified, particularly during the seedling stage. The purpose of this study is to develop a species-specific marker for T. media. Through a screening of 36 start codon targeted (SCoT) polymorphism primers, among 15 individuals of 4 Taxus species (T. media, T. chinensis, T. cuspidate and T. fuana), a clear species-specific DNA fragment (amplified by primer SCoT3) for T. media was identified. After isolation and sequencing, a DNA sequence with 530 bp was obtained. Based on this DNA fragment, a primer pair for the sequence-characterized amplified region marker was designed and named MHSF/MHSR. PCR analysis with primer pair MHSF/MHSR revealed a clear amplified band for all individuals of T. media but not for T. chinensis, T. cuspidate and T. fuana. Therefore, this marker can be used as a quick, efficient and reliable tool to identify T. media among other related Taxus species. The results of this study will lay an important foundation for the protection and management of T. media as a natural resource.

[Application of DNA molecular marker technologies in study of medicinal Physalis species].

As traditional Chinese medicinal herbs, Physalis plants have a variety of pharmacological activities, such as anti-inflammatory, anti-oxidant, and anti-cancer effects, and have been used for the treatment of malaria, rheumatism, hepatitis, asthma, and cancer. In addition to the medicinal value, many Physalis species are also the high-grade nutrition health care fruits, can be made canned and candied etc. In the study, the application progress of DNA molecular marker technologies in medicinal Physalis plants in recent years was reviewed, in order to provide an important molecular technical basis for the identification, classification and rational development and protection of medicinal Physalis resources.

Succinyl-proteome profiling of Dendrobium officinale, an important traditional Chinese orchid herb, revealed involvement of succinylation in the glycolysis pathway.

BACKGROUND: Lysine succinylation is a ubiquitous and important protein post-translational modification in various eukaryotic and prokaryotic cells. However, its functions in Dendrobium officinale, an important traditional Chinese orchid herb with high polysaccharide contents, are largely unknown. RESULTS: In our study, LC-MS/MS was used to identify the peptides that were enriched by immune-purification with a high-efficiency succinyl-lysine antibody. In total, 314 lysine succinylation sites in 207 proteins were identified. A gene ontology analysis showed that these proteins are associated with a wide range of cellular functions, from metabolic processes to stimuli responses. Moreover, two types of conserved succinylation motifs, '***Ksuc******K**' and '****EKsuc***', were identified. Our data showed that lysine succinylation occurred on five key enzymes in the glycolysis pathway. The numbers of average succinylation sites on these five enzymes in plants were lower than those in bacteria and mammals. Interestingly, two active site amino acids residues, K103 and K225, could be succinylated in fructose-bisphosphate aldolase, indicating a potential function of lysine succinylation in the regulation of glycolytic enzyme activities. Furthermore, the protein-protein interaction network for the succinylated proteins showed that several functional terms, such as glycolysis, TCA cycle, oxidative phosphorylation and ribosome, are consisted. CONCLUSIONS: Our results provide the first comprehensive view of the succinylome of D. officinale and may accelerate future biological investigations of succinylation in the synthesis of polysaccharides, which are major active ingredients.

Genome-wide analysis and characterization of Aux/IAA family genes related to fruit ripening in papaya (Carica papaya L.).

BACKGROUND: Auxin/indole-3-acetic acid (Aux/IAA) family genes encode short-lived nuclear proteins that mediate the responses of auxin-related genes and are involved in several plant developmental and growth processes. However, how Aux/IAA genes function in the fruit development and ripening of papaya (Carica papaya L.) is largely unknown. RESULTS: In this study, a comprehensive identification and a distinctive expression analysis of 18 C. papaya Aux/IAA (CpIAA) genes were performed using newly updated papaya reference genome data. The Aux/IAA gene family in papaya is slightly smaller than that in Arabidopsis, but all of the phylogenetic subfamilies are represented. Most of the CpIAA genes are responsive to various phytohormones and expressed in a tissues-specific manner. To understand the putative biological functions of the CpIAA genes involved in fruit development and ripening, quantitative real-time PCR was used to test the expression profiling of CpIAA genes at different stages. Furthermore, an IAA treatment significantly delayed the ripening process in papaya fruit at the early stages. The expression changes of CpIAA genes in ACC and 1-MCP treatments suggested a crosstalk between auxin and ethylene during the fruit ripening process of papaya. CONCLUSIONS: Our study provided comprehensive information on the Aux/IAA family in papaya, including gene structures, phylogenetic relationships and expression profiles. The involvement of CpIAA gene expression changes in fruit development and ripening gives us an opportunity to understand the roles of auxin signaling in the maturation of papaya reproductive organs.

Comparative proteomic analyses of two Taxus species (Taxus × media and Taxus mairei) reveals variations in the metabolisms associated with paclitaxel and other metabolites.

Taxus species are well-known for paclitaxel, which exhibits antitumor activities and is used for treating various cancers. Although most Taxus species are widespread in many areas, few studies have characterized the variation in metabolism among different Taxus species. Using an integrated approach involving 'tandem mass tag' labeling and liquid chromatography-tandem mass spectrometry (HPLC-MS), proteomes of T. media and T. mairei were investigated and 4078 proteins were quantified. Screening and classification of differentially expressed proteins revealed many metabolism-associated proteins. In detail, four enzymes involved in the flavonoid biosynthesis pathway were predominantly expressed in T. mairei. Four enzymes associated with supplying precursors for paclitaxel biosynthesis and three cytochrome P450 taxoid oxygenases were preferentially expressed in T. media compared with T. mairei. Furthermore, variations in taxoid contents between T. media and T. mairei were determined using HPLC-MS analysis. Variations in flavonoid contents between T. media and T. mairei were determined by HPLC analysis. A number of differentially expressed proteins may provide an explanation for the variation in metabolisms of different Taxus species.

Comparative transcriptomic analyses of normal and malformed flowers in sugar apple (Annona squamosa L.) to identify the differential expressed genes between normal and malformed flowers.

BACKGROUND: Sugar apple (Annona squamosa L.), a popular fruit with high medicinal and nutritional properties, is widely cultivated in tropical South Asia and America. The malformed flower is a major cause for a reduction in production of sugar apple. However, little information is available on the differences between normal and malformed flowers of sugar apple. RESULTS: To gain a comprehensive perspective on the differences between normal and malformed flowers of sugar apple, cDNA libraries from normal and malformation flowers were prepared independently for Illumina sequencing. The data generated a total of 70,189,896 reads that were integrated and assembled into 55,097 unigenes with a mean length of 783 bp. A large number of differentially expressed genes (DEGs) were identified. Among these DEGs, 701 flower development-associated transcript factor encoding genes were included. Furthermore, a large number of flowering- and hormone-related DEGs were also identified, and most of these genes were down-regulated expressed in the malformation flowers. The expression levels of 15 selected genes were validated using quantitative-PCR. The contents of several endogenous hormones were measured. The malformed flowers displayed lower endogenous hormone levels compared to the normal flowers. CONCLUSIONS: The expression data as well as hormone levels in our study will serve as a comprehensive resource for investigating the regulation mechanism involved in floral organ development in sugar apple.