CbMYB108 integrates the regulation of diterpene biosynthesis and trichome development in Conyza blinii against UV-B.

Plants synthesize abundant terpenes through glandular trichomes (GTs), thereby protecting themselves from environmental stresses and increasing the economic value in some medicinal plants. However, the potential mechanisms for simultaneously regulating terpenes synthesis and GTs development remain unclear. Here, we showed that terpenes in Conyza blinii could be synthesized through capitate GTs. By treating with appropriate intensity of UV-B, the density of capitate GTs and diterpene content can be increased. Through analyzing corresponding transcriptome, we identified a MYB transcription factor CbMYB108 as a positive regulator of both diterpene synthesis and capitate GT density. Transiently overexpressing/silencing CbMYB108 on C. blinii leaves could increase diterpene synthesis and capitate GT density. Further verification showed that CbMYB108 upregulated CbDXS and CbGGPPS expression in diterpene synthesis pathway. Moreover, CbMYB108 could also upregulated the expression of CbTTG1, key WD40 protein confirmed in this study to promote GT development, rather than through interaction between CbMYB108 and CbTTG1 proteins. Thus, results showed that the UV-B-induced CbMYB108 owned dual-function of simultaneously improving diterpene synthesis and GT development. Our research lays a theoretical foundation for cultivating C. blinii with high terpene content, and broadens the understanding of the integrated mechanism on terpene synthesis and GT development in plants.

Conyza canadensis from Jordan: Phytochemical Profiling, Antioxidant, and Antimicrobial Activity Evaluation.

In this investigation, the chemical composition of the hydro-distilled essential oil (HD-EO), obtained from the fresh aerial parts (inflorescence heads (Inf), leaves (L), and stems (St)) of Conyza canadensis growing wild in Jordan was determined by GC/MS. Additionally, the methanolic extract obtained from the whole aerial parts of C. canadensis (CCM) was examined for its total phenolic content (TPC), total flavonoids content (TFC), DPPH radical scavenging activity, iron chelating activity and was then analyzed with LC-MS/MS for the presence of certain selected phenolic compounds and flavonoids. The GC/MS analysis of CCHD-EOs obtained from the different aerial parts revealed the presence of (2E, 8Z)-matricaria ester as the main component, amounting to 15.4% (Inf), 60.7% (L), and 31.6% (St) of the total content. Oxygenated monoterpenes were the main class of volatile compounds detected in the Inf-CCHD-EO. However, oils obtained from the leaves and stems were rich in polyacetylene derivatives. The evaluation of the CCM extract showed a richness in phenolic content (95.59 ± 0.40 mg GAE/g extract), flavonoids contents (467.0 ± 10.5 mg QE/ g extract), moderate DPPH radical scavenging power (IC50 of 23.75 ± 0.86 µg/mL) and low iron chelating activity (IC50 = 5396.07 ± 15.05 µg/mL). The LC-MS/MS profiling of the CCM extract allowed for the detection of twenty-five phenolic compounds and flavonoids. Results revealed that the CCM extract contained high concentration levels of rosmarinic acid (1441.1 mg/kg plant), in addition to caffeic acid phenethyl ester (231.8 mg/kg plant). An antimicrobial activity assessment of the CCM extract against a set of Gram-positive and Gram-negative bacteria, in addition to two other fungal species including Candida and Cryptococcus, showed significant antibacterial activity of the extract against S. aureus with MIC value of 3.125 µg/mL. The current study is the first phytochemical screening for the essential oil and methanolic extract composition of C. canadensis growing in Jordan, its antioxidant and antimicrobial activity.

The Blinin Accumulation Promoted by CbMYB32 Involved in Conyza blinii Resistance to Nocturnal Low Temperature.

Blinin, a unique terpenoid from Conyza blinii (C. blinii), benefits our health even though this is not its primary function. Physiological and ecological studies have found that the great secondary metabolites participate in important biological processes and relate to species evolution, environmental adaptation, and so on. Moreover, our previous studies have shown that the metabolism and accumulation of blinin has a close correspondence with nocturnal low temperature (NLT). To find out the transcriptional regulation linker in the crosstalk between blinin and NLT, RNA-seq, comparative analysis, and co-expression network were performed. The results indicated that CbMYB32 is located in a nucleus without independent transcriptional activation activity and is probably involved in the metabolism of blinin. Furthermore, we compared the silence and overexpression of CbMYB32 with wild C. blinii. Compared with the overexpression and the wildtype, the CbMYB32 silence line lost more than half of the blinin and detected more peroxide under NLT. Finally, as a characteristic secret of C. blinii, it is reasonable to infer that blinin participates in the NLT adaptation mechanism and has contributed to the systematic evolution of C. blinii.

The role of the antioxidant system and the photosynthetic behavior of paraquat-resistant Conyza sumatrensis in Brazil.

Greenhouse experiments were carried out aiming to characterize-morphologically and biochemically-resistant and susceptible plants of C. sumatrensis. Two experiments were carried out to evaluate the behavior of morphological variables such as leaf area, height, and dry biomass weight, without application of paraquat (1,1'-dimethyl-4,4'-bipyridinium dichloride). Other experiments were conducted with two rates of paraquat application (0 and 800 g a.i ha-1); physiological variables were assessed at 2, 4, and 24 h after application (HAA), and plants were collected at 4 HAA for biochemical analyses of antioxidant enzymes and cell membrane peroxidation level. Without herbicide application, paraquat-resistant populations had higher dry biomass, leaf area, liquid photosynthetic rate, carboxylation efficiency, and stomatal conductance. The recovery of the photosynthetic apparatus by resistant plants after paraquat application is rapid (16 HAA) and, in general, presents physiological improvements in terms of photosynthetic rate and carboxylation efficiency. After paraquat treatment, the antioxidant system enzymes of resistant plants showed increased activity and decreased membrane peroxidation, indicating that these enzymes play an important role in the resistance mechanism of these plants.

Antifungal effects of Conyza bonariensis (L.) Cronquist essential oil against pathogenic Colletotrichum musae and its incorporation in gum Arabic coating to reduce anthracnose development in banana during storage.

AIM: This study evaluated the inhibitory effects on mycelial growth and damage on membrane integrity and enzymatic activity caused by Conyza bonariensis essential oil (CBEO) on distinct pathogenic Colletotrichum musae isolates, as well as the preventive and curative effects of coatings with gum Arabic (GA) and CBEO to reduce anthracnose development in banana during room temperature storage. The effects of GA-CBEO coatings on some physicochemical parameters of banana were investigated during room temperature storage. METHOD AND RESULTS: CBEO (0.4-1 µl ml-1 ) inhibited the mycelial growth of C. musae isolates in laboratory media. The exposure of C. musae conidia to CBEO (0.6 µl ml-1 ) for 3 and 5 days resulted in high percentages of conidia with damaged cytoplasmic membrane and without enzymatic activity. Coatings with GA (0.1 mg ml-1 ) and CBEO (0.4-1 µl ml-1 ) reduced the anthracnose development in banana artificially contaminated with C. musae during storage. In most cases, the disease severity indexes found for GA-CBEO-coated banana were lower than or similar to those for banana treated with commercial fungicide. GA-CBEO-coated banana had reduced alterations in physicochemical parameters during storage, indicating more prolonged storability. CONCLUSION: The application of GA-CBEO coatings is effective to delay the anthracnose development in banana during storage, which should help to reduce the amount of fungicides used to control postharvest diseases in this fruit. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study showing the efficacy of coatings formulated with GA and CBEO to delay the development of anthracnose in banana, as well as to decrease alterations in physicochemical parameters indicative of postharvest quality of this fruit during storage. In a practical point of view, GA-CBEO coatings could be innovative strategies to delay the anthracnose development and postharvest losses in banana.

Transcriptome profiling of Arabidopsis thaliana roots in response to allelopathic effects of Conyza canadensis.

The molecular mechanisms underlying allelopathy and their role in the interactions between invasive weeds and native species remain unclear. In this study, we aimed to explore the physiological and molecular response of plant roots of a native species to allelopathy from an invasive weed. We examined the growth and development of roots of native Arabidopsis thaliana for a 2-week period after being treated with aqueous extracts at different concentrations from invasive Conyza canadensis. Extracts with higher concentration in the Murashige and Skoog (MS) media (i.e., 4 mg of extract/mL of MS) significantly affected the root growth of A. thaliana. Roots of A. thaliana displayed weakened root tip activity and an accumulation of reactive oxygen species (ROS) in response to extracts from C. canadensis. The transcriptome analysis of A. thaliana roots exposed to phytotoxicity revealed differentially expressed genes (DEGs) involved in cell wall formation, abiotic stress, transporter genes and signal transduction. We found that genes associated with nutrient transport, such as major facilitator superfamily (MFS) and amino acid permease (AAP3) transporters as well as genes involved in stress response, including leucine-rich repeat receptor-like protein kinases (LRR-RLKs) were down-regulated. In addition, we found that many transcription factors associated with plant stress (such as APETALA2/ethylene response factors) were up-regulated while others (e.g., zinc-finger proteins) were down-regulated. Allelochemicals from C. canadensis also induced the up-regulation of detoxification (DTX) genes, ROS related genes, calcineurin B-like interacting protein kinases (CIPKs) and calmodulin. Overall, our findings provided insights into allelopathy in C. canadensis at the molecular level, and contributes to our understanding of invasion mechanisms of alien plant species. CLINICAL TRIALS REGISTRATION: This study does not contain any studies with clinical trials performed by any of the authors.

Characterization of Conyza bonariensis Allelochemicals against Broomrape Weeds.

The study of allelopathic activity of plants and the isolation and characterization of the responsible allelochemicals can lead to the development of environment friendly alternative approaches to weed control. Conyza species are invasive weeds that use allelopathic activity as part of a successful strategy to outcompete neighboring plants. Broomrape weeds are parasitic plants that use host-induced germination and the formation of a haustorium as strategies to infect host plants. The control of broomrape infection in most affected crops is limited or non-existing. In the current study, we investigated the allelopathic activity of Conyza bonariensis organic extracts in suicidal germination and radicle growth of four broomrape species (Orobanche crenata, Orobanche cumana, Orobanche minor and Phelipanche ramosa). A bioactivity-driven fractionation of Conyza bonariensis extracts led to the identification of two germination-inducing molecules and two growth-inhibitory compounds. The germination-inducing metabolites had species-specific activity being hispidulin active on seeds of O. cumana and methyl 4-hydroxybenzoate active in P. ramosa. The growth-inhibitory metabolites (4Z)-lachnophyllum lactone and (4Z,8Z)-matricaria lactone strongly inhibited the radicle growth of all parasitic weed species studied. Some structure-activity relationships were found as result of the study herein presented.

Phytochemical Profiles, Antioxidant, Cytotoxic, and Anti-Inflammatory Activities of Traditional Medicinal Plants: Centaurea pichleri subsp. pichleri, Conyza canadensis, and Jasminum fruticans.

Centaurea pichleri subsp. pichleri, Conyza canadensis, and Jasminum fruticans are traditionally used plants grown in Turkey. Methanol extracts were obtained from these plants and pharmacological activity studies and phytochemical analyses were carried out. To evaluate the phytochemical composition, spectrophotometric and chromatographic techniques were used. The extracts were evaluated for antioxidant activity by DPPH●, ABTS●+ radical scavenging, and FRAP assays. The cytotoxic effects of the extracts were investigated on DU145 prostate cancer and A549 lung cancer cell lines. The anti-inflammatory effects of extracts were investigated on the NO amount, TNF-α, IFN-γ, and PGE 2 levels in lipopolysaccharide-stimulated Raw 264.7 cells. The richest extract in terms of phenolic compounds (98.19 ± 1.64 mgGAE/gextract) and total flavonoids (21.85 ± 0.64 mgCA/gextract) was identified as C. pichleri subsp. pichleri methanol extract. According to antioxidant activity determinations, the C. pichleri subsp. pichleri extract was found to be the most active extract. Finally, the C. pichleri subsp. pichleri methanol extract was revealed to be the most effective inhibitor of viability in the cytotoxic activity investigation, and the extract with the best anti-inflammatory action. The findings point to C. pichleri subsp. pichleri as a promising source of bioactive compounds in the transition from natural sources to industrial uses, such as new medications, cosmeceuticals, and nutraceuticals.

Vasorelaxant Mechanism of Herbal Extracts from Mentha suaveolens, Conyza canadensis, Teucrium polium and Salvia verbenaca in the Aorta of Wistar Rats.

Mentha suaveolens (MS), Conyza canadensis (CC), Teucrium polium (TP) and Salvia verbenaca (SV) are used in Morocco to treat hypertension. Our aim was to characterize the composition and vasoreactivity of extracts of MS, CC, TP and SV. The chemical compositions of aqueous extracts of MS, SV and TP, and of a hydromethanolic extract of CC, were identified by HPLC-DAD. The vasoreactive effect was tested in rings of the thoracic aorta of female Wistar rats (8-14 weeks-old) pre-contracted with 10 µM noradrenaline, in the absence or presence of L-NAME 100 µM, indomethacin 10 µM or atropine 6 µM, to inhibit nitric oxide synthase, cyclooxygenase or muscarinic receptors, respectively. L-NAME and atropine decreased the vasorelaxant effect caused by low concentrations of MS. Atropine and indomethacin decreased the vasorelaxant effect of low concentrations of SV. High concentrations of MS or SV and the effect of SV and TP were not altered by any antagonist. The activation of muscarinic receptors and NO or the cyclooxygenase pathway underlie the vasorelaxant effect of MS and SV, respectively. Neither of those mechanisms underlines the vasorelaxant effect of CC and TP. These vasorelaxant effect might support the use of herbal teas from these plants as anti-hypertensives in folk medicine.

Conyza bonariensis as an alternative host for Colletotrichum species in Argentina.

AIMS: This study investigated the diversity of Colletotrichum isolates recovered from Conyza bonariensis leaves through the use of morphological characteristics, growth rate, carbon sources utilization and phylogenetic analysis. METHODS AND RESULTS: In all, 30 Colletotrichum isolates recovered from C. bonariensis leaves showing symptoms of disease were included in the present study. Based on the analysis of morphology and sequences, the isolates were distributed into six Colletotrichum species complexes. The concatenated alignment of GAPDH and ITS sequences showed that 20 out of 30 isolates were included in four species complexes which comprise the most important pathogens causing anthracnose in soybean or anthracnose and stalk rot in maize: C. truncatum, C. orchidearum, C. gloeosporioides and C. graminicola. The remaining 10 isolates were included in the C. boninense and C. destructivum species complexes or could not be assigned to any complex with the available information. CONCLUSION: Weeds belonging to genus Conyza are host to soybean and maize potential pathogenic species of Colletotrichum and could have a role as inoculum reservoir for cross contamination in the agroecosystem. SIGNIFICANCE AND IMPACT OF THE STUDY: The combined use of morphological, kinetics and physiological parameters of growth and phylogenetic analysis in Colletotrichum isolates from Conyza leaves allowed the detection of species complexes previously not identified in Argentina.

Monitoring Glyphosate- and Chlorimuron- resistant Conyza spp. Populations in Brazil.

Conyza species are important weeds in global agriculture, especially due to their capacity to evolve resistance to multiple herbicide mechanisms of action. We aimed to evaluate the frequency and distribution of resistance to glyphosate and chlorimuron-ethyl in Conyza spp. populations from Brazil. Seed samples were collected from grain production areas across nine Brazilian states over five consecutive years (2014 to 2018). Prior to resistance monitoring trials, dose-response assays were conducted to determine a single dose of glyphosate or chlorimuron-ethyl to discriminate resistant and susceptible populations. Resistance monitoring based on plant responses to the application of discriminatory doses of glyphosate (960 g ha-1) or chlorimuron-ethyl (20 g ha-1). Populations were classified as resistant, moderately resistant, or susceptible to either herbicide. While glyphosate resistance was highly frequent (71.2%) in all the five years, chlorimuron-ethyl resistant populations occurred at 39.8% of the total. The frequency of multiple resistance to both herbicides (35.3%) was proportional to the occurrence of chlorimuron-ethyl resistance (39.6%). Resistance to glyphosate and to chlorimuron-ethyl were found across all states evaluated.

Pharmacological, Phytochemical and histopathological basis of Conyza bonariensis in the potential management of diabetes mellitus.

To evaluate the anti-diabetic potential of aqueous methanolic extract of Conyza bonariensis amongst the Wistar rats. Phytochemical and High Performance Liquid Chromatography (HPLC) analyses of phenols and flavonoids were examined. The plant extract (250 and 500mg/kg/day) was explored for its anti-hyperglycemic effect for 14 days in normoglycemic and alloxan-induced diabetic rats using the oral glucose tolerance test (OGTT). HPLC analyses demonstrated the composition of the plant extract as gallic acid, cinnamic acid, quercetin, p-coumaric acid and syringic acid. The blood glucose concentrations in experimental diabetic as well as non-diabetic rats significantly decreased with doses 250 and 500 mg/kg in OGTT. Moreover, the significant drop in fasting glucose level was observed following 14 days of therapy. It also ameliorated the serum cholesterol, total protein, low and high density lipoproteins, glycosylated hemoglobin A1C and serum amylase with respect to untreated rats suffering from diabetes. There appeared to be no significant alteration with regard to body weight amongst the treated rats. The plant extract revamped the pancreatic islets of Langerhans and abridged alloxan-induced degenerative changes in the liver. It can be concluded that Conyza bonariensis extract has a pronounced hypoglycemic effect on diabetes due to the presence of phytochemicals.

Ferrous iron-induced increases in capitate glandular trichome density and upregulation of CbHO-1 contributes to increases in blinin content in Conyza blinii.

MAIN CONCLUSION: Ferrous iron can promote the development of glandular trichomes and increase the content of blinin, which depends on CbHO-1 expression. Conyza blinii (C. blinii) is a unique Chinese herbal medicine that grows in Sichuan Province, China. Because the habitat of C. blinii is an iron ore mining area with abundant iron content, this species can be used as one of the best materials to study the mechanism of plant tolerance to iron. In this study, C. blinii was treated with ferrous-EDTA solutions at different concentrations, and it was found that the tolerance value of C. blinii to iron was 200 µM. Under this concentration, the plant height, root length, biomass, and iron content of C. blinii increased to the maximum values, and the effect was dependent on the upregulated expression of CbHO-1. At the same time, under ferrous iron, the photosynthetic capacity and capitate glandular trichome density of C. blinii also significantly increased, providing precursors and sites for the synthesis of blinin, thus significantly increasing the content of blinin. These processes were also dependent on the high expression of CbHO-1. Correlation analysis showed that there were strong positive correlations between iron content, capitate glandular trichome density, CbHO-1 gene expression, and blinin content. This study explored the effects of ferrous iron on the physiology and biochemistry of C. blinii, greatly improving our understanding of the mechanism of iron tolerance in C. blinii.

Using Apache Spark on genome assembly for scalable overlap-graph reduction.

BACKGROUND: De novo genome assembly is a technique that builds the genome of a specimen using overlaps of genomic fragments without additional work with reference sequence. Sequence fragments (called reads) are assembled as contigs and scaffolds by the overlaps. The quality of the de novo assembly depends on the length and continuity of the assembly. To enable faster and more accurate assembly of species, existing sequencing techniques have been proposed, for example, high-throughput next-generation sequencing and long-reads-producing third-generation sequencing. However, these techniques require a large amounts of computer memory when very huge-size overlap graphs are resolved. Also, it is challenging for parallel computation. RESULTS: To address the limitations, we propose an innovative algorithmic approach, called Scalable Overlap-graph Reduction Algorithms (SORA). SORA is an algorithm package that performs string graph reduction algorithms by Apache Spark. The SORA's implementations are designed to execute de novo genome assembly on either a single machine or a distributed computing platform. SORA efficiently compacts the number of edges on enormous graphing paths by adapting scalable features of graph processing libraries provided by Apache Spark, GraphX and GraphFrames. CONCLUSIONS: We shared the algorithms and the experimental results at our project website, https://github.com/BioHPC/SORA . We evaluated SORA with the human genome samples. First, it processed a nearly one billion edge graph on a distributed cloud cluster. Second, it processed mid-to-small size graphs on a single workstation within a short time frame. Overall, SORA achieved the linear-scaling simulations for the increased computing instances.

Spiroconyone A, a new phytosterol with a spiro [5,6] ring system from Conyza japonica.

Spiroconyone A (1), the first rearranged phytosterol featuring an unusual spiro [5,6] ring system, and nine known compounds (2-10) were isolated from the aerial parts of Conyza japonica. The structure of 1 was elucidated through spectroscopic methods, and its absolute configuration was determined by single-crystal X-ray diffraction analysis. Enzyme-based assay revealed that spiroconyone A showed weak TDP1 inhibition and compounds 7 and 10 showed TDP1 inhibition with IC50 values of 36 µM and 16 µM, respectively. MTT assay indicated that 7 and 10 showed a strong synergistic effect with the clinical TOP1 inhibitor topotecan in MCF-7 cells. Compound 5 displayed the most potent cytotoxicity against MCF-7 cells with a GI50 value of 3.3 µM. Furthermore, a hypothetical biosynthetic pathway for 1 was proposed. This work provides valuable information that the secondary metabolites from Conyza japonica could be developed as anticancer agents.

Essential Oil Compositions of Three Invasive Conyza Species Collected in Vietnam and Their Larvicidal Activities against Aedes aegypti, Aedes albopictus, and Culex quinquefasciatus.

Mosquito-borne infectious diseases are a persistent problem in tropical regions of the world, including Southeast Asia. Vector control has relied principally on synthetic insecticides, but these have detrimental environmental effects and there is an increasing demand for plant-based agents to control insect pests. Invasive weedy plant species may be able to serve as readily available sources of essential oils, some of which may be useful as larvicidal agents for control of mosquito populations. We hypothesize that members of the genus Conyza (Asteraceae) may produce essential oils that may have mosquito larvicidal properties. The essential oils from the aerial parts of Conyza bonariensis, C. canadensis, and C. sumatrensis were obtained by hydrodistillation, analyzed by gas chromatography-mass spectrometry, and screened for mosquito larvicidal activity against Aedes aegypti, Ae. albopictus and Culex quinquefasciatus. The essential oils of C. canadensis and C. sumatrensis, both rich in limonene (41.5% and 25.5%, respectively), showed notable larvicidal activities against Ae. aegypti (24-h LC50 = 9.80 and 21.7 µg/mL, respectively) and Ae. albopictus (24-h LC50 = 18.0 and 19.1 µg/mL, respectively). These two Conyza species may, therefore, serve as sources for alternative, environmentally-benign larvicidal control agents.

Purification and Biochemical Characterization of a New Protease Inhibitor from Conyza dioscoridis with Antimicrobial, Antifungal and Cytotoxic Effects.

The main objective of the current study was the extraction, purification, and biochemical characterization of a protein protease inhibitor from Conyzadioscoridis. Antimicrobial potential and cytotoxic effects were also examined. The protease inhibitor was extracted in 0.1 M phosphate buffer (pH 6-7). Then, the protease inhibitor, named PDInhibitor, was purified using ammonium sulfate precipitation followed by filtration through a Sephadex G-50 column and had an apparent molecular weight of 25 kDa. The N-terminal sequence of PDInhibitor showed a high level of identity with those of the Kunitz family. PDInhibitor was found to be active at pH values ranging from 5.0 to 11.0, with maximal activity at pH 9.0. It was also fully active at 50 °C and maintained 90% of its stability at over 55 °C. The thermostability of the PDInhibitor was clearly enhanced by CaCl2 and sorbitol, whereas the presence of Ca2+ and Zn2+ ions, Sodium taurodeoxycholate (NaTDC), Sodium dodecyl sulfate (SDS), Dithiothreitol (DTT), and ß-ME dramatically improved the inhibitory activity. A remarkable affinity of the protease inhibitor with available important therapeutic proteases (elastase and trypsin) was observed. PDInhibitor also acted as a potent inhibitor of commercial proteases from Aspergillus oryzae and of Proteinase K. The inhibitor displayed potent antimicrobial activity against gram+ and gram- bacteria and against fungal strains. Interestingly, PDInhibitor affected several human cancer cell lines, namely HCT-116, MDA-MB-231, and Lovo. Thus, it can be considered a potentially powerful therapeutic agent.

[CbCYP716A261, a New ß-Amyrin 28-Hydroxylase Involved in Conyzasaponin Biosynthesis from Conyza blinii].

Conyzasaponins produced by the traditional Chinese herb Conyza blinii are oleanane-type saponins with a wide range of biological activities. Here, we identified a gene, designated CbCYP716A261, encoding a ß-amyrin 28-hydroxylase in conyzasaponins biosynthesis. Ten full putative CYP sequences were isolated from Conyza blinii transcript tags. The CbCYP716A261 gene product was selected as the putative ß-amyrin 28-hydroxylase by phylogenetic analysis and transcriptional activity analysis of methyl jasmonate-treated Conyza blinii. To identify the enzymatic activity, we performed enzymatic activity experiments in vitro and in vivo. The HPLC results revealed that CbCYP716A261 catalyzes the hydroxylation of ß-amyrin at the C-28 position to yield oleanolic acid. Our findings provide new information about the conyzasaponin biosynthesis pathway and widen the list of isolated ß-amyrin 28-hydroxylases.

Proteomic Analysis of Horseweed (Conyza canadensis) Subjected to Caprylic Acid Stress.

Caprylic acid (CAP) is anticipated to be a potential biocontrol herbicide in the control of weeds, however the molecular mechanism of how CAP affects weeds is poorly understood. Here, the physiological and biochemical (protein-level) changes in horseweed (Conyza canadensis L.) are studied under CAP treatment, with infrared gas analyzer and label-free quantitative proteomics methods. In total, 112 differentially-accumulated proteins (DAPs) (>1.5 fold change, p < 0.05) are present between treated horseweed and control samples, with 46 up-regulated and 66 down-regulated proteins. These DAPs are involved in 28 biochemical pathways, including photosynthesis pathways. In particular, six photosynthesis proteins show significant abundance changes in the CAP-treated horseweed. The qRT-PCR results confirm three of the six genes involved in photosynthesis. Moreover, by measuring photosynthesis characteristics, CAP was shown to decrease photosynthetic rate, stomatal conductance, intercellular CO2 concentration, and the transpiration rate of horseweed. These results suggest that photosystem I is one of the main biological processes involved in the response of horseweed to CAP.

Investigation of glyphosate resistance levels and target-site based resistance (TSR) mechanisms in Conyza canadensis (L.) from apple orchards around areas of Bohai seas and Loess Plateau in China.

The resistance levels to glyphosate and target-site based resistance mechanisms in susceptible (S) and resistant (R) Conyza canadensis (L.) populations, which were collected from apple orchards around areas of Bohai seas and Loess Plateau in China, were investigated. Among forty C. canadensis populations, eighteen populations (45%) were still susceptible; fourteen populations (35%) evolved low resistance levels resistance to glyphosate with resistance index (RI) of 2.02 to 3.90. In contrast, eight populations (20%) evolved medium resistance levels with RI of 4.35 to 8.38. The shikimic acid concentrations in R populations were highly negative relative with the glyphosate resistance levels in C. canadensis, the Pearson correlation coefficient was -0.82 treated by glyphosate at 1.8mg/L. Three 5-enoylpyruvylshikimate 3'-phosphate synthase genes (EPSPS1, EPSPS2 and EPSPS3) were cloned in all S and glyphosate-resistant C. canadensis populations. No amino acid substitution was identified at site of 102 and 106 in three EPSPS genes, which were reported to confer glyphosate resistance in other weed species. The relative expression level of EPSPS mRNA in R populations (SD07, LN05, SHX06 and SD09) was 4.5 to 13.2 times higher than in S biotype. The Pearson correlation coefficient between EPSPS expression levels and RI was 0.79, which indicated the over expression of EPSPS mRNA may cause these R populations evolve higher resistance level to glyphosate.