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Isoflavones belong to the class of flavonoid compounds, which are important secondary metabolites that play a crucial role in plant development and defense. Acetyl-CoA carboxylase (ACCase) is a biotin-dependent enzyme that catalyzes the conversion of Acetyl-CoA into Malonyl-CoA in plants. It is a key enzyme in fatty acid synthesis and also catalyzes the production of various secondary metabolites. However, information on the ACC gene family in the soybean (Glycine max L. Merr.) genome and the specific members involved in isoflavone biosynthesis is still lacking. In this study, we identified 20 ACC family genes (GmACCs) from the soybean genome and further characterized their evolutionary relationships and expression patterns. Phylogenetic analysis showed that the GmACCs could be divided into five groups, and the gene structures within the same groups were highly conserved, indicating that they had similar functions. The GmACCs were randomly distributed across 12 chromosomes, and collinearity analysis suggested that many GmACCs originated from tandem and segmental duplications, with these genes being under purifying selection. In addition, gene expression pattern analysis indicated that there was functional divergence among GmACCs in different tissues. The GmACCs reached their peak expression levels during the early or middle stages of seed development. Based on the transcriptome and isoflavone content data, a weighted gene co-expression network was constructed, and three candidate genes (Glyma.06G105900, Glyma.13G363500, and Glyma.13G057400) that may positively regulate isoflavone content were identified. These results provide valuable information for the further functional characterization and application of GmACCs in isoflavone biosynthesis in soybean. [ABSTRACT FROM AUTHOR]

Isoflavones belong to the class of flavonoid compounds, which are important secondary metabolites that play a crucial role in plant development and defense. Acetyl-CoA carboxylase (ACCase) is a biotin-dependent enzyme that catalyzes the conversion of Acetyl-CoA into Malonyl-CoA in plants. It is a key enzyme in fatty acid synthesis and also catalyzes the production of various secondary metabolites. However, information on the ACC gene family in the soybean (Glycine max L. Merr.) genome and the specific members involved in isoflavone biosynthesis is still lacking. In this study, we identified 20 ACC family genes (GmACCs) from the soybean genome and further characterized their evolutionary relationships and expression patterns. Phylogenetic analysis showed that the GmACCs could be divided into five groups, and the gene structures within the same groups were highly conserved, indicating that they had similar functions. The GmACCs were randomly distributed across 12 chromosomes, and collinearity analysis suggested that many GmACCs originated from tandem and segmental duplications, with these genes being under purifying selection. In addition, gene expression pattern analysis indicated that there was functional divergence among GmACCs in different tissues. The GmACCs reached their peak expression levels during the early or middle stages of seed development. Based on the transcriptome and isoflavone content data, a weighted gene co-expression network was constructed, and three candidate genes (Glyma.06G105900, Glyma.13G363500, and Glyma.13G057400) that may positively regulate isoflavone content were identified. These results provide valuable information for the further functional characterization and application of GmACCs in isoflavone biosynthesis in soybean.

Acetyl-CoA carboxylase (ACCase: EC 6.4.1.2) is one of the essential biotins containing enzymes required by plants for fatty acid synthesis and elongation. The unique enzyme is present in its homomeric form in all the Gramineae family, making it a suitable target for developing herbicides selectively against weeds of the Gramineae family. One such example is infestation of Phalaris minor in winter wheat crop fields, where aryloxyphenoxypropionates (FOP); cyclohexanediones (DIM) and phenyl pyrazoline (DEN) group of ACCase inhibiting herbicides are used. However, the increasing number of ACCase herbicide resistant weed populations has compelled agro-scientists to seek varied possibilities for weed control, through Integrated Weed Management (IWM) strategies. Developing new potential herbicides to regain sensitivity in weeds could be an approach to weed control. The current advancement in computational techniques could be of aid in developing new herbicide-like molecules by exploring the genomics, proteomics and structural details of catalytic sites of herbicide action in crops as well as weeds.

Asia minor bluegrass (Polypogon fugax) is a common and problematic weed throughout China. P. fugax that is often controlled by acetyl-CoA carboxylase (ACCase) inhibitors in canola fields. Herein, we confirmed a P. fugax population (R) showing resistance to all ACCase inhibitors tested with resistance indexes ranging from 5.4–18.4. We further investigated the resistance mechanisms of this R population. Molecular analyses revealed that an amino acid mutation (Asp-2078-Gly) was present in the R population by comparing ACCase gene sequences of the sensitive population (S). In addition, differences in susceptibility between the R and S population were unlikely to be related to herbicide metabolism. Furthermore, a new derived cleaved amplified polymorphic sequence (dCAPS) method was developed for detecting the Asp-2078-Gly mutation in P. fugax efficiently. We found that 93.75% of plants in the R population carried the Asp-2078-Gly mutation, and all the herbicide-resistant phenotype of this R population is inseparable from this mutation. This is the first report of cross resistance to ACCase inhibitors conferred by the Asp-2078-Gly target-site mutation in P. fugax. The research suggested the urgent need to improve the diversity of weed management practices to prevent the widespread evolution of herbicide resistance in P. fugax in China. [ABSTRACT FROM AUTHOR]

Lolium rigidum Gaud. (rigid ryegrass) is one of the most widespread weeds in cereal crops in Morocco, Algeria and Tunisia. This weed has evolved resistance to various herbicide modes of action in this region. ACCase and ALS inhibiting herbicides are mainly used in the major-cereal growing regions to control rigid ryegrass. Through a questionnaire, regions where farmers reported less control of herbicide treatments were registered in the three Maghreb countries. Registered fields were visited for collection and 75 field populations were screened with two ACCase and two ALS herbicides. Target site resistance (TSR) was diagnosed using Illumina Next Generation Sequencing (NGS) technology. The sensitivity bioassay results revealed over 60% of sampled populations to be resistant to pinoxaden and/or clodinafop and about 40% to be resistant to iodosulfuron + mesosulfuron and/or pyroxsulam. In addition, 53% of populations displayed resistance (R) to the two herbicide modes of action tested among the regions. In total, 16 ACCase and 11 ALS mutant alleles were identified, carrying out an amino-acid substitution and conferring herbicide resistance in 3700 of the analyzed plants. Most ACCase and ALS mutations were detected at codons Ile1781 and Pro197, respectively. Not only does this study demonstrate the presence of both cross and multiple resistance, it also highlights the non-ACCase and non-ALS -based resistance mechanisms that could confer resistance to herbicides with different modes of action which complicates the resistance management strategies. In the three Maghreb countries, this challenge is even more prominent due to few modes of action being available for rigid ryegrass control due to low-cost market and the prevalence of generic herbicides. • ACCase and ALS inhibiting herbicides are failing more and more to control rigid ryegrass. • Resistance of rigid ryegrass to various modes of action is confirmed in the three Maghreb countries Morocco, Tunisia and Algeria. • First broad-scale resistance survey implementing high-throughput genotyping-by-sequencing. • Both cross and multiple resistance as well as the non-ACCase and non-ALS -based resistance mechanisms that could confer resistance to herbicides. • Few modes of action, low-cost market and the prevalence of generic herbicides complicate the resistance management strategies. • Lolium rigidum resistance to ACCase and ALS inhibitors is prevalent throughout the northern Africa region. [ABSTRACT FROM AUTHOR]

Significance Statement: The limiting subunit of plant acetyl‐CoA carboxylase was identified as α‐carboxyltransferase via absolute protein quantification; overexpression of this subunit in Arabidopsis and Camelina led to an increase of both fatty acid synthesis rate and seed oil content. [ABSTRACT FROM AUTHOR]

BACKGROUND Metabolic resistance is a worldwide concern for weed control but has not yet been well‐characterized at the genetic level. Previously, we have identified an Asia minor bluegrass (Polypogon fugax Nees ex Steud.) population AHHY exhibiting cytochrome P450 (P450)‐involved metabolic resistance to fenoxaprop‐P‐ethyl. In this study, we aimed to confirm the metabolic fenoxaprop‐P‐ethyl resistance in AHHY and uncover the potential herbicide metabolism‐related genes in this economically damaging weed species. RESULTS: Liquid chromatography–tandem mass spectrometry (LC–MS/MS) assays indicated the metabolic rates of fenoxaprop‐P‐ethyl were significantly faster in resistant (R, AHHY) than in susceptible (S, SDTS) plants. The amount of phytotoxic fenoxaprop‐P peaked at 12 h after herbicide treatment (HAT) and started to decrease at 24 HAT in both biotypes. R and S plants at 24 HAT were sampled to conduct isoform‐sequencing (Iso‐Seq) and RNA‐sequencing (RNA‐Seq). A reference transcriptome containing 24 972 full‐length isoforms was obtained, of which 24 329 unigenes were successfully annotated. Transcriptomic profiling identified 28 detoxifying enzyme genes constitutively and/or herbicide‐induced up‐regulated in R than in S plants. Real‐time quantitative polymerase chain reaction (RT‐qPCR) confirmed 17 genes were consistently up‐regulated in R and its F1 generation plants. They were selected as potential fenoxaprop‐P‐ethyl metabolism‐related genes, including ten P450s, one glutathione‐S‐transferase, one UDP‐glucosyltransferase, and five adenosine triphosphate (ATP)‐binding cassette transporters. CONCLUSION: This study revealed that the enhanced rates of fenoxaprop‐P‐ethyl metabolism in P. fugax were very likely driven by the herbicide metabolism‐related genes. The transcriptome data generated by Iso‐Seq combined with RNA‐Seq will provide abundant gene resources for understanding the molecular mechanisms of resistance in P. fugax. [ABSTRACT FROM AUTHOR]

Asia minor bluegrass (Polypogon fugax) is a common and problematic weed throughout China. P. fugax that is often controlled by acetyl-CoA carboxylase (ACCase) inhibitors in canola fields. Herein, we confirmed a P. fugax population (R) showing resistance to all ACCase inhibitors tested with resistance indexes ranging from 5.4–18.4. We further investigated the resistance mechanisms of this R population. Molecular analyses revealed that an amino acid mutation (Asp-2078-Gly) was present in the R population by comparing ACCase gene sequences of the sensitive population (S). In addition, differences in susceptibility between the R and S population were unlikely to be related to herbicide metabolism. Furthermore, a new derived cleaved amplified polymorphic sequence (dCAPS) method was developed for detecting the Asp-2078-Gly mutation in P. fugax efficiently. We found that 93.75% of plants in the R population carried the Asp-2078-Gly mutation, and all the herbicide-resistant phenotype of this R population is inseparable from this mutation. This is the first report of cross resistance to ACCase inhibitors conferred by the Asp-2078-Gly target-site mutation in P. fugax. The research suggested the urgent need to improve the diversity of weed management practices to prevent the widespread evolution of herbicide resistance in P. fugax in China.

To explore resistant mechanism of wild oat to fenoxaprop-p-ethyl, the susceptibility of Acetyl-CoA Carboxylase (ACCase) from 24 wild oat populations to fenoxaprop-p-ethyl, the level of gene expression and mutation site of ACCase were conducted. In vitro ACCase activities were solated and measured by enzyme-linked immunosorbent assay kit (ELISA) assays, the results indicated that the IC50 value of the ACCase of the most unsusceptible to fenoxaprop-p-ethyl in the wild oat population from Yexian2017 (\¥24) was 7206.557-fold compared to that of the ACCase of the most susceptible to fenoxaprop-p-ethyl in the wild oat population from Queshan (\Vl 1 ). The level of gene expression of ACCase was significantly higher in the resistant populations than in the relative susceptible populations, and was significantly more suppressed in the relative susceptible populations than in the resistant populations by quantitative Real-time PCR (qPCR). The mutations point of ACCase, Ile-1781-Leu, Trp-1999- Cys, Trp-2027-Cys, Ile-2041-Asn, Asp-2078-Gly, Cys-2088-Arg to have been published were not found in the populations tested by multiple sequence alignment with a model complete ACCase sequence of Alopecurus myosuroides. These findings suggest that ACCase plays a critical role in the development of wild oat resistant mechanism to fenoxaprop-pethyl. [ABSTRACT FROM AUTHOR]

BACKGROUND Asia minor bluegrass (Polypogon fugax Nees ex Steud.) is an invasive grass species severely infesting wheat and canola fields in China. In May 2017, a suspected resistant P. fugax population AHHY that survived fenoxaprop‐P‐ethyl applied at its field‐recommended rate was collected from a wheat field in Huaiyuan County, Anhui Province, China. This study aimed to determine the resistance profile of AHHY to acetyl‐CoA carboxylase (ACCase) inhibitors and to investigate its mechanisms of resistance to fenoxaprop. RESULTS: Single‐dose testing indicated that the AHHY population had evolved resistance to fenoxaprop. The partial carboxyltransferase domain of ACCase in P. fugax was amplified and compared. Four loci encoding plastidic ACCase were isolated from both the resistant and sensitive individuals. Combining gene sequencing with the derived cleaved amplified polymorphic sequence assay, we found that 100% of the plants of AHHY carried Trp‐1999‐Ser mutation in their ACCase1,1–2 allele. Whole‐plant dose–response bioassay indicated that AHHY was highly resistant to fenoxaprop and pinoxaden (resistance index (RI) ≥ 10) with low resistance to clodinafop‐propargyl, sethoxydim, and clethodim (2 ≤ RI < 5). Pre‐treatment with piperonyl butoxide largely reduced (55%) the weed's resistance to fenoxaprop. Both basal and fenoxaprop‐induced glutathione S‐transferases activities toward 1‐chloro‐2, 4‐dinitrobenzene were significantly higher in resistant plants than in susceptible plants. CONCLUSION: This study revealed that P. fugax had multiple alleles encoding plastidic ACCase, and reported for the first time the occurrence of Trp‐1999‐Ser mutation and non‐target‐site resistance in this species. Fenoxaprop resistance in AHHY plants was conferred by target‐site mutation and P450s‐involved enhanced metabolism. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Wild oat (Avena fatua L.) is a common and problematic weed in wheat fields in China. In recent years, farmers found it increasingly difficult to control A. fatua using acetyl-CoA carboxylase (ACCase)-inhibiting herbicides. The purpose of this study was to identify the molecular basis of clodinafop-propargyl resistance in A. fatua. In comparison to the S1496 population, whole dose response studies revealed that the R1623 and R1625 populations were 71.71- and 67.76-fold resistant to clodinafop-propargyl, respectively. The two resistant A. fatua populations displayed high resistance to fenoxaprop-p-ethyl (APP) and low resistance to clethodim (CHD) and pinoxaden (PPZ), but they were still sensitive to the ALS inhibitors mesosulfuron-methyl and pyroxsulam. An Ile-2041-Asn mutation was identified in both resistant individual plants. The copy number and relative expression of the ACCase gene in the resistant population were not significantly different from those in the S1496 population. Under the application of 2160 g ai ha −1 of clodinafop-propargyl, the fresh weight of the R1623 population was reduced to 74.9%; however, pretreatment with the application of the cytochrome P450 inhibitor malathion and the GST inhibitor NBD-Cl reduced the fresh weight to 50.91% and 47.16%, respectively, which proved the presence of metabolic resistance. This is the first report of an Ile-2041-Asn mutation and probable metabolic resistance in A. fatua , resulting in resistance to clodinafop-propargyl. [Display omitted] • Avena fatua L. has evolved high resistance to clodinafop-propargyl in Xinjiang, China. • An Ile-2041-Asn mutation was first identified in resistant A. fatua populations in China. • TSR and NTSR mechanisms were coexisted in resistant A. fatua. [ABSTRACT FROM AUTHOR]

Acetyl-CoA carboxylase (ACCase) is the key regulator of fatty acid biosynthesis. In most plants, ACCase exists in two locations (cytosol and plastids) and in two forms (homomeric and heteromeric). Heteromeric ACCase comprises four subunits, three of them (ACCA–C) are nuclear encoded (nr) and the fourth (ACCD) is usually plastid encoded. Homomeric ACCase is encoded by a single nr-gene (ACC). We investigated the ACCase gene evolution in gymnosperms by examining the transcriptomes of newly sequenced Gnetum ula , combined with 75 transcriptomes and 110 plastomes of other gymnosperms. AccD- coding sequences are elongated through the insertion of repetitive DNA in four out of five cupressophyte families (except Sciadopityaceae) and were functionally transferred to the nucleus of gnetophytes and Sciadopitys. We discovered that, among the three genera of gnetophytes, only Gnetum has two copies of nr- accD. Furthermore, using protoplast transient expression assays, we experimentally verified that the nr- accD precursor proteins in Gnetum and Sciadopitys can be delivered to the plastids. Of the two nr- accD copies of Gnetum , one dually targets plastids and mitochondria, whereas the other potentially targets plastoglobuli. The distinct transit peptides, gene architectures, and flanking sequences between the two Gnetum accD s suggest that they have independent origins. Our findings are the first account of two distinctly targeted nr- accD s of any green plants and the most comprehensive analyses of ACCase evolution in gymnosperms to date. [ABSTRACT FROM AUTHOR]

Abstract: BACKGROUND: Alopecurus japonicus is a serious grass weed species in wheat fields in eastern Asia, and has evolved strong resistance to acetyl‐CoA carboxylase (ACCase)‐inhibiting herbicides. Although target‐site resistance (TSR) to ACCase inhibitors in A. japonicus has been reported, non‐target site resistance (NTSR) has not. This study investigated both TSR and NTSR in a fenoxaprop‐P‐ethyl‐resistant A. japonicus population (AHFD‐3), which was collected in Feidong County, Anhui Province, China. RESULTS: We found that AHFD‐3 exhibited high resistance to fenoxaprop‐P‐ethyl and low resistance to flucarbazone‐sodium. The sensitivity of AHFD‐3 to fenoxaprop‐P‐ethyl increased significantly after treatment with cytochrome P450 (P450) inhibitors; however, such synergies between P450 inhibitors and fenoxaprop‐P‐ethyl were not found in two control populations. Sequences of the entire carboxyltransferase domain of A. japonicus ACCase were obtained, and AHFD‐3 plants showed an Asp‐2078‐Gly substitution in the ACCase. With the derived cleaved amplified polymorphic sequence (dCAPS) method, we found that 85.4% of the plants of AHFD‐3 carried this mutation. The P450 content in AHFD‐3 plants was significantly higher than those of the two control populations after treatment with fenoxaprop‐P‐ethyl. Ten partial sequences of P450 genes in A. japonicus were cloned. Three P450 genes were up‐regulated 12 h after fenoxaprop‐P‐ethyl treatment, which were all from the P450 subfamily CYP72A. Moreover, a P450 gene from the P450 family CYP81 was up‐regulated after fenoxaprop‐P‐ethyl treatment in all populations studied. CONCLUSION: Fenoxaprop‐P‐ethyl resistance in AHFD‐3 plants was conferred by up‐regulation of cytochrome P450s in the CYP72A subfamily and target site mutation of the ACCase gene. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Most methods developed for detecting known single nucleotide polymorphisms (SNP) and deletion−insertion polymorphisms (DIP) are dependent on sequence conservation around the SNP/DIP and are therefore not suitable for application to heterogeneous organisms. Here we describe a novel, versatile and simple PCR-RFLP procedure baptised ‘derived Polymorphic Amplified Cleaved Sequence’ (dPACS) for genotyping individual samples. The notable advantage of the method is that it employs a pair of primers that cover the entire fragment to be amplified except for one or few diagnostic bases around the SNP/DIP being investigated. As such, it provides greater opportunities to introduce mismatches in one or both of the 35−55 bp primers for creating a restriction site that unambiguously differentiates wild from mutant sequences following PCR-RFLP and horizontal MetaPhorTM gel electrophoresis. Selection of effective restriction enzymes and primers is aided by the newly developed dPACS 1.0 software. The highly transferable dPACS procedure is exemplified here with the positive detection (in up to 24 grass and broadleaf species tested) of wild type proline106 of 5-enolpyruvylshikimate-3-phosphate synthase and its serine, threonine and alanine variants that confer resistance to glyphosate, and serine264 and isoleucine2041 which are key target-site determinants for weed sensitivities to some photosystem II and acetyl-CoA carboxylase inhibiting herbicides, respectively.

American sloughgrass ( Beckmannia syzigachne Steud.) is a weed widely distributed in wheat fields of China. In recent years, the evolution of herbicide (fenoxaprop- P -ethyl)-resistant populations has decreased the susceptibility of B. syzigachne . This study compared 4 B. syzigachne populations (3 resistant and 1 susceptible) using iTRAQ to characterize fenoxaprop- P -ethyl resistance in B. syzigachne at the proteomic level. Through searching the UniProt database, 3104 protein species were identified from 13,335 unique peptides. Approximately 2834 protein species were assigned to 23 functional classifications provided by the COG database. Among these, 2299 protein species were assigned to 125 predicted pathways. The resistant biotype contained 8 protein species that changed in abundance relative to the susceptible biotype; they were involved in photosynthesis, oxidative phosphorylation, and fatty acid biosynthesis pathways. In contrast to previous studies comparing only 1 resistant and 1 susceptible population, our use of 3 fenoxaprop-resistant B. syzigachne populations with different genetic backgrounds minimized irrelevant differential expression and eliminated false positives. Therefore, we could more confidently link the differentially expressed proteins to herbicide resistance. Proteomic analysis demonstrated that fenoxaprop- P -ethyl resistance is associated with photosynthetic capacity, a connection that might be related to the target-site mutations in resistant B. syzigachne . This is the first large-scale proteomics study examining herbicide stress responses in different B. syzigachne biotypes. Biological significance This study has biological relevance because it is the first to employ proteomic analysis for understanding the mechanisms underlying Beckmannia syzigachne herbicide resistance. The plant is a major weed in China and negatively affects crop yield, but has developed considerable resistance to the most common herbicide, fenoxaprop- P -ethyl. Through comparisons of resistant and sensitive biotypes, our study identified multiple proteins (involved in photosynthesis, oxidative phosphorylation, and fatty acid biosynthesis) that are putatively linked to B. syzigachne herbicide response. This large-scale proteomics study, sorely lacking in weed science, contributes valuable data that can be applied to more fine-tuned analyses on the functions of specific proteins in herbicide resistance. [ABSTRACT FROM AUTHOR]

Fenoxaprop-P-ethyl-resistant Alopecurus japonicus has become a recurring problem in winter wheat fields in eastern China. Growers have resorted to using mesosulfuron-methyl, an acetolactate synthase (ALS)-inhibiting herbicide, to control this weed. A single A. japonicus population (AH-15) resistant to fenoxaprop-P-ethyl and mesosulfuron-methyl was found in Anhui Province, China. The results of whole-plant dose–response experiments showed that AH-15 has evolved high-level resistance to fenoxaprop-P-ethyl (95.96-fold) and mesosulfuron-methyl (39.87-fold). It was shown via molecular analysis that resistance to both fenoxaprop-P-ethyl and mesosulfuron-methyl was due to an amino acid substitution of Ile1781 to Leu in acetyl-CoA carboxylase (ACCase) and a substitution of Trp 574 to Leu in ALS, respectively. Whole-plant bioassays indicated that the AH-15 population was resistant to the ACCase herbicides clodinafop-propargyl, clethodim, sethoxydim and pinoxaden as well as the ALS herbicides pyroxsulam, flucarbazone-Na and imazethapyr, but susceptible to the ACCase herbicide haloxyfop-R-methyl. This work reports for the first time that A. japonicus has developed resistance to ACCase- and ALS-inhibiting herbicides due to target site mutations in the ACCase and ALS genes. [ABSTRACT FROM AUTHOR]

Asia minor bluegrass ( Polypogon fugax ) is a common and problematic weed throughout China. P. fugax that is often controlled by acetyl-CoA carboxylase (ACCase) inhibitors in canola fields. Herein, we confirmed a P. fugax population (R) showing resistance to all ACCase inhibitors tested with resistance indexes ranging from 5.4-18.4. We further investigated the resistance mechanisms of this R population. Molecular analyses revealed that an amino acid mutation (Asp-2078-Gly) was present in the R population by comparing ACCase gene sequences of the sensitive population (S). In addition, differences in susceptibility between the R and S population were unlikely to be related to herbicide metabolism. Furthermore, a new derived cleaved amplified polymorphic sequence (dCAPS) method was developed for detecting the Asp-2078-Gly mutation in P. fugax efficiently. We found that 93.75% of plants in the R population carried the Asp-2078-Gly mutation, and all the herbicide-resistant phenotype of this R population is inseparable from this mutation. This is the first report of cross resistance to ACCase inhibitors conferred by the Asp-2078-Gly target-site mutation in P. fug ax. The research suggested the urgent need to improve the diversity of weed management practices to prevent the widespread evolution of herbicide resistance in P. fug ax in China.

Abstract: Lipids from microalgae have become a valuable product with applications ranging from biofuels to human nutrition. While changes in fatty acid (FA) content and composition under nitrogen limitation are well documented, the involved molecular mechanisms are poorly understood. Acetyl-CoA carboxylase (ACCase) is a key enzyme in the FA synthesis and elongation pathway. Plastidial and cytosolic ACCases provide malonyl-CoA for de novo FA synthesis in the plastid and FA elongation in the endoplasmic reticulum, respectively. The present study aimed at investigating the expression of plastidial and cytosolic ACCase in Chromera velia and Isochrysis aff. galbana (TISO) and their impact on FA content and elongation level when grown under nitrogen-deplete conditions. In C. velia, plastidial ACCase was significantly upregulated during nitrogen starvation and with culture age, strongly correlating with increased FA content. Conversely, plastidial ACCase of I. aff. galbana was not differentially expressed in nitrogen-deplete cultures, but upregulated during the logarithmic phase of nitrogen-replete cultures. In contrast to plastidial ACCase, the cytosolic ACCase of C. velia was downregulated with culture age and nitrogen-starvation, strongly correlating with an increase in medium-chain FAs. In conclusion, the expression of plastidial and cytosolic ACCase changed with growth phase and nutrient status in a species-specific manner and nitrogen limitation did not always result in FA accumulation. [Copyright &y& Elsevier]

Abstract: To estimate the phylogeny and molecular evolution of a single-copy gene encoding plastid acetyl-CoA carboxylase (Acc1) within the StH genome species, two Acc1 homoeologous sequences were isolated from nearly all the sampled StH genome species and were analyzed with those from 35 diploid taxa representing 19 basic genomes in Triticeae. Sequence diversity patterns and genealogical analysis suggested that (1) the StH genome species from the same areas or neighboring geographic regions are closely related to each other; (2) the Acc1 gene sequences of the StH genome species from North America and Eurasia are evolutionarily distinct; (3) Dasypyrum has contributed to the nuclear genome of Elymus repens and Elymus mutabilis; (4) the StH genome polyploids have higher levels of sequence diversity in the H genome homoeolog than the St genome homoeolog; and (5) the Acc1 sequence may evolve faster in the polyploid species than in the diploids. Our result provides some insight on evolutionary dynamics of duplicate Acc1 gene, the polyploidy speciation and phylogeny of the StH genome species. [Copyright &y& Elsevier]

Highlights: [•] We report the effect of sethoxydim treatment in rape leaves. [•] The lipid metabolism is decreased by malonyl-CoA deficiency. [•] The flavonoid metabolism is stimulated with anthocyanins accumulation. [•] The flux of carbon seems to be oriented towards protective mechanisms. [ABSTRACT FROM AUTHOR]

Highlights: [•] Fluazifop-p-butyl inhibited maize growth. [•] The graminicide affected maize pigment accumulation. [•] Polyamines participated in the response to the herbicide. [•] Phenomenon was related to changes in ODC and LDC activity. [•] The changes were dependent on maize tissue and herbicide dose. [ABSTRACT FROM AUTHOR]

Plastidic acetyl-CoA carboxylase (ACCase) regulates the rate of fatty acid synthesis. This enzyme is composed of biotin carboxyl carrier protein (BCCP), biotin carboxylase (BC), and carboxyltransferase (CT), which consists of α and β subunits. Among these components, CTβ is encoded by the plastidic genome. In Arabidopsis, BC and CTα are each encoded by a single gene, and there are two genes for BCCP, BCCP1 and BCCP2. Promoter analysis revealed that the 5′-UTR containing the AW box is necessary for the expression of these genes in seeds and seedlings. The results indicated that there are other transcription factors besides WRI1 that bind to the AW box and regulate these genes in organs other than seeds. Although the AW boxes at 748 and 532 bp upstream from the transcription start sites (TSSs) of the BC and CTα genes, respectively, were not functional in seeds, the latter was functional in seedlings. In addition, when these AW boxes were moved to approximately 200 bp upstream from the TSS, they became active in seeds but not in seedlings. These results suggest that the distance from the TSS affects the function of the AW box, and the AW box alone is not sufficient for expression in seedlings. A comparison of the protein levels of BC, BCCP1, BCCP2 and CTβ between a wri1 mutant, a WRI1-overexpressing line and control plants showed that protein levels of BCCP2 and BC but not BCCP1 and CTβ are affected by WRI1. The results suggest that ACCase subunits are differentially regulated by WRI1. [ABSTRACT FROM AUTHOR]

Heteromeric acetyl coenzyme A carboxylase (ACCase), a rate-limiting enzyme in fatty acid biosynthesis in dicots, is a multi-enzyme complex consisting of biotin carboxylase, biotin carboxyl carrier protein, and carboxyltransferase (α-CT and β-CT). In the present study, four genes encoding α-CT were cloned from Brassica napus, and two were cloned from each of the two parental species, B. rapa and B. oleracea. Comparative and cluster analyses indicated that these genes were divided into two major groups. The major divergence between group-1 and group-2 occurred in the second intron. Group-2 α-CT genes represented the ancestral form in the genus Brassica. The divergence of group-1 and group-2 genes occurred in their common ancestor 12.96-17.78 million years ago (MYA), soon after the divergence of Arabidopsis thaliana and Brassica (15-20 MYA). This time of divergence is identical to that reported for the paralogous subgenomes of diploid Brassica species (13-17 MYA). Real-time reverse transcription PCR revealed that the expression patterns of the two groups of genes were similar in different organs, except in leaves. To better understand the regulation and evolution of α-CT genes, promoter regions from two sets of orthologous gene copies from B. napus, B. rapa, and B. oleracea were cloned and compared. The function of the promoter of gene Bnα-CT-1-1 in group-1 and gene Bnα-CT-2-1 in group-2 was examined by assaying β-glucuronidase activity in transgenic A. thaliana. Our results will be helpful in elucidating the evolution and regulation of ACCase in oilseed rape. L’acétyle co-enzyme A carboxylase (ACCase) hétéromérique, une enzyme limitante dans la synthèse des acides gras chez les dicotylédones, est un complexe multienzymatique comprenant la biotine carboxylase, la protéine carboxylée transporteuse de biotine et la carboxyltransférase (α-CT et β-CT). Dans ce travail, quatre gènes codant pour l’α-CT ont été clonés chez le Brassica napus de même que deux gènes de chacune des deux espèces parentales, B. rapa et B. oleracea. Des analyses comparées et de groupement ont indiqué que ces gènes forment deux groupes principaux. La divergence majeure entre les groupes 1 et 2 se trouvent au sein du second intron. Les gènes du groupe 2 de l’α-CT constituent la forme ancestrale chez le genre Brassica. La divergence des gènes des groupes 1 et 2 se serait produite au sein de l’ancêtre commun il y a 12,96-17,78 millions d’années (MA), tôt après la divergence entre l’Arabidopsis thaliana et Brassica (15-20 MA). Ce moment de divergence est identique à celui estimé pour la divergence des sous-génomes paralogues au sein des Brassica diploïdes (13-17 MA). Une analyse RT-PCR en temps réel a révélé que l’expression des deux groupes de gènes est semblable au sein de différents tissus à l’exception des feuilles. Afin de mieux connaître la régulation et l’évolution des gènes codant pour l’α-CT, les régions promotrices de deux jeux d’orthologues ont été clonées et comparées chez le B. napus, le B. rapa et le B. oleracea. La fonction du promoteur du gène Bnα-CT-1-1 (appartenant au groupe 1) et celui du gène Bnα-CT-2-1 (appartenant au groupe 2) a été examinée en mesurant l’activité β-glucuronidase chez des lignées transgéniques de l’A. thaliana. Ces résultats seront utiles pour élucider l’évolution et la régulation de l’ACCase chez le colza oléagineux. [ABSTRACT FROM AUTHOR]

Abstract: Palm oil is the second largest traded oil or fat in the world market and palm is the most important crop grown mainly for its oil. Identified varieties of Elaeis guineensis Jacq., with a high oil content and produced through a selective breeding program, are desirable for improving the yield of oil, subsequently enhancing the economic feasibility of using oil palm in various applications, including bio-diesel. We have cloned the gene of biotin carboxylase (accD) from E. guineensis Jacq. This gene encodes a plastid-coded subunit of heteromeric acetyl-CoA carboxylase (ACCase). The cDNA of accD gene (accession number DQ004687) has an open reading frame of 1479bp that encodes a putative protein of 492 amino acid residues (AAY86362) with a predicted molecular mass of 55.47kDa. The heteromeric form of ACCase is important as it catalyzes the first committed step of fatty acid synthesis. There is evidence that collectively suggests that the expression of accD in plastids is crucial to the levels of heteromeric ACCase and in turn, to the amount of seed oil in plant. Here we support the hypothesis that the expression level of accD is correlated with the oil palm production by using a semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) and quantitative real-time polymerase chain reaction (real-time PCR) analysis. Moreover, we observed the similar expression profile in nuclear-encoded subunit, biotin carboxylase (accC). This finding represents the genetic background of the expressed genes that correlate to high yield in plant and that ACCase can be used as a marker in the breeding program. [Copyright &y& Elsevier]

With rare exceptions, dicot plastids have been reported to contain only a multisubunit (prokaryotic) form of acetyl-coA carboxylase (ACCase), the first committed step of lipid biosynthesis. The sensitivity of most monocots to cyclohexanediones (CHDs) such as sethoxydim, has been shown to be associated with the presence in their plastids of a multifunctional (eukaryotic) form of ACCase. Little is known about the effects of sethoxydim on lipid metabolism and ACCase activity in dicots. Here it is shown that foliar lipid biosynthesis is differentially affected by the herbicide treatment in two dicot species, Nicotiana sylvestris (wild tobacco) and Glycine max (soybean). In N. sylvestris, the total lipid content of neoformed leaves harvested 2 weeks after the sethoxydim treatment was unaffected by doses of up to 10−3 M sethoxydim. In soybean, lipid content decreased by 45% when 10−5 M sethoxydim was used, and this was associated with a 30% reduction in fatty acid synthesis activity. ACCase activity of soybean plastidial preparations was 60% reduced in the presence of sethoxydim, whereas that of N. sylvestris was unaffected. Finally, the presence of a biotinylated 220 kDa polypeptide, corresponding in size to multifunctional ACCase, was observed in soybean plastids. Possible relationships between sensitivity of plastidial soybean ACCase towards sethoxydim, plastidial protein content, and altered de novo lipid biosynthesis in herbicide-treated plants are discussed. [ABSTRACT FROM PUBLISHER]

From paddy field observations in 2002 and 2004, fenoxaprop-P-ethyl resistance in Chinese sprangletop (Leptochloa chinensis (L.) Nees) has been studied using information collected from 11 sites in the Saphan-Sung district of Bangkok, Thailand. The resistant Chinese sprangletop was found in nine rice fields, whereas the susceptible Chinese sprangletop was found in only two rice fields. In greenhouse experiments, both fenoxaprop-P-ethyl-resistant and susceptible Chinese sprangletop from the same location were investigated for 50% growth reduction based on phytotoxicity, plant height and fresh and dry weight. The resistant Chinese sprangletop showed apparent resistance at 14–21 days after herbicide application at a rate of 21.1–337.6 g Al ha-1. The resistance index of resistant Chinese sprangletop was 10–25 times higher than that of the susceptible Chinese sprangletop. In addition, Chinese sprangletop did not exhibit multiple resistance to oxadiazon, propanil and quinclorac. According to acetyl-CoA carboxylase (ACCase) assays, the level of ACCase specific activity in the resistant Chinese sprangletop was significantly higher than that in the susceptible Chinese sprangletop. Similarly, the ACCase activity of the resistant Chinese sprangletop was 10 times less sensitive to fenoxaprop-P-ethyl than that of the susceptible Chinese sprangletop, based on the I50 values. The present study of the mechanism responsible for resistance in the biotypes investigated indicated that there was a close association between the concentration-response at the whole-plant level and ACCase sensitivity to fenoxaprop-P-ethyl, and resistance to fenoxaprop-P-ethyl was conferred by a modified ACCase at the target site, as suggested by higher specific activity and less sensitivity to the herbicide. [ABSTRACT FROM AUTHOR]

To investigate the role of carbonic anhydrase (CA; EC 4.2.1.1) and phosphoenolpyruvate carboxylase (PEPC; EC 4.1.1.31) during Medicago sativa seed development, the distribution of both proteins was examined using an immunohistological approach. Both enzymes are co-localized in most ovular and embryonic tissues. In early stages of seed development, both proteins were abundant in embryo and integuments, while at subsequent stages both proteins are accumulated in endosperm, nucellus and integuments. At late stages of seed development when both endosperm and nucellus are degraded, significant accumulation of both proteins was observed in the embryo proper. Chlorophyll was found to accumulate in embryos after the heart stage and reached a maximum at mature stage. It is suggested that CA and PEPC play a role in respiratory carbon dioxide refixation while generating malate to support amino acid and/or fatty acids biosynthesis. [Copyright &y& Elsevier]

Most methods developed for detecting known single nucleotide polymorphisms (SNP) and deletion–insertion polymorphisms (DIP) are dependent on sequence conservation around the SNP/DIP and are therefore not suitable for application to heterogeneous organisms. Here we describe a novel, versatile and simple PCR-RFLP procedure baptised 'derived Polymorphic Amplified Cleaved Sequence' (dPACS) for genotyping individual samples. The notable advantage of the method is that it employs a pair of primers that cover the entire fragment to be amplified except for one or few diagnostic bases around the SNP/DIP being investigated. As such, it provides greater opportunities to introduce mismatches in one or both of the 35–55 bp primers for creating a restriction site that unambiguously differentiates wild from mutant sequences following PCR-RFLP and horizontal MetaPhorTM gel electrophoresis. Selection of effective restriction enzymes and primers is aided by the newly developed dPACS 1.0 software. The highly transferable dPACS procedure is exemplified here with the positive detection (in up to 24 grass and broadleaf species tested) of wild type proline106 of 5-enolpyruvylshikimate-3-phosphate synthase and its serine, threonine and alanine variants that confer resistance to glyphosate, and serine264 and isoleucine2041 which are key target-site determinants for weed sensitivities to some photosystem II and acetyl-CoA carboxylase inhibiting herbicides, respectively. [ABSTRACT FROM AUTHOR]