Search Results (35)

Cyhalofop-butyl, a widely used acetyl-CoA carboxylase (ACCase)-inhibiting herbicide, is increasingly resisted by Echinochloa crus-galli in paddy fields. However, the physiological and molecular mechanisms of this resistance have not been fully elucidated. In this study, a highly resistant population (HL-R, resistance index [RI] = 19.05) from Hulin and a susceptible population (HL-S, RI = 1.00) were used. The results showed that HL-R population exhibited broad-spectrum resistance to five herbicides (RI = 1.98–14.53). No target-site mutations were found in the ACCase gene; instead, its overexpression contributed to target-site resistance (TSR). Metabolic inhibitor assays confirmed non-target-site metabolic resistance (NTSR). Transcriptome and qRT-PCR analyses identified two detoxification-related differentially expressed genes (DEGs; CH01.636, BH02.4557) as key regulators. The activity of the antioxidant enzyme peroxidase (POD) was also associated with resistance. Collectively, the high resistance of HL-R to cyhalofop-butyl is synergistically driven by ACCase overexpression, POD activity and P450/GST-mediated metabolic detoxification. These findings provide theoretical guidance for the management of resistant barnyard grass. Full article

Herbicide resistance in weeds has become a critical challenge in worldwide and Mexican agriculture. Many of these cases involve single, cross and multiple resistance to herbicides that inhibit Acetyl CoA Carboxylase (ACCase), Acetolactate Synthase (ALS), Hydroxyphenyl Pyruvate Dioxygenase (HPPD), and Enolpyruvyl Shikimate Phosphate Synthase (EPSPS) enzymes, as well as auxin mimic herbicides. Documented resistance mechanisms include both target-site resistance (TSR) mutations and various forms of non-target-site resistance (NTSR). In wheat and barley, biotypes with resistance to ACCase, ALS, EPSPS and auxins have been confirmed. Maize–sorghum systems show resistance to ACCase, ALS and EPSPS, and in cotton there are glyphosate-resistant populations of Amaranthus palmeri. Citrus orchards remain the focus of glyphosate resistance. Of concern is the advance of multiple resistance in cereals, exemplified by Avena fatua (ACCase + ALS) and Brassica rapa (EPSPS + ALS + auxin mimics). Unique cases, such as EPSPS resistance in Leptochloa virgata and Bidens pilosa and to HPPD in Setaria adhaerens, are unique to Mexico. These resistance patterns underline the need for robust monitoring and detailed study of molecular and physiological mechanisms, where this has not been done, to inform integrated weed management strategies and curb the spread of weeds. Full article

Asia minor bluegrass (Polypogon fugax), a widespread Poaceae weed, exhibits broad tolerance to abiotic stresses. Validated reference genes (RGs) for reliable RT-qPCR normalization in this ecologically and agriculturally significant species remain unidentified. This study identified eight candidate RGs using transcriptome data from seedling tissues. We assessed the expression stability of these eight RGs across various abiotic stresses and developmental stages using Delta Ct, BestKeeper, geNorm, and NormFinder algorithms. A comprehensive stability ranking was generated using RefFinder, with validation performed using the target genes COR413 and P5CS. Results identified EIF4A and TUB as the optimal RG combination for normalizing gene expression during heat stress, cold stress, and growth stages. EIF4A and ACT were most stable under drought stress, EIF4A and 28S under salt stress, and EIF4A and EF-1 under cadmium (Cd) stress. Furthermore, EIF4A and UBQ demonstrated optimal stability under herbicide stress. Additionally, application of validated RGs revealed higher acetyl-CoA carboxylase gene (ACCase) expression in one herbicide-resistant population, suggesting target-site gene overexpression contributes to resistance. This work presents the first systematic evaluation of RGs in P. fugax. The identified stable RGs provide essential tools for future gene expression studies on growth and abiotic stress responses in this species, facilitating deeper insights into the molecular basis of its weediness and adaptability. Full article

Appropriate nitrogen is required and important in grain yield formation of crops. To elucidate nitrogen regulation of seed yield and quality of rapeseed (Brassica napus L.), field trials were consecutively conducted in two years with three nitrogen levels of 0, 180, and 240 kg ha⁻¹ (the N0, N180, and N240 treatments). The nitrogen application (N-app) induced increasing trend in the nitrogen accumulation in flowering plants (N-acc), number of siliques per plant (silique-num), number of branches per plant (branch-num), number of seeds per silique (seed-num), and seed yield of rapeseed; there were significant correlational relationships between these indexes (excepting seed-num). The N-app, N-acc, and silique-number showed higher effects on the seed yield. The effect of N-app was mainly achieved through influence on the silique-num, branch-num, and seed-num. When the N-app was increased from 180 to 240 kg ha⁻¹, the nitrogen utilization efficiency (NUE) and the partial productivity of nitrogen fertilizer (PPN) of the rapeseed varieties tested showed a decreasing trend; the NR (nitrate reductase) gene expression level and the NR and GS (glutamine synthetase) activity in leaves was significantly increased under the N180 and N240 treatments compared to the N0 treatment, which achieved peak values at 180 kg ha⁻¹ of N-app. The N-app hardly influenced the seed quality, as well as the gene expression and activity of the enzymes ACCase (acetyl-CoA carboxylase), FAD2 (oleic acid desaturase), and FAD3 (omega-3 fatty acid desaturase) in young seed. In conclusion, N-app induced significant increase in seed yield of rapeseed, the NR gene expression level and the NR and GS activity in leaves was improved; the NUE of rapeseed variety showed decreasing trend with increase in N-app level; while N-app hardly influenced the seed quality. Full article

Flusulfinam is a 4-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibiting herbicide applied post-emergence (POST) to control Echinochloa crus-galli (L.) P.Beauv., Leptochloa chinensis (L.) Nees, Digitaria sanguinalis (Linn.) Scop. and other annual weeds in directly seeded and transplanted paddy fields in China, registered in September 2024. Notably, compared with other HPPD inhibitors in rice, flusulfinam exhibits consistently high safety in both japonica and indica rice varieties. Meanwhile, flusulfinam has no target-site cross-resistance with traditional acetolactate synthase (ALS)-inhibiting, acetyl-CoA carboxylase (ACCase)-inhibiting, and auxin herbicides. Moreover, as the only heterocyclic-amide-structured herbicide in the HPPD inhibitors, it poses a low risk of metabolic cross-resistance with the other HPPD inhibitors, making it a promising candidate for managing herbicide-resistant weeds in rice fields. In this study, the baseline sensitivity to flusulfinam of E. crus-galli and L. chinensis in paddy fields in China was established using dose–response assays between June and October 2023. Thirty-nine populations of E. crus-galli and forty-three populations of L. chinensis, collected from rice fields across various major rice-producing regions in China, exhibited susceptibility to flusulfinam. The GR₅₀ values ranged from 0.15 to 19.39 g active ingredient (a.i.) ha⁻¹ for E. crus-galli and from 7.82 to 49.92 g a.i. ha⁻¹ for L. chinensis, respectively, far below the field recommended rate of flusulfinam. Meanwhile, the GR₅₀ values of E. crus-galli and L. chinensis to flusulfinam were both distributed as a unimodal curve, with baseline sensitivity (GR₅₀b) of 6.48 g a.i. ha⁻¹ and 22.38 g a.i. ha⁻¹, respectively. The SI₅₀ value showed 129.27-fold and 6.38-fold variability in flusulfinam sensitivity among the 39 E. crus-galli field populations and 43 L. chinensis filed populations, while the variability declined to 2.99-fold and 2.23-fold when the SI₅₀b value was used. This study substantiated the efficacy of flusulfinam against E. crus-galli and L. chinensis in Chinese paddy fields and furnished a benchmark for monitoring temporal variations in the susceptibility of field populations of E. crus-galli and L. chinensis to flusulfinam. Full article

Beckmannia syzigachne is one of the most competitive weeds in winter wheat fields in China. In this study, 120 suspected resistant populations of Beckmannia syzigachne were collected from the Anhui, Hubei, Jiangsu, and Shandong Provinces from 2017 to 2019. In total, 110 populations exhibited different levels of resistance to clodinafop-propargyl, 114 populations expressed different levels of resistance to mesosulfuron-methyl, and 105 populations were resistant to both herbicides at different levels. The resistant weeds were mainly distributed in Anhui and Jiangsu Provinces. The detection results of acetyl coA carboxylase (ACCase) and acetolactate synthase (ALS) genes in the resistant populations indicated that ACCase gene mutations occurred in 97 out of 110 populations resistant to clodinafop-propargyl and ALS gene mutations occurred in 25 out of 114 populations resistant to mesosulfuron-methyl. There were several mutation types, including Ile-1781-Leu, Trp-2027-Cys, Ile-2041-Asn, Ile-2041-Val, Asp-2078-Gly, and Gly-2096-Ala in the ACCase sequence and Pro-197-Ser, Pro-197-Thr, Pro-197-His, Pro-197-Leu, Asp-376-Glu, and Trp-574-Leu in the ALS sequence. Among these mutation types, Pro-197-His, Asp-376-Glu, and Trp-574-Leu in the ALS sequence were the first identified in Beckmannia syzigachne. Full article

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. Full article

Large crabgrass (Digitaria sanguinalis (L.) Scop.) is one of the major malignant grass weeds in Chinese maize (Zea mays L.) fields, and it has recently developed resistance to the acetolactate synthase (ALS)-inhibiting herbicide nicosulfuron. This study focused on a suspected nicosulfuron-resistant (R) population (LJ-01) of D. sanguinalis, collected from Lujiang County in Anhui Province, China, to explore the resistance level and potential resistance mechanism. Whole-plant dose–response testing confirmed that the LJ-01 population evolved a high level of resistance to nicosulfuron (11.5-fold) compared to the susceptible (S) population, DY-02. The ALS gene sequencing and relative expression assay of the R plants indicated that target gene mutation and overexpression were not responsible for the resistance phenotype. However, pretreatment with malathion, a known cytochrome P450 monooxygenase (P450) inhibitor, alleviated the resistance of the R population to nicosulfuron by approximately 36%. High-performance liquid chromatography (HPLC) analysis revealed that the R plants metabolized nicosulfuron faster than the S plants. Moreover, cross-resistance testing suggested that the R population exhibited low levels of resistance to thifensulfuron-methyl and pyrazosulfuron-ethyl, but it remained susceptible to rimsulfuron. Multiple resistance patterns showed that the R population evolved low resistance to the photosystem inhibitors bromoxynil octanoate and atrazine and sensitivity to the acetyl-CoA carboxylase (ACCase) inhibitor cyhalofop-butyl and the 4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitors tembotrione, mesotrione, and topramezone. This study reports, for the first time, the simultaneous resistance to ALS and different photosystem inhibitors in D. sanguinalis. The nicosulfuron resistance observed in the R population could primarily be attributed to an enhanced metabolism involving P450 enzymes. Full article

Flax (Linum usitatissimum L.), as an important oil-producing crop, is widely distributed throughout the world, and its seeds are rich in polyunsaturated fatty acids (FAs). Previous studies have revealed that Arabidopsis thaliana ACETYL-CoA CARBOXYLASE (AtACCase) is vital for FA biosynthesis. However, the functions of L. usitatissimum AccD (LuAccD) on FA accumulation and seed germination remain unclear. In the present study, we cloned the LuAccD coding sequence from the flax cultivar ‘Longya 10’, identified conserved protein domains, and performed a phylogenetic analysis to elucidate its relationship with homologs from a range of plant species. Ectopic expression of LuAccD in A. thaliana wild-type background enhanced seed FA accumulation without altering seed morphological characteristics, including seed size, 1000-seed weight, and seed coat color. Consistently, the expression of key genes involved in FA biosynthesis was greatly up-regulated in the developing seeds of LuAccD overexpression lines. Additionally, we demonstrated that LuAccD acts as a positive regulator of salt and mannitol tolerance during seed germination in A. thaliana. These results provide important insights into the functions of LuAccD, which facilitates the oil quantity and abiotic stress tolerance of oil-producing crops through genetic manipulation. Full article

Three perennial ryegrass (Lolium perenne) populations (R1, R2, and R3) with suspected resistance (R) to acetolactate synthase (ALS) or acetyl-CoA carboxylase (ACCase) herbicides were collected from wheat (Triticum aestivum) fields in northwestern Greece to study the underlying mechanisms of resistance and their impact on growth rate and competitive ability against wheat. Preemergence and postemergence plant dose–response assays showed that the R1 population was cross-resistant to the ALS inhibitors chlorsulfuron, mesosulfuron + iodosulfuron, and pyroxsulam, but susceptible (S) to imazamox. However, all populations were susceptible to the ACCase inhibitors clodinafop-propargyl, clethodim, diclofop-methyl, and pinoxaden. The analysis of the ALS gene sequence revealed a substitution of Pro197 by His or Leu in the ALS enzyme in L. perenne, which is reported for the first time in this weed and indicates a potential mechanism of target site-mediated resistance. The R1 population grown in the absence or presence of wheat competition displayed similar aboveground biomass and tiller number trends, and therefore similar estimated growth rates. In addition, the aboveground biomass of wheat was similarly reduced by both the R1 and S populations, supporting the evidence of their similar competitive ability against wheat. In general, these findings indicate that there is no clear evidence for the fitness advantage of R1 over the S population. Full article

Walnut (Juglans regia L.) is an important woody oilseed tree species due to its commercial value. However, the regulation mechanism of walnut oil accumulation is still poorly understood, which restricted the breeding and genetic improvement of high-quality oil-bearing walnuts. In order to explore the metabolic mechanism that regulates the synthesis of walnut oil, we used transcriptome sequencing technology and metabolome technology to comprehensively analyze the key genes and metabolites involved in oil synthesis of the walnut embryo at 60, 90, and 120 days after pollination (DAP). The results showed that the oil and protein contents increased gradually during fruit development, comprising 69.61% and 18.32% of the fruit, respectively, during ripening. Conversely, the contents of soluble sugar and starch decreased gradually during fruit development, comprising 2.14% and 0.84%, respectively, during ripening. Transcriptome sequencing generated 40,631 unigenes across 9 cDNA libraries. We identified 51 and 25 candidate unigenes related to the biosynthesis of fatty acid and the biosynthesis of triacylglycerol (TAG), respectively. The expression levels of the genes encoding Acetyl-CoA carboxylase (ACCase), long-chain acyl-CoA synthetases (LACS), 3-oxoacyl-ACP synthase II (KASII), and glycerol-3-phosphate acyl transfer (GPAT) were upregulated at 60 DAP relative to the levels at 90 and 120 DAP, while the stearoyl-ACP-desaturase (SAD) and fatty acid desaturase 2 (FAD2) genes were highly abundantly expressed during all walnut developmental periods. We found that ABSCISIC ACID INSENSEITIVE3 (ABI3), WRINKLEDl (WRI1), LEAFY COTYLEDON1 (LEC1), and FUSCA3 (FUS3) may be key transcription factors involved in lipid synthesis. Additionally, the metabolomics analysis detected 706 metabolites derived from 18 samples, among which, 4 are implicated in the TAG synthesis, 2 in the glycolysis pathway, and 5 in the tricarboxylic acid cycle (TCA cycle) pathway. The combined analysis of the related genes and metabolites in TAG synthesis showed that phospholipid:diacylglycerol acyltransferase (PDAT) genes were highly abundantly expressed across walnut fruit developmental periods, and their downstream metabolite TAG gradually accumulated with the progression of fruit development. The FAD2 gene showed consistently higher expression during fruit development, and its downstream metabolites 18:2-PC and 18:3-PC gradually accumulated. The ACCase, LACS, SAD, FAD2, and PDAT genes may be crucial genes required for walnut oil synthesis. Our data will enrich public databases and provide new insights into functional genes related to lipid metabolism in walnut. Full article

Glycosylation is a common modification reaction in plants. The products obtained upon glycosylation have different biological functions, making glycosylation an important mechanism affecting and regulating the balance of plant growth and metabolism. In this study, we first speculated that Group I in the apple glycosyltransferase family may have a predicted function like UGT83A1, according to gene chip data published online. Subsequently, by real-time PCR (polymerase chain reaction), we analyzed whether the expression of nine glycosyltransferase genes in Group I was induced by our previously reported ACCase (Acetyl-CoA carboxylase) inhibition-based herbicide QPP ((R)-ethyl·2-(4-((6-fluoro-3-methyl-4-oxo-3,4-dihydroquinazolin-2-yl)oxy) phenoxy) propanoate). It was found that expression of the MdUGT83K2 gene in Group I was significantly increased by QPP. In order to determine whether MdUGT83K2 can glycosylate QPP, we confirmed the enzymatic reaction of MdUGT83K2 in vitro and the presence of QPP glycosides in MdUGT83K2 transgenic apple seedlings by HPLC (High Performance Liquid Chromatography), and found that MdUGT83K2 can transfer glucose to QPP in vivo, which is glycosylated. In this work, we identified a novel apple glycosyltransferase, MdUGT83K2, which functions to glycosylate the ACCase-inhibiting herbicide QPP and may be involved in plant detoxification. Key Contribution: A novel apple glycosyltransferase, MdUGT83K2, was identified, which may be involved in plant detoxification by glycosylation modification of the ACCase-inhibiting herbicide. Full article

Italian ryegrass (Lolium multiflorum L.), a cross-pollinated grass, is gradually becoming a predominant weed in wheat fields in China and is evolving resistance to many groups of herbicides. The aim of this study is to determine the resistance levels of a single L. multiflorum population from a wheat field in Henan Province China, to three modes of action (MoAs) of herbicides and to further characterize the potential resistance mechanisms. This L. multiflorum population evolved multiple herbicide resistances to pyroxsulam [acetolactate synthase (ALS)], pinoxaden [acetyl-CoA carboxylase (ACCase)] and isoproturon [photosystem II (PSII)]. Target-site resistance (TSR) mutations (Pro-197-Gln, Pro-197-Thr, and Trp-574-Leu) and non-target-site resistance (NTSR) mediated by cytochrome P450 monooxygenase (CYP450) genes were associated with pyroxsulam resistance. Pinoxaden resistance was conferred by two TSR mutations, which referred to a rare Ile-2041-Val mutation and a common Ile-1781-Leu mutation but with two different nucleotide substitutions (CTA/TTA). CYP450- and glutathione-S-transferase (GST)-mediated resistances were the main resistance mechanisms for this multiple herbicide-resistant (MHR) population to the PSII inhibitor isoproturon. This is the first case of a single L. multiflorum population evolving multiple resistance to three herbicide MoAs (ALS, ACCase and PSII) in China. Diverse resistance mechanisms including TSR and NTSR mean L. multiflorum exhibits a high degree of resistance plasticity. Full article

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. Full article

Chinese sprangletop (Leptochloa chinensis (L.) Nees) is recognized as the most disturbing weed in rice fields in Africa, Australia, and Asia due to causing a significant reduction in yields. The habit of most lowland rice farmers in Indonesia is using high doses of herbicides more than once without any rotation, leading to increased weed resistance potential. Therefore, this study aimed to confirm the resistance level of L. chinensis to acetyl-CoA carboxylase (ACCase)-inhibiting herbicides using the whole-plant pot test method. We identified other herbicides that can control the resistant biotype and performed DNA sequencing on a sample to determine mutations present in the biotype′s ACCase gene through polymerase chain reaction. The herbicide dose–response experiment showed that the L. chinensis from Bantimurung Subdistrict, Maros Regency, South Sulawesi, exhibited resistance to ACCase inhibitors (metamifop and cyhalofop-butyl), which is the first case of resistance to ACCase herbicides reported in Indonesia. An acetolactate synthase inhibitor (bispyribac-sodium) and a 1-deoxy-d-xylulose-5-phosphate synthase (DOXP) inhibitor (clomazone) were effective at controlling the resistant biotypes of L. chinensis, so could considered for use in rotation or as an ingredient in mixed herbicides. Single-nucleotide substitution of guanine for thiamine at position 6081 (TGG; susceptible, TGT; Maros) that causes a Trp₂₀₂₇Cys mutation in the target gene contributes to the resistance of the Maros biotype to ACCase inhibitors. Full article