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Recently, due to the widespread use of the acetolactate synthase (ALS)-inhibiting herbicide penoxsulam in paddy fields in China, Echinochloa crus-galli (L.) P. Beauv. has become a problematic grass weed that is frequently not controlled, posing a threat to weed management and rice yield. There are many reports on target-site mutations of ALS inhibiting herbicides; however, the detailed penoxsulam resistance mechanism in E. crus-galli remains to be determined. Greenhouse and laboratory studies were conducted to characterize target-site resistance mechanisms in JL-R, AH-R, and HLJ-R suspected resistant populations of E. crus-galli survived the field-recommended dose of penoxsulam. The whole-plant dose–response testing of E. crus-galli to penoxsulam confirmed the evolution of moderate-level resistance in two populations, JL-R (9.88-fold) and HLJ-R (8.66-fold), and a high-level resistance in AH-R (59.71-fold) population. ALS gene sequencing identified specific mutations in resistant populations, including Pro-197-His in ALS1 for JL-R, Trp-574-Leu in ALS1 for AH-R, and Pro-197-Leu in ALS2 for HLJ-R. In vitro ALS activity assays demonstrated a significantly higher activity in AH-R compared to the susceptible population (YN-S). Molecular docking studies revealed that Trp-574-Leu mutation primarily reduced the enzyme's ability to bind to the triazole-pyrimidine ring of penoxsulam due to decreased π–π stacking interactions, while Pro-197-His/Leu mutations impaired binding to the benzene ring by altering hydrogen bonds and hydrophobic interactions. Additionally, the Pro-197-His/Leu amino acid residue changes resulted in alterations in the shape of the active channel, impeding the efficient entry of penoxsulam into the binding site in the ALS protein. The three mutant ALS proteins expressed via the Bac-to-Bac baculovirus system exhibited notably lower activity inhibition rates than the non-mutant ALS proteins to penoxsulam, indicating all three ALS mutations reduce sensitivity to penoxsulam. This study elucidated the distinct impacts of the Pro-197-His/Leu and Trp-574-Leu mutations in E. crus-galli to penoxsulam resistance. Notably, the Trp-574-Leu mutation conferred stronger resistance to penoxsulam compared to the Pro-197-His/Leu mutations in E. crus-galli. The Pro-197-His/Leu mutations were first detected in E. crus-galli conferring penoxsulam resistance. These findings provide deeper insights into the molecular mechanisms underlying target-site resistance to penoxsulam in E. crus-galli. [ABSTRACT FROM AUTHOR]

BACKGROUND: Echinochloa crus‐galli is the most troublesome and widespread weed of most rice‐growing regions of the world. Cyhalofop‐butyl, a herbicide within the acetyl‐CoA carboxylase (ACCase) chemical group, has been extensively used to control barnyardgrass in rice. The repeated exposure to cyhalofop‐butyl has led to resistance evolution in E. crus‐galli populations. RESULTS: In this study, we identified a population of E. crus‐galli (R‐HN) in a rice field in Hunan, China, that developed resistance to cyhalofop‐butyl at 4.49‐fold the recommended field dose. No known target mutation was detected in the ACCase gene of the R‐HN population by ACCase sequencing compared to sensitive populations. Both cytochrome P450 (CYP450) and glutathione S‐transferase (GST) inhibitors could not significantly reverse the resistance to cyhalofop‐butyl. The nontarget‐site resistance (NTSR) mechanism was investigated by transcriptome sequencing. Validation of the screened candidate genes by quantitative real‐time (qRT)‐PCR revealed that six glycosyltransferases (GTs) and four ATP‐binding cassette (ABC) transporter genes were consistently upregulated in the R‐HN population. Five GTs and one ABC transporter genes were constitutively upregulated after cyhalofop‐butyl treatment in the R‐HN population. Molecular docking results showed that the significant binding energy of GT79, GT75L6 and GT74E among all candidate genes. CONCLUSION: Thus, the GT genes appear to be directly implicated in NTSR to cyhalofop‐butyl in the R‐HN populations through metabolic enhancement, but their functional characterization needs to be studied. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Recently, due to the widespread use of the acetolactate synthase (ALS)-inhibiting herbicide penoxsulam in paddy fields in China, Echinochloa crus-galli (L.) P. Beauv. has become a problematic grass weed that is frequently not controlled, posing a threat to weed management and rice yield. There are many reports on target-site mutations of ALS inhibiting herbicides; however, the detailed penoxsulam resistance mechanism in E. crus-galli remains to be determined. Greenhouse and laboratory studies were conducted to characterize target-site resistance mechanisms in JL-R, AH-R, and HLJ-R suspected resistant populations of E. crus-galli survived the field-recommended dose of penoxsulam. The whole-plant dose–response testing of E. crus-galli to penoxsulam confirmed the evolution of moderate-level resistance in two populations, JL-R (9.88-fold) and HLJ-R (8.66-fold), and a high-level resistance in AH-R (59.71-fold) population. ALS gene sequencing identified specific mutations in resistant populations, including Pro-197-His in ALS1 for JL-R, Trp-574-Leu in ALS1 for AH-R, and Pro-197-Leu in ALS2 for HLJ-R. In vitro ALS activity assays demonstrated a significantly higher activity in AH-R compared to the susceptible population (YN-S). Molecular docking studies revealed that Trp-574-Leu mutation primarily reduced the enzyme’s ability to bind to the triazole-pyrimidine ring of penoxsulam due to decreased π–π stacking interactions, while Pro-197-His/Leu mutations impaired binding to the benzene ring by altering hydrogen bonds and hydrophobic interactions. Additionally, the Pro-197-His/Leu amino acid residue changes resulted in alterations in the shape of the active channel, impeding the efficient entry of penoxsulam into the binding site in the ALS protein. The three mutant ALS proteins expressed via the Bac-to-Bac baculovirus system exhibited notably lower activity inhibition rates than the non-mutant ALS proteins to penoxsulam, indicating all three ALS mutations reduce sensitivity to penoxsulam. This study elucidated the distinct impacts of the Pro-197-His/Leu and Trp-574-Leu mutations in E. crus-galli to penoxsulam resistance. Notably, the Trp-574-Leu mutation conferred stronger resistance to penoxsulam compared to the Pro-197-His/Leu mutations in E. crus-galli. The Pro-197-His/Leu mutations were first detected in E. crus-galli conferring penoxsulam resistance. These findings provide deeper insights into the molecular mechanisms underlying target-site resistance to penoxsulam in E. crus-galli.

BACKGROUND: Knowledge of herbicidal targets is critical for weed management and food safety. The phytotoxin isovaleric acid (ISA) is effective against weeds with a broad spectrum, carries low environmental risks, and is thus an excellent herbicide lead. However, the biochemical and molecular mechanisms underlying the action of ISA remain unclear. RESULTS: Multi‐omics data showed that acetyl coenzyme A (acetyl‐CoA) was the key affected metabolite, and that citrate synthase (CS) 4 was substantially down‐regulated under ISA treatment in Echinochloa crus‐galli leaves. In particular, the transcript level of EcCS4 was the most significantly regulated among the six genes involved in the top 10 different pathways. The EcCS4 encodes a protein of 472 amino acids and is localized to the cell membrane and mitochondria, similar to the CS4s of other plants. The protein content of EcCS4 was down‐regulated after ISA treatment at 0.5 h. ISA markedly inhibited the CS4 activity in vitro in a concentration‐dependent manner (IC50 = 41.35 μM). In addition, the transgenic rice plants overexpressing EcCS4 (IC50 = 111.8 mM for OECS4‐8 line) were more sensitive, whereas loss‐of‐function rice mutant lines (IC50 = 746.5 mM for oscs4‐19) were more resistant to ISA, compared to wild type (WT) plants (IC50 = 355.6 mM). CONCLUSION: CS4 was first reported as a negative regulator of plant responses to ISA. These results highlight that CS4 is a candidate target gene for the development of novel herbicides and for breeding herbicide‐resistant crops. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The present research is an attempt to manage Barnyard grass (Echinochloa crus-galli), a common rice weed, sustainably by vermicomposting technology. Echinochloa crus-galli (EC) biomass blended with cow dung in combination: 20:80, 40:60, 50:50, 60:40, and 80:20 with two controls 100% CD and 100% EC were vermicomposted for 63 days. Earthworms could not grow well in feedstocks having higher percentage of EC. Total Kjeldahl nitrogen, total available phosphorus and total potassium in final vermicomposts were in the range of 13.6–21.5 g kg−1, 11.8–15.9 g kg−1, and 20.1–27.6 g kg−1, respectively. Respiration rate (42–98 mgCO2 kg−1 VC 48 h−1) confirms vermicompost maturity and falls within the recommended limits (< 120 mgCO2 kg−1 VC 48 h−1). Vermicomposting process reduced the weed mass by 2.20–3.03 folds depicting its effective decomposition. It was inferred from the results that this weed can be converted into nutrient-rich manure employing vermicomposting and this process facilitating the management of E. crus-galli in a cost-effective and environmentally sustainable manner. [ABSTRACT FROM AUTHOR]

Copyright of Revista de Ciências Agrárias is the property of Sociedade de Ciencias Agrarias de Portugal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Many plant species in nature exert significant allelopathic potential as part of the defense mechanism system, many among their secondary metabolites (allelochemicals), including mineral constituents, which are responsible for the suppression of weeds and enhancing crop yield when directly incorporated into paddy fields. Cissus sicyoides is considered a high-potential allelopathic plant because of its invasion in nature and detected allelochemicals from the plant parts in some studies. The objective of this research was to exploit the allelopathic properties of C.sicyoides against paddy weeds and some indicator plants under laboratory bioassays and greenhouse conditions. The results demonstrated that C. sicyoides had significant inhibition on E. crusgalli, tested plants, and other paddy weeds. In the laboratory conditions, the extracts from C.sicyoides leaves inhibited the growth of Echinochloa crus-galli by 54.3%. The powders from C.sicyoides leaves inhibited the emergence of paddy weeds by approximately 100.0%. In the greenhouse conditions, the powders from C.sicyoides leaves by adding after 3 and 13 days inhibited the growth of E. crus-galli and the emergence of paddy weeds by 64.4%. Remarkably, negligible harmful effects on rice growth were observed. The findings of the study may provide useful information for the exploitation of this plant species to effectively control weeds in the rice fields for sustainable agriculture production. [ABSTRACT FROM AUTHOR]

The heights, biomass, and shares in total biomass of one corn and one weed planted at the same time were determined in the pot studies which the effects of different nitrogen doses (0, 120, 240 and 480 kg/ha) given in two periods on the competition of corn with barnyard grass (Echinochloa crus-galli), Johnsongrass (Sorghum halepense), jimsonweed (Datura stramonium) or common purslane (Portulaca oleracea) were evaluated. It has been determined that nitrogen applications contributed to the heights of corn, common purslane and jimsonweed and there has been no difference in the length and biomass of Johnsongrass and barnyard grass. While variable results were obtained in biomass of common purslane, it was observed that increasing nitrogen doses increased the biomass of the jimsonweed and its share from the total biomass. Corn benefited more from nitrogen in competition with weeds other than jimsonweed or was not affected by increased nitrogen doses. It has been concluded that increasing densities of jimsonweed will provide superiority to corn in nitrogen competition and therefore, its management should be given importance. Since nitrogen is a mobile element, it is recommended to prefer to methods such as strip fertilization and fertigation in order to make corn advantageous in competition with weeds. [ABSTRACT FROM AUTHOR]

Penoxsulam is an acetolactate synthase (ALS)-inhibiting herbicide usually applied by post-emergence foliar spraying (PFS) for the control of Echinochloa crus-galli and numerous annual weeds in paddy fields. Herbicides applied by foliar spraying can have negative impacts on the environment, ecosystems, and human health. In this study, the response of E. crus-galli and rice to the PFS and post-emergence water-dispersal (PWD) applications of penoxsulam, and the differences in the detoxification displayed by them between the two treatment methods were compared. The results showed that the PWD application of penoxsulam provides a similar control efficacy against E. crus-galli as PFS at the 1-, 3-, and 5-leaf stages. Meanwhile, the PWD application had a higher safety for the rice. After being treated with 30 g a.i. ha−1 penoxsulam, residues were not detected in the rice treated by the PWD application method, whereas, with the PFS treatment, there was 59.0 µg/kg penoxsulam remaining. With the PFS application, there were many more residues of penoxsulam in the E. crus-galli than with the PWD method; the amount of residues was 32-fold higher 12 h after treatment. The in vitro enzyme activity assays revealed that the activities of ALS, glutathione-S-transferase (GST), and cytochrome P450 monooxygenases (P450) were increased in the PWD treatments, and were 1.5-, 1.3-, and 2.3-fold higher than with PFS 72 h after treatment. The real-time quantitative PCR (qRT-PCR) revealed that the GST1 and P450 genes, CYP81A14, CYP81A12, CYP81A18, and CYP81A21 were upregulated with the PWD application versus PFS in the E. crus-galli. In summary, these results demonstrate that the herbicidal activity was not affected by the upregulation of target and metabolic enzyme activities with the PWD application of penoxsulam. This research could contribute to application strategies reducing the risk of rice injury and environmental impacts by using water-dispersal formulations of penoxsulam. [ABSTRACT FROM AUTHOR]

The use of allelopathic rice varieties has recently been increasing due to their safety and sustainability in weed management. This study aims to investigate the allelopathic effects of rice varieties developed through N-methyl-N-nitrosourea (MNU) mutation on the growth of lettuce and barnyard grass, as well as to establish the relationship between grain quality and the allelopathy of rice plants. Rice straw, husk, and grain samples of rice varieties K1, K2, K3 and K4 were collected and extracted with methanol. The methanol extracts were investigated for antioxidants, total phenolic content (TPC), total flavonoid content (TFC) and the presence of momilactones A (MA) and B (MB). They were subjected to high-performed liquid chromatography (HPLC) coupled with a UV detector and tested for their allelopathic potential. MA and MB were quantified using Liquid Chromatography-Electrospray Ionization-Mass Spectrometry (LC-ESI-MS). The results revealed that mutant varieties exhibited higher antioxidants and TPC in both the grain and straw. Additionally, the mutant varieties increased the presence of MA and MB in the straw and husk. The straw exhibited stronger inhibitory effects compared to the husk. The straw samples from mutant rice varieties exhibited stronger inhibition towards lettuce (Lactuca sativa L.) and barnyard grass (Echinochloa crus-galli L.). Both the straw and husk strongly inhibited seed germination, shoot length and root length in barnyardgrass compared to lettuce. The inhibition was more pronounced in root growth than shoot growth. Rice varieties with higher allelochemical contents in their straw and husk exhibited stronger allelopathic effects. These findings suggest that rice varieties developed through the MNU mutation exhibited higher allelopathic activity compared to their wild-type cultivars. Therefore, the MNU mutation shows promise for breeding allelopathic rice varieties, which can help reduce the reliance on synthetic herbicides for weed control. [ABSTRACT FROM AUTHOR]

Copyright of Anadolu Tarım Bilimleri Dergisi is the property of Ondokuz Mayis Universitesi, Ziraat Fakultesi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Allelopathy is a phenomenon by which plants positively or negatively affect neighboring plants by releasing allelopathic compounds. These allelochemicals are secondary metabolites found in different concentrations in shoots, roots, leaves, flowers, and even pollen grains. Allelochemicals have potential as natural bioherbicides for controlling weeds when applied in the form of extracts or through intercropping, cover cropping, and mulching. The present study was conducted to investigate the allelopathic potential of Ficus nitida leaves against Echinochloa crus-galli L. and Corchorus olitorius L weeds associated with sunflower plant via two application methods (mixing of F. nitida leaf powder with soil and foliar spray of F. nitida leaf powder alcoholic extract). Two pot experiments were carried out for the two summer seasons of 2020 and 2021 in the greenhouse of the National Research Centre (NRC), Dokki, Giza, Egypt. Nine treatments were applied in a completely randomized block design. Three treatments were applied before sowing, namely F. nitida leaf powder was mixed with the soil at rates of 15, 30, and 45 g/pot. The other three treatments of alcoholic leaf powder extract of F. nitida were sprayed twice on both plants and weeds at 10, 20, and 30% (w/v) concentrations. Additionally, three check treatments—healthy (sunflower only), unweeded, and both weeds only—were applied for comparison. The recorded results showed that F. nitida had an allelopathic bioherbicidal effect on both weeds. By increasing the concentration of F. nitida extract, the bioherbicidal potential increased. Moreover, the recorded results showed that foliar spray of alcoholic extract at 30% concentration was the superior application method for controlling weeds. Mixing of F. nitida leaf powder at 45 g/pot ranked second after this superior treatment. A noticeable result is that these two superior treatments improved sunflower growth parameters and yield traits. Quantitative estimation of phenolic compounds and flavonoids demonstrated that the concentration of these allelochemicals is higher in alcoholic extract than in water extract. Moreover, phenolic acid concentrations as detected by high-performance liquid chromatography fractionation are higher in alcoholic extract than in water extract. [ABSTRACT FROM AUTHOR]

In order to determine the best application conditions of fenpyrazone in corn fields, the effects of temperature, light intensity, interval time of rainfall after herbicide application and weed leaf stage on the herbicidal activity of fenpyrazone against barnyard grass Echinochloa crus-galli were studied using whole-plant dose-response experiments in greenhouse. At the temperature of 15-35 ℃, the efficacy of fenpyrazone was increased with the increase in temperature. At the temperature of 20-35 ℃, the efficacy of fenpyrazone tended to be stable, and the GR50 value for barnyard grass was between 2.8-7.6 g/hm² . With the increase in light intensity, the inhibition rate of the fresh weight of barnyard grass by fenpyrazone increased significantly from 41.19% to 90.84%. Fenpyrazone showed strong tolerance to rain erosion and could quickly penetrate the leaf tissues. And there was no significant correlation between its herbicidal activity and the interval time when the rainfall interval after treatment was more than 1 h, with the GR50 value of 1.7-2.4 g/hm² for barnyard grass. The weed leaf stage significantly affected the efficacy of fenpyrazone against barnyard grass. The barnyard grass at 1- to 4-leaf stage was the most sensitive, with the GR50 value of <1.0 g/hm² . In conclusion, to maximize the efficacy of fenpyrazone, it should be applied when the weather is sunny, the temperature is higher than 20 ℃ and the targeted weed of barnyard grass is at the 1- to 4-leaf stage. The herbicide needs to be reapplied in case of rainy weather within 1h after the application. The results provide a scientific basis for further promoting and applying fenpyrazone in corn fields. [ABSTRACT FROM AUTHOR]

Despite increasing knowledge of barnyardgrass (Echinochloa crus-galli) interference with rice, relatively little is known how endophytes improve the ability of rice against barnyardgrass stress. Here, we provided a detailed temporal characterization of rice root-associated microbiomes during co-cultivation with barnyardgrass and a comparison with the microbiomes of weed-free rice plants. Alpha diversity analysis indicated that barnyardgrass had the opposite effects on endophytic bacteria and fungi in rice roots, in terms of the community diversity, richness and coverage at the rice seedling stage. Principal coordinate analysis showed that barnyardgrass had only a minor effect on the community composition of endophytes in rice roots at the rice seedling stage, but showed a significant and maximum interference at the heading stage. Rice recruited many endophytes to resist biotic stress from barnyardgrass, especially for fungi. PICRUSt (phylogenetic investigation of communities by reconstruction of unobserved states) predictive analysis indicated that 23 metabolic pathways of bacteria were overrepresented in rice. In addition, the main trophic mode of fungi was pathotroph according to FUNGuild analysis. A positive correlation between bacteria and fungi in rice roots was found via network analysis. Anaeromyxobacter, Azospira and Pseudolabrys were the vital bacteria, Phaeosphaeria and Funneliformis were the dominant fungi in maintaining the stability of the ecological network. These results provided data and a theoretical basis for the in-depth understanding of what role endophytes play in rice resistance to barnyardgrass stress and will have implications on improving the resistance of rice against biotic stress using root microbiota.

Barnyardgrass (Echinochloa crus-galli) is one of the most problematic weeds infesting rice fields and causes huge crop yield losses. To clarify the resistance pattern and possible mechanisms of resistance in barnyardgrass population JS12 in Jiangsu Province, whole-plant dose-response experiments were conducted to determine the sensitivity to metamifop, and its target- and non-target based mechanisms were clarified by gene sequencing and expression analysis of ACCase gene, as well as synergistic effects on resistance of two metabolic enzyme inhibitors. Finally, the sensitivities of JS12 population to ACCase inhibitors and other herbicides with different modes of action were analyzed to determine the cross- and multi-resistance patterns. Results showed that the JS12 population exhibited 13.71 times high-level resistance to metamifop. No amino acid substitutions conferring metamifop resistance were detected in six copies of ACCase genes in JS12 population, and the gene expression levels of ACCase were significantly lower than that of the susceptible population after herbicide treatment. Both cytochrome P450 inhibitor malathion and glutathione-S-transferase (GST) inhibitor NBD-Cl could significantly increase the susceptibility of JS12 population to metamifop, causing the GR50 (herbicide rate causing growth reduction by 50%) value to decrease from 227.90 g/hm² to 77.51 g/hm2 and 137.93 g/hm², respectively. In addition, the resistant population JS12 had evolved cross-resistance to ACCase inhibitors cyhalofop-butyl, fenoxaprop-p-ethyl, clethodim, and pindoxaden, and multi-resistance to acetolactate synthase (ALS)-inhibiting herbicide penoxsulam and auxin herbicide quinclorac. Nevertheless, it was still susceptible to the new herbicides florpyrauxifen-benzyl and triadimefon. This study suggested that the enhanced herbicide metabolism mediated by cytochrome P450 and GST might be an important reason for herbicide resistance in JS12 population. Florpyrauxifen-benzyl and triadimefon can be used to control the resistant population. [ABSTRACT FROM AUTHOR]

Labdane-related diterpenoids, momilactones A and B were isolated and identified in rice husks in 1973 and later found in rice leaves, straws, roots, root exudate, other several Poaceae species and the moss species Calohypnum plumiforme. The functions of momilactones in rice are well documented. Momilactones in rice plants suppressed the growth of fungal pathogens, indicating the defense function against pathogen attacks. Rice plants also inhibited the growth of adjacent competitive plants through the root secretion of momilactones into their rhizosphere due to the potent growth-inhibitory activity of momilactones, indicating a function in allelopathy. Momilactone-deficient mutants of rice lost their tolerance to pathogens and allelopathic activity, which verifies the involvement of momilactones in both functions. Momilactones also showed pharmacological functions such as anti-leukemia and anti-diabetic activities. Momilactones are synthesized from geranylgeranyl diphosphate through cyclization steps, and the biosynthetic gene cluster is located on chromosome 4 of the rice genome. Pathogen attacks, biotic elicitors such as chitosan and cantharidin, and abiotic elicitors such as UV irradiation and CuCl2 elevated momilactone production through jasmonic acid-dependent and independent signaling pathways. Rice allelopathy was also elevated by jasmonic acid, UV irradiation and nutrient deficiency due to nutrient competition with neighboring plants with the increased production and secretion of momilactones. Rice allelopathic activity and the secretion of momilactones into the rice rhizosphere were also induced by either nearby Echinochloa crus-galli plants or their root exudates. Certain compounds from Echinochloa crus-galli may stimulate the production and secretion of momilactones. This article focuses on the functions, biosynthesis and induction of momilactones and their occurrence in plant species. [ABSTRACT FROM AUTHOR]

ABSTRACT: The resistance of Echinochloa crus-galli (barnyardgrass) to cyhalofop-p-butyl has already been confirmed in rice fields in Santa Catarina, Brazil. However, it is not known if this resistance affects other ACCase inhibitors. This study evaluated the occurrence of cross-resistance in Echinochloa crus-galli biotypes from the main rice-growing regions of Santa Catarina to ACCase inhibitors. The research was conducted in a greenhouse, using a completely randomized design with a factorial scheme that included three ACCase-inhibiting herbicides (cyhalofop-p-butyl, quizalofop-p-ethyl, and profoxydim) belonging to two chemical groups (aryl-oxifenoxi-propionates and cyclohexanediones), eight herbicide doses, and four biotypes evaluated in the F1 generation and two biotypes evaluated in the F2 generation. These biotypes were selected based on the results of a preliminary trial with 21 populations. The herbicides were applied when the plants presented two true leaves. After control evaluations, the lethal dose required to control 50% and 80% of the population (LD50 and LD80) and the resistance factor (RF) were determined by nonlinear regression. The results showed that only one biotype from Tubarão, Santa Catarina met all statistical and agronomic criteria and had cross-resistance to ACCase inhibitors confirmed. In both generations, the RF was greater than 1.0, and the dose required to achieve 80% control exceeded the maximum recommended dose on the label. Resistance levels were higher for herbicides belonging to the aryl-oxifenoxi-propionate chemical group, with RF greater than 7.0. For the cyclohexanedione chemical group, the RF was less than 5.0.

The diversity in structure and herbicidal properties detected in natural phytotoxic compounds could bring about advantages for development bio-herbicides. The present study was carried out search for potential weed inhibitors from the parts of Mimosa pigra L. The ethyl acetate (EtOAc) extract of leaf of M. pigra showed inhibitory activity during the time that Echinochloa crus-galli (barnyardgrass) germinates and grows, which is greater than that of other extracts. From this active extract, potent growth inhibitors were isolated and identified by column chromatography (CC), gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (1H and 13C NMR). The six compounds were purified in this study namely: lupeol (C1, 13.2 mg), stigmastane-3,6-dione (C2, 14.7 mg), quercetin (C3, 20.2 mg), chrysoeriol (C4, 28 mg), methyl gallate (C5, 21.5 mg) and daucosterol (C6, 16.0 mg). The C2 (quercetin) compound completely inhibited the emergency, shoot height and root length of E. crus-galli at 1 mg/mL concentration (IC50 shoot height = 0.56 mg/mL). This was also the first study to report the isolation and allelopathic activity of lupeol, chrysoeriol and daucosterol from M. pigra leaf. Findings of this study highlighted that quercetin from M. pigra may become bio-herbicide to control barnyard grass and other grass weeds for the development of safe agriculture.

We evaluated the allelopathic potential of allelochemicals present in the swamp rice (Oryza sativa L.) varieties. The effects of 10-swamp rice varieties (Inpara 1, Inpara 2, Inpara 3, Inpara 4, Inpara 5, Inpara 6, Inpara 7, Inpara 8 Agritan, Inpara 9 Agritan and Inpara 10 BLB) were studied on two weeds (Echinochloa crus-galli and Monochoria vaginalis). The allelochemicals released as root exudates from these swamp rice varieties were quantified in root and soil samples with high-performance liquid chromatography (HPLC). The results showed that the swamp rice varieties differed in inhibiting the growth of E. crus-galli and M. vaginalis. The variety Inpara 7 caused maximum growth suppression of E. crus-galli (23.9 %) and M. vaginalis (29.3 %) than other varieties. Furthermore, Inpara 3, 4, 6, 7 and 8 varieties also suppressed the growth of test weeds. HPLC analysis indicated that the allelochemicals concentration was significantly higher in roots than in soil, depending on the variety. The p-hydroxybenzoic acid content in the roots was higher than ferulic and p-coumaric acids, but the release of p-coumaric acid contents into the soil was higher than other compounds. The Inpara 3 roots contained higher contents of ferulic and pcoumaric acids than other varieties, while the highest p-hydroxybenzoic content was found in Inpara 2. The ferulic and p-coumaric acids were significantly correlated with weed growth variables. These compounds may play important roles in regulating rice allelopathy. [ABSTRACT FROM AUTHOR]

Barnyardgrass (Echinochloa crus‐galli (L.) Beauv.), an annual species of the family Poaceae, is a major weed problem in rice‐producing countries throughout the globe. Synthetic herbicides can effectively control this grass in rice paddies, but the development of resistant biotypes after the continuous use of the same active ingredients has led to low herbicide efficacy and yield losses. In this review, a summary of resistant‐barnyardgrass cases in global rice production is reported based on data from the International Herbicide‐Resistant Weed Database. The first case of resistant barnyardgrass in rice paddies was to the photosystem‐II inhibitor propanil in the late 1980s. Eighty‐five (85) out of 116 cases in the period from 1986 to 2022 refer to resistant barnyardgrass (E. crus‐galli var. crus‐galli, E. crus‐galli var. formosensis and E. crus‐galli var. zelayensis) in 16 countries. Barnyardgrass has been found resistant to acetolactate synthase (ALS) inhibitors (34 cases), acetyl‐CoA carboxylase (ACCase) inhibitors (23 cases), photosystem‐II inhibitors (11 cases), auxin mimics/cellulose biosynthesis inhibitors (9 cases), very long chain fatty acid inhibitors (6 cases), and microtubule assembly inhibitors (1 case). The majority of all resistance cases reported to the active ingredients penoxsulam, bispyribac‐sodium, and imazamox (ALS inhibitors), cyhalofop‐butyl and fenoxaprop‐ethyl (ACCase inhibitors), propanil (photosystem‐II inhibitors), and quinclorac (auxin mimics/cellulose biosynthesis inhibitors). Although target‐site resistance with specific mutations has been identified, non‐target site resistance mainly through herbicide detoxification is also of great concern increasing the chance of multiple herbicide resistance evolution. Rotation of herbicides should be adopted concerning the modes of action used as well as the application methods to mitigate resistance evolution of this weed in rice paddies. [ABSTRACT FROM AUTHOR]

Despite increasing knowledge of barnyardgrass (Echinochloa crus-galli) interference with rice, relatively little is known how endophytes improve the ability of rice against barnyardgrass stress. Here, we provided a detailed temporal characterization of rice root-associated microbiomes during co-cultivation with barnyardgrass and a comparison with the microbiomes of weed-free rice plants. Alpha diversity analysis indicated that barnyardgrass had the opposite effects on endophytic bacteria and fungi in rice roots, in terms of the community diversity, richness and coverage at the rice seedling stage. Principal coordinate analysis showed that barnyardgrass had only a minor effect on the community composition of endophytes in rice roots at the rice seedling stage, but showed a significant and maximum interference at the heading stage. Rice recruited many endophytes to resist biotic stress from barnyardgrass, especially for fungi. PICRUSt (phylogenetic investigation of communities by reconstruction of unobserved states) predictive analysis indicated that 23 metabolic pathways of bacteria were overrepresented in rice. In addition, the main trophic mode of fungi was pathotroph according to FUNGuild analysis. A positive correlation between bacteria and fungi in rice roots was found via network analysis. Anaeromyxobacter , Azospira and Pseudolabrys were the vital bacteria, Phaeosphaeria and Funneliformis were the dominant fungi in maintaining the stability of the ecological network. These results provided data and a theoretical basis for the in-depth understanding of what role endophytes play in rice resistance to barnyardgrass stress and will have implications on improving the resistance of rice against biotic stress using root microbiota. [ABSTRACT FROM AUTHOR]

Implementation of water‐saving irrigation practices in lowland rice results in increased availability of nitrate (NO3−) in the soil and favours germination of upland weeds. Since plant species show a specific preference for either ammonium (NH4+) or NO3− as nitrogen (N) source, changes in both soil NO3− concentration and weed flora may affect the competition between rice and weeds. Further, the transpirational demand of the atmosphere might affect growth and competitiveness of lowland (wetland) and upland (dryland) weeds differently due to their adaptation to different ecological environments. Therefore, the study aimed to evaluate the effects of N source on growth, N uptake and competition between rice and common upland and lowland weeds under high and low vapour pressure deficit (VPD). Two rice (Oryza sativa) varieties (NU838 and KD18) differing in growth characteristics and two weed species (Echinochloa crus‐galli and Solanum nigrum) differing in their natural habitat were selected and grown hydroponically as monoculture or mixed culture at low or high VPD. N was supplied as 75%/25% or 25%/75% NH4+/NO3−. N uptake rates were measured in the first week, whereas dry matter (DM), N concentration in the plant, total N uptake and the activities of nitrate reductase and glutamine synthetase in the fresh leaves were determined two weeks after the onset of treatments. Independent of N source, both rice varieties and E. crus‐galli took up a larger share of NH4+, whereas S. nigrum took up a larger share of NO3−. N uptake of rice and E. crus‐galli was hardly affected by N source, whereas high NO3− led to significantly higher N uptake rates and total N uptake of S. nigrum. NU838 showed a higher competitiveness against weeds than KD18. In competition, high NO3− decreased the competitiveness of E. crus‐galli against NU838 but increased the competitiveness of S. nigrum against NU838. High VPD did not affect DM but increased N uptake of S. nigrum, leading to increased competitiveness of the weed at high transpirational demand. Competitiveness for N uptake appears to be an important trait as the relative N concentration in mixed plant communities was correlated with the activity of N‐assimilating enzymes and leaf growth, with a stronger response in rice than in weeds. Our results support the hypothesis that increased availability of NO3− in aerobic rice soils may be advantageous for the competitiveness of upland weeds, especially at high VPD, whereas it may be disadvantageous for common lowland weeds. [ABSTRACT FROM AUTHOR]

Fungi colonizing the surface and endosphere of two widespread Poaceae weed species, Avena fatua and Echinochloa crus-galli, were isolated to compare the taxonomic composition between the plant species, location, and year of the seed collection. The seed-degrading potential of Fusarium isolated from the seeds was tested by inoculating seeds of E. crus-galli with spore suspension. Molecular identification of epiphytic and endophytic fungal genera was performed by sequencing the ITS region of rDNA. Endophytes comprised of significantly lower fungal richness compared to epiphytes. A significant taxonomic overlap was observed between the endosphere and seed surface. The most abundant genera were Alternaria, Fusarium, Cladosporium, and Sarocladium. Analysis of similarities and hierarchical clustering showed that microbial communities were more dissimilar between the two plant species than between the years. Fusarium isolates with a high potential to infect and degrade E. crus-galli seeds in laboratory conditions belong to F. sporotrichioides and F. culmorum. [ABSTRACT FROM AUTHOR]

Penoxsulam is an acetolactate synthase (ALS)-inhibiting herbicide usually applied by post-emergence foliar spraying (PFS) for the control of Echinochloa crus-galli and numerous annual weeds in paddy fields. Herbicides applied by foliar spraying can have negative impacts on the environment, ecosystems, and human health. In this study, the response of E. crus-galli and rice to the PFS and post-emergence water-dispersal (PWD) applications of penoxsulam, and the differences in the detoxification displayed by them between the two treatment methods were compared. The results showed that the PWD application of penoxsulam provides a similar control efficacy against E. crus-galli as PFS at the 1-, 3-, and 5-leaf stages. Meanwhile, the PWD application had a higher safety for the rice. After being treated with 30 g a.i. ha−1 penoxsulam, residues were not detected in the rice treated by the PWD application method, whereas, with the PFS treatment, there was 59.0 µg/kg penoxsulam remaining. With the PFS application, there were many more residues of penoxsulam in the E. crus-galli than with the PWD method; the amount of residues was 32-fold higher 12 h after treatment. The in vitro enzyme activity assays revealed that the activities of ALS, glutathione-S-transferase (GST), and cytochrome P450 monooxygenases (P450) were increased in the PWD treatments, and were 1.5-, 1.3-, and 2.3-fold higher than with PFS 72 h after treatment. The real-time quantitative PCR (qRT-PCR) revealed that the GST1 and P450 genes, CYP81A14, CYP81A12, CYP81A18, and CYP81A21 were upregulated with the PWD application versus PFS in the E. crus-galli. In summary, these results demonstrate that the herbicidal activity was not affected by the upregulation of target and metabolic enzyme activities with the PWD application of penoxsulam. This research could contribute to application strategies reducing the risk of rice injury and environmental impacts by using water-dispersal formulations of penoxsulam.

Berberine (Ber) is easy to synthesize and has a variety of biological and pharmacological activities. At present, the existing studies on berberine have focused predominantly on its antibacterial activity; its herbicidal activity is rarely reported. In addition, there are a number of preparations of berberine, which are not enough to solve its shortcomings of low solubility and biological activity and the difficult storage of berberine. Here, berberine was combined with carbon dots to obtain carbon dots-berberine (CDs-Ber) nano formulation. The fluorescence quenching results showed that the CDs-Ber nano drug delivery system was successfully constructed, and the fluorescence quenching mechanism of the two was static quenching. The bioassay results showed that CDs had no adverse effects on the growth of barnyard grass (Echinochloa crus-galli) and redroot pigweed (Amaranthus retroflexus), and had high biocompatibility. Berberine and CDs-Ber predominantly affected the root growth of barnyard grass and redroot pigweed and could enhance the growth inhibition effect on weeds, to some extent. The results of the protective enzyme system showed that both berberine and CDs-Ber could increase the activities of Superoxide dismutase (SOD), Peroxidase (POD), and Catalase (CAT) in barnyard grass, and CDs-Ber had a stronger stress effect on barnyard grass than berberine. The determination of the number of bacterial communities in the soil after the berberine and CDs-Ber treatments showed that there was no significant difference in the effects of the two, indicating that CDs-Ber would not have more negative impacts on the environment. The CDs-Ber nano formulation improved the biological activity of berberine, enhanced the herbicidal effect, and was relatively safe for soil colonies. [ABSTRACT FROM AUTHOR]

The resistance of weeds to herbicides poses a major threat to agricultural production, and non-target-site resistance (NTSR) is often a serious problem as its mechanisms can in some cases confer resistance to herbicides with different modes of action. In this study, we hypothesized that bZIP transcription factors (TFs), which regulate abiotic stress responses in many plants, play a regulatory role in NTSR. Whole-plant assays indicated that the wild grasses Echinochloa crus-galli and E. glabrescens are resistant to the herbicides penoxsulam, cyhalofop-butyl, and quintrione. Transcriptome sequencing then identified 101 and 49 bZIP TFs with differential expression following penoxsulam treatment in E. crus-galli and E. glabrescens , respectively. Twelve of these genes had >60% homology with rice genes. The expression of bZIP88 was considerably up-regulated 6 h after treatment with the three different herbicides, and it was similar between resistant and susceptible populations; however, the relative expression levels before herbicide treatment and 24 h after were the same. We used rice (Oryza sativa ssp. japonica cv Nipponbare) as a model system for functional validation and found that CRISPR-Cas9-knockout of the rice bZIP88 ortholog increased the sensitivity to herbicide, whereas overexpression reduced it. The OsbZIP88 protein was localized to the nucleus. Using ChIP coupled with high-throughput sequencing, OsbZIP88 was found to form a network regulatory center with other TFs such as bZIP20/52/59 to regulate OsKS1 , OsCOE1 , and OsIM1 , which are related to auxin, abscisic acid, brassinosteroids, and gibberellic acid. Based on these results, we have established a database of bZIP TFs corresponding to herbicide stress, and resolved the mechanisms of the positive regulation of herbicide resistance by bZIP88, thereby providing new insights for NTSR. [ABSTRACT FROM AUTHOR]

Environmental conditions can influence herbicide metabolism and interfere with the evolution of weed resistance. This study aimed to evaluate the effect of thermal regimes on the control of barnyardgrass (Echinochloa crus-galli) susceptible and resistant to herbicides of the imidazolinones chemical group. Factor A (biotypes) consisted of one biotype that is susceptible and one that is resistant to imazethapyr; factor B (dose) comprised six imazethapyr doses between 0 and 800 g ha-1 for the resistant biotype and between 0 and 100 g ha-1 for the susceptible biotype; factor C (temperature) consisted of four thermal regimes (16/16 ºC, 25/25 ºC, 16/25 ºC and 25/16 ºC) to which the plants were submitted before and after the herbicide application. Concerning the resistant biotype, the highest control levels were observed in the thermal regimes with temperature fluctuation, especially at 25/16 ºC. At the recommended imazethapyr dose (100 g ha-1), the herbicide resulted in a control level over 90 % at 25/16 ºC and less than 50 % at 16/16 ºC, in the resistant biotype. The shoot dry mass was reduced by more than 80 % at 25/16 ºC and 16/25 ºC and less than 30 % at 16/16 ºC. The temperature conditions to which the plants are subjected in the pre- and post-application period interfere with the level of imazethapyr resistance in barnyardgrass.

BACKGROUND: Barnyardgrass (Echinochloa crus‐galli (L.) P. Beauv) has evolved resistance to the acetolactate synthase (ALS) inhibitor penoxsulam which is used to control weeds in rice fields in China. The present study is conducted to identify the target‐site resistance (TSR) mechanisms conferring resistance in a penoxsulam‐resistant population. RESULTS: The ALS sensitivity in vitro of the resistant population was sixfold lower to penoxsulam than that of the sensitive population. ALS sequencing revealed that no known mutation conferring ALS herbicide resistance was detected. However, a novel mutation Phe‐206‐Leu was identified in the ALS gene. Additionally, ALS gene expression level of the resistant population was lower than that of the sensitive population. Therefore, the penoxsulam resistance was not due to the overexpression of ALS gene. Molecular docking revealed that this mutation may change the interaction of the penoxsulam‐ALS binding and weaken its mutual affinity by approximately 10%. Arabidopsis thaliana transformed with mutant ALS had fourfold greater resistance to penoxsulam and varied cross‐resistance to other ALS herbicides than those transformed with sensitive ALS. Mutant and sensitive ALS proteins expressed by the baculovirus system exhibited different in vitro penoxsulam sensitivity levels. Mutant ALS had eightfold lower sensitivity to penoxsulam than sensitive ALS. CONCLUSION: This report provides clear evidence that the ALS mutation at position 206 (Phe‐206‐Leu) confers penoxsulam resistance in barnyardgrass. Phe‐206 was confirmed to be the ninth amino acid residue related to ALS herbicide resistance in weeds. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Summary: Rice, one of the most consumed cereal crops worldwide, is commonly grown under flooded conditions, which directly influences the nematode community. Meloidogyne graminicola is the predominant species in rice fields, causing significant damage and requiring integrated management practices. This study aimed to investigate the response of different Poaceae crops, soybean, and common weeds of rice to three biotypes of M. graminicola (G1, G2 and G3) recently detected in Brazil. The highest reproduction factor (RF) for the three nematode populations was detected in the weeds Echinochloa colonum and E. crus-galli , followed by rice and Italian ryegrass. Wheat 'TBio Sonic' and millet 'ADR 500' served as poor hosts to the nematodes, whereas black oat, white oat, signalgrass, millet 'ADR 905', maize, wheat 'TBio Toruk', and soybean acted as non-hosts (RF < 1) in both experiments. Of the three M. graminicola biotypes, G1 was the most aggressive, followed by G3 and G2 (lowest RF values). The findings of the current study can support the selection of crop rotation or succession approaches for the management of different biotypes of M. graminicola in irrigated rice fields. [ABSTRACT FROM AUTHOR]

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Silage maize is an important arable crop in Germany. Echinochloa crus-galli is one of the main weed species in this crop. Herbicide treatment, a common practice by conventional maize farmers to control this weed, may cause many negative impacts on non-target species and the wider environment. Post-dispersal seed predation is an important ecosystem service for weed control, but its value is rarely known. To raise social awareness, we aim to estimate the economic benefits of this ecosystem service. The extent of benefits that farmers can receive from the post-dispersal seed predation depends greatly on how farmers control weeds. By using an on-farm pesticide survey, the herbicide application patterns for Echinochloa crus-galli control in maize in the north-eastern Germany is analysed. Based on this, and by using economic surplus and field data from cage experiments, this case study estimated the value of post-dispersal seed predation of Echinochloa crusgalli in 2013 maize fields in Mecklenburg-West Pomerania. This represents one of the first attempts of economic valuation of this ecosystem service.

Labdane-related diterpenoids, momilactones A and B were isolated and identified in rice husks in 1973 and later found in rice leaves, straws, roots, root exudate, other several Poaceae species and the moss species Calohypnum plumiforme. The functions of momilactones in rice are well documented. Momilactones in rice plants suppressed the growth of fungal pathogens, indicating the defense function against pathogen attacks. Rice plants also inhibited the growth of adjacent competitive plants through the root secretion of momilactones into their rhizosphere due to the potent growth-inhibitory activity of momilactones, indicating a function in allelopathy. Momilactone-deficient mutants of rice lost their tolerance to pathogens and allelopathic activity, which verifies the involvement of momilactones in both functions. Momilactones also showed pharmacological functions such as anti-leukemia and anti-diabetic activities. Momilactones are synthesized from geranylgeranyl diphosphate through cyclization steps, and the biosynthetic gene cluster is located on chromosome 4 of the rice genome. Pathogen attacks, biotic elicitors such as chitosan and cantharidin, and abiotic elicitors such as UV irradiation and CuCl2 elevated momilactone production through jasmonic acid-dependent and independent signaling pathways. Rice allelopathy was also elevated by jasmonic acid, UV irradiation and nutrient deficiency due to nutrient competition with neighboring plants with the increased production and secretion of momilactones. Rice allelopathic activity and the secretion of momilactones into the rice rhizosphere were also induced by either nearby Echinochloa crus-galli plants or their root exudates. Certain compounds from Echinochloa crus-galli may stimulate the production and secretion of momilactones. This article focuses on the functions, biosynthesis and induction of momilactones and their occurrence in plant species.

Fungi colonizing the surface and endosphere of two widespread Poaceae weed species, Avena fatua and Echinochloa crus-galli, were isolated to compare the taxonomic composition between the plant species, location, and year of the seed collection. The seed-degrading potential of Fusarium isolated from the seeds was tested by inoculating seeds of E. crus-galli with spore suspension. Molecular identification of epiphytic and endophytic fungal genera was performed by sequencing the ITS region of rDNA. Endophytes comprised of significantly lower fungal richness compared to epiphytes. A significant taxonomic overlap was observed between the endosphere and seed surface. The most abundant genera were Alternaria, Fusarium, Cladosporium, and Sarocladium. Analysis of similarities and hierarchical clustering showed that microbial communities were more dissimilar between the two plant species than between the years. Fusarium isolates with a high potential to infect and degrade E. crus-galli seeds in laboratory conditions belong to F. sporotrichioides and F. culmorum.

BACKGROUND: Tomato is one of the widely cultivated crops worldwide that is affected by several pests, such as fungi (Fusarium oxysoporum, Alternaria solani), bacteria (Pectobacterium carotovorum) and weeds (Cyperus iria L., Amaranthus spinosus). A growing interest has emerged for developing plant‐derived pesticidal compounds to counteract these pests. One attractive alternative is to use barnyard grass (Echinochloa crus‐galli), known to be widely resistant to synthetic herbicides, as a potential biopesticide compound source. RESULTS: Phytochemical screening of the crude extract showed that phenolic compounds were the most abundant component present in barnyard grass. The crude extract was evaluated for antifungal, antibacterial and herbicidal activities. Bioassays showed inhibition against F. oxysporum (10.73 ± 1.30%) and A. solani (20.47 ± 3.51%), the causative agent of Fusarium rot and early blight disease in tomato, respectively. Antibacterial activity against P. carotovorum gave a mean zone of inhibition (paper disc diffusion assay) of 17.00 ± 1.00 mm and an IC50 (dose–response assay) of 2.26 mg mL−1 was observed. Dose–responsive herbicidal activity on the lettuce seed germination bioassay produced an IC50 of 459.30 ppm. Selectivity studies showed inhibition towards C. iria and A. spinosus with no effect on tomato. Lastly, bioassay‐guided fractionation coupled with untargeted metabolomics studies using ultra‐performance liquid chromatography with diode array detection–tandem mass spectrometry mass analyses revealed loliolide and tricin as the putative metabolites present in barnyard grass. CONCLUSION: To date, this is the first reported study on using barnyard grass as a potential alternative biopesticide against tomato pests such as fungi, bacteria and weeds. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Plant parasitic nematodes and weeds are among the many biotic stresses that crops production suffers from during their growing season. Their management relies mainly on chemical pesticides. To decrease the extent of environment degradation and hazards to human health and livestock due to the prolonged use of these chemicals, biological control using soil microorganisms is considered as a new ecofriendly and efficient control method. The main objective of this work was to improve the inhibition of two local bacterial strains, Pseudomonas aeruginosa and Bacillus cereus, against root knot nematode and weed seeds germination. To achieve this goal, protoplast fusion experiments were performed to gather all their properties in bacterial fusants and increase production of such toxic compounds. The results showed that P. aeruginosa was Rifampicin (Rif) resistance, but B. cereus was sensitive. In contrast to this B. cereus was Neomycin (Nm) resistance but P. aeruginosa was sensitive. A total of 40 fusants derived from the protoplast fusion experiments were selected by antibiotic resistance markers. SDS-PAGE analysis of the proteins confirmed that six recombinants acquired and expressed many specific protein bands from their parental strains. Three fusants, No. F7, F20 and F35, were selected and evaluated for their nematicidal potential in comparison with their parent against root knot nematode Meloidogyne incognita J2 and Echinochloa crus-galli and Portulaca oleracea seeds germination during in vitro experiments. Data showed that the fusants exhibited more antagonistic effects than their parents. After 72hrs of exposure, the three fusants caused 80.6, 96.5 and 97.7% mortality as compared to control, while the % mortality after the same duration by P. aeruginosa, B. cereus singly and combined resulted in 52.2, 65.9 and 48.8%, respectively as compared to control. Furthermore, the three fusants completely inhibited the germination of P. oleracea seeds and resulted in small radicals in E. crus-galli seeds as compared to control. These fusants show great potential to be selected as possible potential biopesticide. [ABSTRACT FROM AUTHOR]

A novel protease was purified from Echinochloa crus-galli utilizing precipitation by ammonium sulfate, DEAESephadex ion exchange and Sephacryl S-200 gel filtration. The purified enzyme at final steps of purification has 340 U/ mg of the specific activity acts on casein as substrate and 6.76 purification fold. Studied protease classified as alkaline, active at high temperature, serine protease when subjected to different values of pH, temperatures and inhibitors respectively. Ability of alkaline protease to reduces of silver nitrate to form nanoparticles was observed through color changing, absorbance, scanning electron microscope and energy dispersive-x-ray spectroscopy. Our research is the first work characterizing the synthesis of silver nanoparticles by alkaline protease purified from Echinochloa crus-galli. [ABSTRACT FROM AUTHOR]

Berberine (Ber) is easy to synthesize and has a variety of biological and pharmacological activities. At present, the existing studies on berberine have focused predominantly on its antibacterial activity; its herbicidal activity is rarely reported. In addition, there are a number of preparations of berberine, which are not enough to solve its shortcomings of low solubility and biological activity and the difficult storage of berberine. Here, berberine was combined with carbon dots to obtain carbon dots-berberine (CDs-Ber) nano formulation. The fluorescence quenching results showed that the CDs-Ber nano drug delivery system was successfully constructed, and the fluorescence quenching mechanism of the two was static quenching. The bioassay results showed that CDs had no adverse effects on the growth of barnyard grass (Echinochloa crus-galli) and redroot pigweed (Amaranthus retroflexus), and had high biocompatibility. Berberine and CDs-Ber predominantly affected the root growth of barnyard grass and redroot pigweed and could enhance the growth inhibition effect on weeds, to some extent. The results of the protective enzyme system showed that both berberine and CDs-Ber could increase the activities of Superoxide dismutase (SOD), Peroxidase (POD), and Catalase (CAT) in barnyard grass, and CDs-Ber had a stronger stress effect on barnyard grass than berberine. The determination of the number of bacterial communities in the soil after the berberine and CDs-Ber treatments showed that there was no significant difference in the effects of the two, indicating that CDs-Ber would not have more negative impacts on the environment. The CDs-Ber nano formulation improved the biological activity of berberine, enhanced the herbicidal effect, and was relatively safe for soil colonies.

A population of Echinochloa crus-galli (L.) P. Beauv obtained from direct-seeding rice fields in Jiangxi Province, China, exhibited high resistance levels (13.5-fold) to the acetyl-CoA carboxylase (ACCase)-inhibiting herbicide cyhalofop-butyl. Compared with the susceptible (S) population, this resistant (R) population evolved a cross-resistance to aryloxyphenoxypropionates (APPs) herbicides metamifop (2.9-fold) and fenoxapro-p-ethyl (4.1-fold), cyclohexanediones (CHDs) herbicide clethodim (4.7-fold), phenyl pyrazoline (DEN) herbicide pinoxaden (6.4-fold), and evolved multiple-resistance to acetolactate synthase (ALS)-inhibiting herbicide penoxsulam (3.6-fold), and auxin mimic herbicides quinclorac (>34.7-fold) and florpyrauxifen-benzyl (2.4-fold). ACCase gene sequencing did not reveal the existence of any known mutation point conferring with herbicide resistance. In addition, three metabolic inhibitors—one glutathione—S-transferase (GST) inhibitor (NBD-Cl), and two cytochrome P450 inhibitors (malathion and PBO)—did not reverse the cyhalofop-butyl resistance. Furthermore, enhanced metabolic rates of more than 60% 24 h after treatment with the active compound cyhalofop acid was observed in R plants compared to S plants. Hence, enhanced metabolism activity endows a non-target-site resistance to cyhalofop-butyl in the R population of E. crus-galli. Future research will be required to determine what metabolizing enzyme genes are responsible for cyhalofop-butyl resistance in E. crus-galli.

In the struggle to secure nutrient access and to outperform competitors, some plant species have evolved a biochemical arsenal with which they inhibit the growth or development of neighbouring plants. This process, known as allelopathy, exists in many of today's major crops, including rice. Rice synthesizes momilactones, diterpenoids that are released into the rhizosphere and inhibit the growth of numerous plant species. While the allelopathic potential of rice was recognized decades ago, many questions remain unresolved regarding the biosynthesis, exudation, and biological activity of momilactones. Here, we review current knowledge on momilactones, their role in allelopathy, and their potential to serve as a basis for sustainable weed management. We emphasize the gaps in our current understanding of when and how momilactones are produced and of how they act in plant cells, and outline what we consider the next steps in momilactone and rice allelopathy research. [ABSTRACT FROM AUTHOR]

The genus Echinochloa (Poaceae) includes orphan crops and important agricultural weeds. Here, we assembled the complete chloroplast genome of a diploid Echinochloa species (E. haploclada). The chloroplast genome is 139,844 bp in length, which includes a large single copy region (81,893 bp), a small single copy region (12,533 bp) and two separated inverted repeat regions (45,418 bp). A total of 119 unique genes were annotated, consisting of 83 protein-coding genes, 32 tRNA genes and 4 rRNA genes. Hexaploid E. crus-galli, one of the most serious weeds worldwide, was derived from a hybrid between tetraploid E. oryzicola and an unknown diploid species. Based on chloroplast genomes of eight Echinochloa species (varieties), the phylogenetic analysis showed that E. crus-galli clustered firstly with diploid E. haploclada rather than tetraploid E. oryzicola, supporting previous assumption that E. oryzicola is the paternal donor of E. crus-galli.

BACKGROUND: Clausena lansium (Lour.) Skeels, belonging to the genus Clausena of the family Rutaceae, has a wide range of medical and agricultural activities. Previous studies on agricultural activities have shown that C. lansium extracts and some components have obvious herbicidal activities. In order to study systematically herbicidal activity of this plant, we studied the herbicidal effect of ethyl acetate (EtOAc) extract from the stems and leaves of this plant and further isolated the active compounds. RESULTS: The EtOAc extract inhibited the growth of roots and shoots of Echinochloa crus‐galli (L.) Beauv., and the inhibitory effect of the EtOAc extract on roots were stronger than those on shoots with half maximal inhibitory concentration (IC50) values of 420.45 and 585.05 mg L−1, respectively. Fifteen compounds were subsequently isolated and identified from the stems and leaves of C. lansium, including nine O‐monoterpenoid furanocoumarins and six cinnamamides. Our results showed that most compounds exhibited varying degrees of herbicidal activities to E. crus‐galli. Among them, compounds 3, 8, and 13–15 showed the best inhibitory activities on the growth of E. crus‐galli roots, with inhibition rate values ranging from 70% to 83% at a concentration of 300 mg L−1. Compounds 1 and 2 are two new compounds, and their structures were established as 5‐O‐monoterpenoid furanocoumarin and 8‐O‐monoterpenoid furanocoumarin, and named as claulansicoumarin‐A and ‐B, respectively. CONCLUSION: The EtOAc extract and pure compounds showed noticeable herbicidal activities against E. crus‐galli and indicated a great potential for these natural compounds to be developed as a herbicide. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Tripyrasulfone is currently the only HPPD-inhibiting herbicide that possesses outstanding selectivity even for direct-seeded rice ( Oryza sativa ) when applied POST to control grass weeds; however, the underlying mechanisms remain unclear. In this study, the inhibitory effects of the real active HDT of tripyrasulfone on recombinant 4-hydroxyphenylpyruvate dioxygenase (HPPDs) from rice and barnyard grass ( Echinochloa crus-galli ) were similar, with consistent structural interactions and similar binding energies predicted by molecular docking. However, the HPPD expression level in rice was significantly greater than that in barnyard grass after tripyrasulfone treatment. Tripyrasulfone was rapidly taken up and hydrolyzed into HDT, which was similarly distributed within the whole plants of rice and barnyard grass at 24 h after treatment. Compared with barnyard grass, rice has more uniform epicuticular wax in the cuticle of its leaves, absorbing less tripyrasulfone and metabolizing much more tripyrasulfone. Overall, to a greater extent, the different sensitivities to tripyrasulfone between barnyard grass and rice resulted from metabolic variations.

This study investigated the multiple herbicide resistance (MHR) mechanism of one Echinochloa crus-galli population that was resistant to florpyrauxifen-benzyl (FPB), cyhalofop-butyl (CHB), and penoxsulam (PEX). This population carried an Ala-122-Asn mutation in the acetolactate synthase ( ALS ) gene but no mutation in acetyl-CoA carboxylase ( ACCase ) and transport inhibitor response1 ( TIR1 ) genes. The metabolism rate of PEX was 2-fold higher, and the production of florpyrauxifen-acid and cyhalofop-acid was lower in the resistant population. Malathion and 4-chloro-7-nitrobenzoxadiazole (NBD-Cl) could reverse the resistance, suggesting that cytochrome P450 (CYP450) and glutathione S-transferase (GST) contribute to the enhanced metabolism. According to RNA-seq and qRT-PCR validation, two CYP450 genes ( CYP71C42 and CYP71D55 ), one GST gene ( GSTT2 ), two glycosyltransferase genes ( rhamnosyltransferase 1 and IAAGLU ), and two ABC transporter genes ( ABCG1 and ABCG25 ) were induced by CHB, FPB, and PEX in the resistant population. This study revealed that the target mutant and enhanced metabolism were involved in the MHR mechanism in E. crus-galli .