Germination characteristics associated with nicosulfuron resistance in Amaranthus retroflexus L.

Nicosulfuron-resistant biotype (R) and -sensitive biotype (S) Amaranthus retroflexus L. seeds were subjected to different temperature, light, salt, osmotic potential, pH value and burial depth treatments. The difference in germination response of two populations to the above abiotic environmental factors was used to study the fitness cost of nicosulfuron-resistance evolution in A. retroflexus. The aim is to find a powerful tool for weed control in the presence of evolutionary resistance selection. The results of this experiment showed that the germination rate and germination index in S population were generally higher than that in R population. When the salt stress was 80 mM, the water potential was -0.1 Mpa ~ -0.4 Mpa, and under strong acid and alkali conditions, the germination index in S population was prominently higher than that in R population (p<0.05). The delayed seed germination in R population indicated that its nicosulfuron resistance may be linked to seed biochemical compositions that altered seed germination dynamics. The resistant and sensitive biotype of A. retroflexus had differently favourable adaptability in diverse environments. Salt, osmotic potential and pH value are not the major constraints for A. retroflexus germination, however, A. retroflexus are strongly responsive to temperature, light and burial depth. Considering that seeds of A. retroflexus are unable to reach the soil surface beyond the depth of 6 cm, deep inversion tillage before sowing may be an effective and economical weed management tool for the control of nicosulfuron resistant A. retroflexus.

Target gene overexpression and enhanced metabolism confer resistance to nicosulfuron in Eriochloa villosa (Thunb.).

Eriochloa villosa (Thunb.) Kunth is a troublesome weed widely distributed in maize (Zea mays L.) fields in Northeast China. Many populations of E. villosa have evolved resistance to nicosulfuron herbicides, which inhibit acetolactate synthase (ALS). The objectives of this research were to confirm that E. villosa is resistant to nicosulfuron and to investigate the basis of nicosulfuron resistance. Whole-plant dose-response studies revealed that the R population had not developed a high level of cross-resistance and exhibited greater resistant (25.62-fold) to nicosulfuron than that of the S population and had not yet developed a high level of cross-resistance. An in vitro ALS activity assay demonstrated that the I50 of nicosulfuron was 6.87-fold greater in the R population than the S population. However, based on ALS gene sequencing, the target ALS gene in the R population did not contain mutations. Quantitative real-time polymerase chain reaction (qRT-PCR) revealed that ALS gene expression between the R and S populations was significantly different after nicosulfuron application, but no differences were observed in the gene copy number. After the cytochrome P450 inhibitor malathion or the GST inhibitor NBD-Cl was applied, the resistant E. villosa population exhibited increased sensitivity to nicosulfuron. Based on the activities of GSTs and P450s, the activities of the R population were greater than those of the S population after nicosulfuron application. This is the first report that the resistance of E. villosa to ALS inhibitors results from increased target gene expression and increased metabolism. These findings provide a theoretical foundation for the effective control of herbicide-resistant E. villosa.

α-mangostin derivatives ameliorated mouse DSS-induced chronic colitis via regulating Th17/Treg balance.

Th17 cell, an important subpopulation of helper T cell, plays an important role in the development of inflammatory bowel disease (IBD) and is thought to be a potential target for the treatment of IBD. In our previous study, we demonstrated that α-mangostin could relieve lupus nephritis via inhibiting Th17 cell function. In our preliminary study, we obtained four derivatives by adding chemical modification of α-mangostin which could also inhibit Th17 cell differentiation in vitro. In this study, we constructed a chronic IBD mouse model and demonstrated the therapeutic effects of α-mangostin and its derivatives as therapeutic agents for IBD. In compounds treating groups, intestinal inflammation showed significant improvement in symptoms which included weight loss, high disease activity index, colon length shorten and the change of intestinal flora. We also found that compounds could effectively either suppress the number of Th17 cell or increase the number of Treg cell detected by flow cytometry, thus reducing the Th17/Treg ratio and suppressing the level of intestinal inflammation. Notably, IL17-F levels, rather than IL17-A, were reduced in the colon of mice of compounds treating groups. Thus, α-mangostin and its derivatives ameliorate DSS-induced chronic colitis in mice by regulating Th17/Treg balance to alleviate intestinal inflammation and can modulate the intestinal microbial community. These results suggest that α-mangostin and its derivatives may be the new therapeutic option for chronic colitis.

Fenoxaprop-P-ethyl, mesosulfuron-ethyl, and isoproturon resistance status in Beckmannia syzigachne from wheat fields across Anhui Province, China.

Severe infestations of American sloughgrass (Beckmannia syzigachne (Steud.) Fernald) in wheat fields throughout Anhui Province, China, pose a significant threat to local agricultural production. This study aims to evaluate the susceptibility of 37 B. syzigachne populations collected from diverse wheat fields in Anhui Province to three commonly used herbicides: fenoxaprop-P-ethyl, mesosulfuron-ethyl, and isoproturon. Single-dose testing revealed that out of the 37 populations, 31, 26, and 11 populations had either evolved or were evolving resistance to fenoxaprop-P-ethyl, mesosulfuron-ethyl, and isoproturon, respectively. Among them, 25 populations displayed concurrent resistance to both fenoxaprop-P-ethyl and mesosulfuron-ethyl, while eight exhibited resistance to all three tested herbicides. Whole-plant bioassays confirmed that approximately 84% of the fenoxaprop-P-ethyl-resistant populations manifested high-level resistance (resistance index (RI) ≥10); 62% of the mesosulfuron-ethyl-resistant populations and 82% of the isoproturon-resistant populations exhibited low- to moderate-level resistance (2 ≤ RI <10). Three distinct target-site mutations were identified in 27% of fenoxaprop-P-ethyl-resistant populations, with no known resistance mutations detected in the remaining herbicide-resistant populations. The inhibition of cytochrome P450s (P450s) and/or glutathione S-transferases (GSTs) substantially increased susceptibility in the majority of resistant populations lacking mutations at the herbicide target site. In conclusion, resistance to fenoxaprop-P-ethyl and mesosulfuron-ethyl was widespread in B. syzigachne within Anhui Province's wheat fields, while resistance to isoproturon was rapidly evolving due to its escalating usage. Target-site mutations were present in approximately one-third of fenoxaprop-P-ethyl-resistant populations, and alternative mechanisms involving P450s and/or GSTs could explain the resistance observed in most of the remaining populations.

ALS gene overexpression and enhanced metabolism conferring Digitaria sanguinalis resistance to nicosulfuron in China.

Crabgrass (Digitaria sanguinalis) is a common malignant weed in corn fields in China. Recently, the acetolactate synthase (ALS) inhibitor, nicosulfuron, has shown decreasing efficacy against crabgrass. In order to elucidate the molecular basis of resistance to nicosulfuron in crabgrass, we conducted bioassays, combined with gene sequence analysis, relative expression and relative copy number analysis, to characterize resistance in crabgrass populations collected from Beijing, Heilongjiang, Jilin and Anhui provinces. Whole-plant dose-response results indicated that only population collected in Heilongjiang province (HLJ) had developed low level of resistance to nicosulfuron compared with the sensitive population (SD22). No known resistant mutation of ALS gene was found in HLJ population. The real-time fluorescence quantitative PCR results showed that the ALS gene copy number did not differ significantly between the HLJ and SD22 populations. However, the ALS gene expression in the HLJ was 2.07-fold higher than that of the SD22 population at 24 h after treatment with nicosulfuron. Pretreatment with the cytochrome P450 (CYP450) inhibitor malathion, piperonyl butoxide (PBO), and the glutathione S-transferase (GST) inhibitor 4-Chloro-7-nitro-1,2,3-benzoxadiazole (NBD-Cl) all partially reversed HLJ resistance. Among them, the synergistic effect of PBO and nicosulfuron is the most significant. This is the first report of resistance to nicosulfuron in crabgrass through ALS gene overexpression and possible metabolic resistance.

Target-site and non-target-site based resistance to clodinafop-propargyl in wild oats (Avena fatua L.).

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

Weed genomics: yielding insights into the genetics of weedy traits for crop improvement.

Weeds cause tremendous economic and ecological damage worldwide. The number of genomes established for weed species has sharply increased during the recent decade, with some 26 weed species having been sequenced and de novo genomes assembled. These genomes range from 270 Mb (Barbarea vulgaris) to almost 4.4 Gb (Aegilops tauschii). Importantly, chromosome-level assemblies are now available for 17 of these 26 species, and genomic investigations on weed populations have been conducted in at least 12 species. The resulting genomic data have greatly facilitated studies of weed management and biology, especially origin and evolution. Available weed genomes have indeed revealed valuable weed-derived genetic materials for crop improvement. In this review, we summarize the recent progress made in weed genomics and provide a perspective for further exploitation in this emerging field.

Molecular Characterization of Resistance to Nicosulfuron in Setaria viridis.

The green foxtail, Setaria viridis (L.) P. Beauv. (Poales: Poaceae), is a troublesome and widespread grass weed in China. The acetolactate synthase (ALS)-inhibiting herbicide nicosulfuron has been intensively used to manage S. viridis, and this has substantially increased the selection pressure. Here we confirmed a 35.8-fold resistance to nicosulfuron in an S. viridis population (R376 population) from China and characterized the resistance mechanism. Molecular analyses revealed an Asp-376-Glu mutation of the ALS gene in the R376 population. The participation of metabolic resistance in the R376 population was proved by cytochrome P450 monooxygenases (P450) inhibitor pre-treatment and metabolism experiments. To further elucidate the mechanism of metabolic resistance, eighteen genes that could be related to the metabolism of nicosulfuron were obtained bythe RNA sequencing. The results of quantitative real-time PCR validation indicated that three ATP-binding cassette (ABC) transporters (ABE2, ABC15, and ABC15-2), four P450 (C76C2, CYOS, C78A5, and C81Q32), and two UDP-glucosyltransferase (UGT) (UGT13248 and UGT73C3), and one glutathione S-transferases (GST) (GST3) were the major candidates that contributed to metabolic nicosulfuron resistance in S. viridis. However, the specific role of these ten genes in metabolic resistance requires more research. Collectively, ALS gene mutations and enhanced metabolism may be responsible for the resistance of R376 to nicosulfuron.

Target gene mutation and enhanced metabolism confer fomesafen resistance in an Amaranthus retroflexus L. population from China.

Amaranthus retroflexus L., a troublesome annual dicotyledonous weed species, is highly competitive with soybean (Glycine max L.). A single-dose herbicide-resistance screening assay identified an A. retroflexus population with suspected resistance to fomesafen. Whole-plant dose-response assays demonstrated that the resistant population (2492) was resistant to protoporphyrinogen oxidase (PPO)-inhibiting herbicides (50.6-fold fomesafen resistance and > 8.1-fold lactofen resistance) compared to a susceptible (S) population. PPX2 gene sequence analysis showed an Arg128Gly amino acid substitution in the 2492 population. Moreover, pretreatment of malathion and the fomesafen metabolic assays through HPLC-MS demonstrated enhanced fomesafen metabolism in the 2492 population. Additionally, the 2492 population was 10.4-fold more resistant to the ALS-inhibiting herbicide imazethapyr and 16.8-fold more resistant to thifensulfuron-methyl than the S population. ALS gene sequence analysis showed an Ala205Val amino acid substitution in the 2492 population. This population of A. retroflexus has coexisting target-site resistance and non-target-site mechanisms for resistance to fomesafen. Multiple herbicide resistance may mean it is necessary to adjust weed management strategies to better control the resistant population.

First Report of the Molecular Mechanism of Resistance to Tribenuron-Methyl in Silene conoidea L.

Silene conoidea L. is an annual troublesome broadleaf weed in winter wheat fields in China. In recent years, field applications of tribenuron-methyl have been ineffective in controlling S. conoidea in Hebei Province, China. The aim of this study was to determine the molecular basis of tribenuron-methyl resistance in S. conoidea. Whole-plant response assays revealed that the resistant population (R) exhibited a higher level of resistance (382.3-fold) to tribenuron-methyl. The R population also showed high cross-resistance to other acetolactate synthase (ALS) inhibitors, including imazethapyr, bispyribac-sodium and florasulam. However, the R population could be controlled by the field-recommended rates of bentazone, MCPA, fluroxypyr, carfentrazone-ethyl and bromoxynil. In vitro ALS activity assays indicated that the tribenuron-methyl I50 value for the R population was 18.5 times higher than those for the susceptible population (S). ALS gene sequencing revealed an amino acid mutation, Trp-574-Leu, in the R population. Pretreatment with the P450 inhibitor malathion indicated that the R population might have cytochrome P450-mediated metabolic resistance. These results suggest that the Trp-574-Leu mutation and P450-mediated enhanced metabolism coexist in S. conoidea to generate tribenuron-methyl resistance. This is the first time that target-site and non-target-site resistance to tribenuron-methyl has been reported in S. conoidea.

Growth and Competitiveness of ALS-Inhibiting Herbicide-Resistant Amaranthus retroflexus L.

The evolved acetolactate synthase (ALS) inhibiting herbicide-resistant redroot amaranth has been confirmed in China and caused a great loss in soybean production. This study was conducted to evaluate the growth and competitiveness of ALS-resistant (R) and ALS-susceptible (S) redroot amaranth biotypes. Seeds of both R and S biotypes were subjected to different temperature regimes. Data revealed that the germination percentage and seedling vigor of both biotypes did not differ largely from each other at 10/20 to 30/40 °C. Under noncompetitive conditions, there were no significant leaf number, plant height, or dry weight differences between the R and S biotypes. Moreover, replacement series experiment results indicated that the R and S biotypes have a similar competitive ability. This study shows that there are no significant differences in growth or competitiveness between the R and S redroot amaranth biotypes regarding the physiological characteristics evaluated. Therefore, the proportion and distribution of the R biotype will not be affected in the absence of the ALS-inhibiting herbicide. Some other effective management practices should be adopted to cope with this troublesome weed.

Multiple resistance to ALS-inhibiting and PPO-inhibiting herbicides in Chenopodium album L. from China.

Common lambsquarters (Chenopodium album L.) is a broadleaf weed that can severely damage soybean fields. Two C. album populations (1744 and 1731) suspected resistant to imazethapyr were investigated for resistance levels to imazethapyr, thifensulfuron-methyl, and fomesafen and their resistance mechanisms were investigated. Whole-plant dose-response assays revealed that, compared to the susceptible (S) population, the 1744 population was 16.5-fold resistant to imazethapyr, slightly resistant to thifensulfuron-methyl (resistance index [R/S], <3). The 1731 population was 18.8-fold resistant to imazethapyr, 2.9-fold resistant to thifensulfuron-methyl, and 5.1-fold resistant to fomesafen. In vitro acetolactate synthase (ALS) assays showed 17.1-fold and 19.3-fold resistance levels of 1744 and 1731 populations to imazethapyr respectively. ALS gene sequence analysis identified Ala122Thr amino acid substitution in the 1744 population and Ser653Thr amino acid substitution in the 1731 population. No mutations of the protoporphyrinogen oxidase (PPO) gene were detected. However, pre-treatment with malathion reversed fomesafen resistance, suggesting nontarget-site resistance mechanisms likely play a role in the 1731 population.

Investigation of resistance mechanisms to bentazone in multiple resistant Amaranthus retroflexus populations.

Redroot amaranth (Amaranthus retroflexus L.) is a noxious weed that affects soybean production in China. Experiments were conducted to determine the molecular basis of resistance to bentazone. Whole-plant dose-response experiments showed that two populations (R1 and R2) exhibited resistance to bentazone with resistance indices of 9.01 and 6.85, respectively. Sequencing of the psbA gene revealed no amino acid substitution in the two populations. qRT-PCR analysis verified that psbA gene expression in R1 and R2 populations was increased significantly after treatment with bentazone, which was 3-fold and 5-fold higher than that in S1 and S2 populations, respectively. The P450 inhibitor malathion significantly reduced the level of resistance in the R1 and R2 populations when used prior to bentazone treatment. The R1 population exhibited multiple resistance to thifensulfuron-methyl and lactofen, caused by target site mutations (Asp-376-Glu in ALS, Arg-128-Gly in PPO2). In conclusion, increased gene expression of the psbA gene and enhanced herbicide metabolism seem to be the basis of resistance to bentazone in these A. retroflexus populations.

Pro-197-Ser Mutation and Cytochrome P450-Mediated Metabolism Conferring Resistance to Flucarbazone-Sodium in Bromus japonicus.

In crop fields, resistance to acetolactate synthase (ALS)-inhibiting herbicides found in many troublesome weed species, including Bromus japonicus Thunb, is a worldwide problem. In particular, the development of herbicide resistance in B. japonicus is a severe threat to wheat production in China. The purpose of this research was to investigate the physiological and molecular basis of B. japonicus resistance to flucarbazone-sodium. Dose-response analysis demonstrated that, compared with the susceptible B. japonicus (S) population, the resistant (R) population exhibited a 120-fold increase in flucarbazone-sodium resistance. Nucleotide sequence alignment of the ALS gene indicated that the Pro-197-Ser mutation in ALS was associated with resistance to flucarbazone-sodium in the R population. The results of a malathion pretreatment study showed that B. japonicus might also have remarkable cytochrome P450 monooxygenase (P450)-mediated metabolic resistance. This is the first report of a Pro-197-Ser mutation and P450-mediated metabolism conferring resistance to flucarbazone-sodium in B. japonicus.

Mechanism of Resistance to Pyroxsulam in Multiple-Resistant Alopecurus myosuroides from China.

Black grass (Alopecurus myosuroides Huds.) is a highly competitive weed in winter wheat fields of China. Due to repeated use of acetolactate synthase (ALS) inhibitors, many A. myosuroides populations have evolved resistance to pyroxsulam in some wheat fields. Research was conducted to determine the molecular basis of herbicide resistance in the AH93 A. myosuroides population. Whole-plant dose-response assay confirmed that the AH93 population was resistant to pyroxsulam with a resistance index of 4.2. Cross- and multiple-resistance assays indicated that the AH93 population was cross-resistant to mesosulfuron-methyl and multiple-resistant to pinoxaden. Sequencing of the ALS and ACCase gene revealed that there was no target-site mutation in ALS, but Trp-2027-Cys and Cys-2088-Arg amino acid mutations in ACCase in the AH93 population. A malathion pretreatment study indicated that the AH93 population might have cytochrome P450-mediated herbicide metabolic resistance. This is the first report of pyroxsulam resistance in a multiple-resistant A. myosuroides population in China, and the Cys-2088-Arg mutation is the first reported case of an ACCase mutant conferring herbicide resistance in A. myosuroides.

Multiple resistance to ACCase- and ALS-inhibiting herbicides in black-grass (Alopecurus myosuroides Huds.) in China.

Two black-grass (Alopecurus myosuroides Huds.) populations (R2105 and R1027) that were suspected to be resistant to clodinafop-propargyl, an acetyl-CoAcarboxylase (ACCase) inhibitor, were found in winter wheat fields in China. Research was carried out to investigate whether resistance to clodinafop-propargyl was present and the molecular mechanism of herbicide resistance in these two populations. Dose-response assays confirmed high level resistance to clodinafop-propargyl in both R2105 and R1027 populations, with resistance indexes 25.1 and 22.1. ACCase gene sequence comparison revealed three amino acid mutations (Trp-1999-Leu, Ile-2041-Asn, or Asp-2078-Gly) in R2105 population and Ile-2041-Asn mutation in R1027 population. Sensitivity to other herbicides assays indicated that R2105 and R1027 populations were cross resistant to fenoxaprop-P-ethyl and multiple resistant to pyroxsulam and mesosulfuron-methyl. The ALS gene sequence analysis revealed that all resistant individuals in R2105 and R1027 populations had the Trp-574-Leu mutation. Applying malathion, significantly decreased the rate of metabolism of clodinafop-propargyl in both R2105 and R1027 populations. This is the first report of multiple resistance to ACCase- and ALS-inhibiting herbicides conferred by target-site mutations and enhanced metabolism in black-grass in China.

Delivery of CD47 blocker SIRPα-Fc by CAR-T cells enhances antitumor efficacy.

BACKGROUND: Chimeric antigen receptor (CAR) T cell therapy has been successfully applied in treating lymphoma malignancies, but not in solid tumors. CD47 is highly expressed on tumor cells and its overexpression is believed to inhibit phagocytosis by macrophages and dendritic cells. Given the antitumor activity against preclinical model of CD47-blocking to induce the innate and adaptive immune system in the tumor microenvironment, here we developed a CAR-T cell secreting CD47 blocker signal regulatory protein α (SIRPα)-Fc fusion protein (Sirf CAR-T) to boost CAR-T cell therapeutic effect in solid tumor therapy. METHODS: Murine T cells were transduced to express a conventional anti-Trop2 CAR and Sirf CAR. The expression of SIRPα-Fc fusion protein in the supernatant of CAR-T cells and its effect on macrophage phagocytosis were tested in vitro. In vivo antitumor efficacy of CAR-T cells was evaluated in immunocompetent mice and analysis of the tumor microenvironment in the tumor-bearing mice was performed. RESULTS: We found that Sirf CAR-T cells dramatically decreased tumor burden and significantly prolonged survival in several syngeneic immunocompetent tumor models. Furthermore, we found that Sirf CAR-T cells induced more central memory T cells (TCM) and improved the persistence of CAR-T cells in tumor tissue, as well as decreased PD-1 expression on the CAR-T cell surface. In addition, we demonstrated that Sirf CAR-T cells could modulate the tumor microenvironment by decreasing myeloid-derived stem cells as well as increasing CD11c+ dendritic cells and M1-type macrophages in tumor tissue. CONCLUSIONS: In summary, our findings indicate that CD47 blocker SIRPα-Fc enhances the antitumor efficacy of CAR-T cells and propose to block CD47/SIRPα signaling effect on CAR-T cells function, which could provide a new strategy for successful cancer immunotherapy by rationalizing combination of CD47 blocker and CAR-T cell therapy.

Dynamics of germination stimulants dehydrocostus lactone and costunolide in the root exudates and extracts of sunflower.

Orobanche cumana Wallr. (Orobanche cernua Loefl.) causes severe yield losses of confectionary sunflower in China. While germination of O. cumana is stimulated by sesquiterpene lactones (STLs) from host sunflower (Helianthus annuus L.). Dehydrocostus lactone and costunolide isolated from sunflower root exudates are known as STLs to specifically induce O. cumana germination. Two major confectionary sunflower cultivars, SH363 (highly susceptible to O. cumana) and TH33 (resistant to O. cumana), were planted in China. However, STLs in these two sunflower cultivars has remained unknown. To identify STLs from root and exudates of sunflower for better understanding the role of stimulants in parasitic interaction of sunflower and O. cumana, we tested dehydrocostus lactone (DCL) and costunolide (CL) in root and root exudates of susceptible and resistant sunflower cultivars. The stimulant activity of sunflower root exudate and root extract to germination of O. cumana were also determined. Dehydrocostus lactone and costunolide were identified through ultra-performance liquid chromatography coupled with mass spectrometry (UPLC-MS). Both DCL and CL were found in root extracts and root exudates in the whole tested time point from two sunflower cultivars. The concentration of dehydrocostus lactone was higher than that of costunolide at the same tested growth stage of each sunflower cultivar. It was observed that higher quantity of dehydrocostus lactone in susceptible cultivar than resistant cultivar of root and root exudates at later tested developmental stages. However, the amount of CL was no significant difference between SH363 and TH33 at all tested stages. The release amount of DCL from susceptible cultivar is 3.7 folds that of resistant cultivar at 28 DAT. These findings suggested that DCL was the one of the major signal compound in these two sunflower cultivars, and lower dehydrocostus lactone might contribute to the resistance of sunflower TH33 to O. cumana.

Effects of paternal exposure to cigarette smoke on sperm DNA methylation and long-term metabolic syndrome in offspring.

BACKGROUND: Although paternal exposure to cigarette smoke may contribute to obesity and metabolic syndrome in offspring, the underlying mechanisms remain uncertain. METHODS: In the present study, we analyzed the sperm DNA-methylation profiles in tobacco-smoking normozoospermic (SN) men, non-tobacco-smoking normozoospermic (N) men, and non-smoking oligoasthenozoospermic (OA) men. Using a mouse model, we also analyzed global methylation and differentially methylated regions (DMRs) of the DLK1 gene in paternal spermatozoa and the livers of progeny. In addition, we quantified DLK1 expression, executed an intra-peritoneal glucose tolerance test (IPGTT), measured serum metabolites, and analyzed liver lipid accumulation in the F1 offspring. RESULTS: Global sperm DNA-methylation levels were significantly elevated (p < 0.05) in the SN group, and the methylation patterns were different among N, SN, and OA groups. Importantly, the methylation level of the DLK1 locus (cg11193865) was significantly elevated in the SN group compared to both N and OA groups (p < 0.001). In the mouse model, the group exposed to cigarette smoke extract (CSE) exhibited a significantly higher global methylation DNA level in spermatozoa (p < 0.001) and on the DMR sites of Dlk1 in 10-week-old male offspring (p < 0.05), with a significant increase in Dlk1 expression in their livers (p < 0.001). In addition, IPGTT and LDL levels were significantly altered (p < 0.001), with elevated liver fat accumulation (p < 0.05) in F1 offspring. CONCLUSION: Paternal exposure to cigarette smoke led to increased global methylation of sperm DNA and alterations to the DMR of the DLK1 gene in the F1 generation, which may be inherited parentally and may perturb long-term metabolic function.

Amino acid substitution (Gly-654-Tyr) in acetolactate synthase (ALS) confers broad spectrum resistance to ALS-inhibiting herbicides.

BACKGROUND: Amaranthus retroflexus L. is a problematic weed in agricultural fields. In China, the repeated use of acetolactate synthase (ALS) inhibiting herbicides has led to the evolution of many A. retroflexus resistant populations. The objective of this research was to investigate the physiological and molecular basis for resistance to ALS-inhibiting herbicides in A. retroflexus. RESULTS: Sequence analysis of the ALS revealed a Trp to Leu substitution at amino acid position 574 (Trp-574-Leu), and a previously unreported substitution of Gly to Tyr substitution at 654 (Gly-654-Tyr) in the resistant A. retroflexus population. A purified R-Tyr654 subpopulation homozygous for the Gly-654-Tyr mutation was generated and characterized in response to five different classes of ALS-inhibiting herbicides. Dose-response analysis revealed that the R-Tyr654 population was highly resistant to two imidazolinones (imazethapyr, >42-fold; imazamox, 48.3-fold), one triazolopyrimidine (flumetsulam, 57.4-fold), and one sulfonylamino-carbonyltriazolinone (flucarbazone, 17.3-fold). Moreover, it was moderately resistant to two sulfonylureas (thifensulfuron-methyl, 4.9-fold; nicosulfuron, 9.1-fold), and one pyrimidinylthio-benzoate (bispyribac-sodium, 3.1-fold). An in vitro ALS activity assay showed that ALS with the Gly-654-Tyr substitution was resistant to all the tested ALS-inhibiting herbicides. However, the field rate of herbicides binding other sites of action demonstrated effective control of the R-Tyr654 population. CONCLUSION: These results indicate that the molecular basis of ALS-inhibiting herbicide resistance in A. retroflexus was caused by the Trp-574-Leu and Gly-654-Tyr substitutions in the ALS. This is the first report of Gly-654-Tyr substitution in ALS, and this substitution confers broad spectrum resistance to ALS-inhibiting herbicides. © 2021 Society of Chemical Industry.