Metabolic pathways modulated by coumarin to inhibit seed germination and early seedling growth in Eleusine indica

Coumarin is an allelochemical that is widely present in the plant kingdom and has great potential for weed control. However, its mechanisms of action remain largely unknown. This study employed metabolomic and transcriptomic analyses along with evaluations of amino acid profiles and related physiological indicators to investigate how coumarin inhibits the germination and seedling growth of Eleusine indica by modifying metabolic pathways. At 72 h of germination at 50 and 100 mg L-1 coumarin, E. indica had lower levels of soluble sugar and activities of amylases and higher levels of starch, O2-, H2O2, auxin (IAA) and abscisic acid (ABA) compared to the control. Metabolomic analysis demonstrated that coumarin treatments had a significant impact on the pathways associated with amino acid metabolism and transport and aminoacyl-tRNA biosynthesis. Exposure to coumarin induced significant alterations in the levels of 19 amino acids, with a decrease in 15 of them, including Met, Leu and γ-aminobutyric acid (GABA). Additionally, transcriptomic analysis showed that coumarin significantly disrupted several essential biological processes, including protein translation, secondary metabolite synthesis, and hormone signal transduction. The decrease in TCA cycle metabolite (cis-aconitate, 2-oxoglutarate, and malate) contents was associated with the suppression of transcription for related enzymes. Our findings indicate that the inhibition of germination and growth in E. indica by coumarin involves the suppression of starch conversion to sugars, modification of the amino acid profile, interference of hormone signalling and the induction of oxidative stress. The TCA cycle appears to be one of the most essential pathways affected by coumarin.

In vivo anthelmintic activity of Eleusine indica extracts against gastrointestinal nematodes of goats

Objective

The study aimed to determine the potential anthelmintic activity of the ethyl acetate extract of Eleusine indica that will result in an effective reduction in fecal egg per gram (EPG) counts in naturally infected goats compared to the commercial anthelmintic levamisole.

Materials and Methods

The experimental animals were 21 goats naturally infected with gastrointestinal nematodes. The goats were divided into groups that were given a single dose of E. indica extract. Five concentrations of E. indica were tested for anthelmintic activity: 100, 200, 300, 400, and 500 mg extract/kg body weight. Fecal sample collection was done before treatment, during the first treatment, and every week thereafter for 28 days post-treatment (dpt). A modified McMaster technique was used to determine the EPG of feces, and the mean efficacies of the extracts were compared with those of the commercial anthelmintic levamisole.

Results

As early as 7 dpt, there was an observed reduction in the epg counts after the administration of E. indica extracts across all concentrations. Administering 500 mg of extract/kg body weight resulted in a maximum efficacy of 56.21%. However, the efficacy achieved was lower than that of levamisole (96.83%).

Conclusion

The results show that the E. indica extract can reduce the fecal EPG counts of naturally infected goats, thus creating a potential natural anthelmintic that can be developed further.

ACCase gene mutations and P450-mediated metabolism contribute to cyhalofop-butyl resistance in Eleusine indica biotypes from direct-seeding paddy fields

Eleusine indica causes problems in direct-seeding rice fields across Jiangsu Province in China. Long-term application of chemical herbicides has led to the widespread evolution of resistance in E. indica. In this study, we surveyed the resistance level of cyhalofop-butyl (CyB) in 19 field-collected E. indica biotypes, and characterized its underlying resistance mechanisms. All 19 biotypes evolved moderate- to high-level resistance to CyB (from 5.8- to 171.1-fold). 18 biotypes had a target-site mechanism with Trp-1999-Ser, Trp-2027-Cys, or Asp-2078-Gly mutations, respectively. One biotype (JSSQ-1) was identified to have metabolic resistance, in which malathion pretreatment significantly reduced the CyB resistance, and cyhalofop acid was degraded 1.7- to 2.5-times faster in this biotype compared with a susceptible control. Furthermore, the JSSQ-1 biotype showed multiple resistance to acetyl-CoA carboxylase (ACCase) inhibitor metamifop (RI = 4.6) and fenoxaprop-p-ethyl (RI = 5.1), acetolactate synthase (ALS) inhibitor imazethapyr (RI = 4.1), and hydroxyphenylpyruvate dioxygenase (HPPD) inhibitor mesotrione (RI = 3.5). In addition, 11 out of 19 E. indica biotypes exhibited multiple resistance to glyphosate. This research has identified the widespread occurrence of CyB resistance in E. indica, attributed to target-site mutations or enhanced metabolism. Moreover, certain biotypes have exhibited resistance to multiple herbicides or even cross-resistance. Consequently, there is an urgent need to implement diverse weed management practices to effectively combat the proliferation of this weed in rice fields.

Potential Role of EPSPS Mutations in the Resistance of Eleusine indica to Glyphosate

Gene mutation is a basic evolutionary mechanism in plants under selection pressure of herbicides. Such mutation has pleiotropic effects on plant growth. We systemically investigated the effects of Pro106Leu (P106L), Pro106Ser (P106S), and Thr102Ile + Pro106Ser (TIPS) mutations on EPSPS functionality and fitness traits in Eleusine indica at the biochemical and physiological levels. The affinity of natural EPSPS for glyphosate was 53.8 times higher than that for phosphoenolpyruvate (PEP), as revealed by the dissociation constant; the constant decreased in both the P106L (39.9-fold) and P106S (46.9-fold) mutants but increased in the TIPS (87.5-fold) mutant. The Km (PEP) values of the P106L, P106S, and TIPS mutants were 2.4-, 0.7-, and 4.1-fold higher than that of natural EPSPS, corresponding to resistance levels of 2.5, 1.9, and 11.4, respectively. The catalytic efficiency values (maximum reaction rates) were 0.89-, 0.94-, and 0.26-fold higher than that of natural EPSPS. The levels of metabolites related to amino acids and nucleotides were significantly reduced in the mutated plants. The fitness costs were substantial for the biomass, total leaf area, seed number, and seedling emergence throughout the growth period in the plants with P106L and TIPS mutations. These results provide insights into EPSPS kinetics and their effect on plant growth.

EST-SSR Markers' Development Based on RNA-Sequencing and Their Application in Population Genetic Structure and Diversity Analysis of Eleusine indica in China

Goosegrass (Eleusine indica) is one of the worst agricultural weeds in China. Molecular markers were developed for genetic diversity and population structure analyses. In this study, we identified 8391 expressed sequence tag-simple sequence repeat (EST-SSR) markers from the de novo assembled unigenes of E. indica. Mononucleotides were the most abundant type of repeats (3591, 42.79%), followed by trinucleotides (3162, 37.68%). The most dominant mononucleotide and trinucleotide repeat motifs were A/T (3406, 40.59%) and AAT/ATT (103, 1.5%), respectively. Fourteen pairs of EST-SSR primers were verified and used to analyze the genetic diversity and population structure of 59 goosegrass populations. A total of 49 alleles were amplified, with the number of alleles (N_a) ranging from two to eleven per locus, and the effective number of alleles (N_e) ranged from 1.07 to 4.53. The average polymorphic information content (PIC) was 0.36. Genetic structure analysis (K = 2) and principal coordinate analysis divided 59 E. indica populations into two groups in a manner similar to the unweighted pair-group method (Dice genetic similarity coefficient = 0.700). This study developed a set of EST-SSR markers in E. indica and successfully analyzed the diversity and population genetic structures of 59 E. indica populations in China.

Multiple Resistance Mechanisms Involved in Glyphosate Resistance in Eleusine indica

Glyphosate is a non-selective herbicide and is widely used for weed control in non-cultivated land in China. One susceptible (S) and five putative glyphosate-resistant (R1, R2, R3, R4, and R5) Eleusine indica biotypes were selected to investigate their resistance levels and the potential resistance mechanisms. Based on the dose-response assays, the R3 and R5 biotypes showed a low-level (2.4 to 3.5-fold) glyphosate resistance, and the R1, R2, and R4 biotypes exhibited a moderate- to high-level (8.6 to 19.2-fold) resistance, compared with the S biotype. The analysis of the target-site resistance (TSR) mechanism revealed that the P106A mutation and the heterozygous double T102I + P106S mutation were found in the R3 and R4 biotypes, respectively. In addition, the similar EPSPS gene overexpression was observed in the R1, R2, and R5 biotypes, suggesting that additional non-target-site resistance (NTSR) mechanisms may contribute to glyphosate resistance in R1 and R2 biotypes. Subsequently, an RNA-Seq analysis was performed to identify candidate genes involved in NTSR. In total, ten differentially expressed contigs between untreated S and R1 or R2 plants, and between glyphosate-treated S and R1 or R2 plants, were identified and further verified with RT-qPCR. One ATP-binding cassette (ABC) transporter gene, one aldo-keto reductases (AKRs) gene and one cytochrome P450 monooxygenase (CytP450) gene were up-regulated in R1 or R2 plants. These results indicated that EPSPS overexpression, single or double mutation was a common TSR mechanisms in E. indica. Additional NTSR mechanisms could play an essential role in glyphosate resistance. Three genes, ABCC4, AKR4C10, and CYP88, could serve as important candidate genes and deserve further functional studies.

Evolution of competitive traits changes species diversity in a natural field

Studying the interaction between evolutionary and ecological processes (i.e. eco-evolutionary dynamics) has great potential to improve our understanding of biological processes such as species interactions, community assembly and ecosystem functions. However, most experimental studies have been conducted under controlled laboratory or mesocosm conditions, and the importance of these interactions in natural field communities has not been evaluated. In this study, we focused on the contemporary divergence of a competitive trait (the height-width ratio) of an annual grass Eleusine indica between urban and farmland populations and investigated how trait evolution affects ecological processes by transplanting E. indica individuals from lineages with different trait values into semi-natural grassland. The competitive trait of the transplanted individuals not only affected their own growth and fitness, but also affected the vegetative growth of the competing species and the species diversity. These results indicate that the evolution of competitive traits, even in a single species, can influence the community species diversity through changes in interspecific interactions. Eco-evolutionary interactions therefore play a crucial role in natural field environments. Our results suggest that understanding intraspecific variation in competitive traits driven by rapid evolution is essential for understanding interspecific competitive interactions, community assembly and species diversity.

Multiple herbicide resistance in Eleusine indica from sugarcane fields in China

Long-term reliance on herbicide weed control has led to resistance evolution in Eleusine indica in sugarcane fields of Guangxi Zhuang autonomous region. Ninety-six E. indica lines were collected from this region, and their response was tested to six herbicides: glyphosate; glufosinate; PSII-inhibitors diuron and atrazine; and PSI inhibitors paraquat and diquat. Target-site resistance mechanisms were examined in specific lines with multiple resistance to three herbicide modes of action. Of 96 E. indica lines, 51, 26, and 24 lines had resistance to diuron, atrazine, and diquat, respectively, while 14 and 9 had resistance to paraquat and glyphosate. Among 25 lines tested with multiple resistance, 7 lines exhibited resistance to three herbicide modes of action. In two multiple resistant lines (GXER2, GXER5), amplification/over-expression/mutations of the EPSPS gene contributed to the very high-level (up to 109-fold) glyphosate resistance. No target-site mutations/over-expression were identified in the psbA gene in these two lines, so non-target-site resistance mechanisms were likely responsible for the low-level (3-fold) resistance to the PSII herbicides diuron and atrazine. A high-level (23-fold) of paraquat resistance was observed in GXER5, and a low-level (5-fold) paraquat resistance was found in GXER2. Multiple herbicide resistance in E. indica has evolved in sugarcane fields of Guangxi Zhuang autonomous region with diverse resistance mechanisms. Therefore, diversified weed control tactics should be adopted to prevent this weed.

Identification of two Eleusine indica (goosegrass) biotypes of cool-season turfgrass resistant to dithiopyr

BACKGROUND

Turfgrass managers reported poor Eleusine indica control following applications of the mitosis-inhibiting herbicide dithiopyr in cool-season turfgrass. Field, glasshouse, and laboratory experiments were conducted to understand the response of these biotypes to dithiopyr and prodiamine.

RESULTS

In field experiments at two locations with putative dithiopyr-resistant E. indica, preemergence applications of dithiopyr provided no E. indica control. Single applications of the protoporphyrinogen oxidase (PPO)-inhibitor, oxadiazon, provided > 85% control at these locations. When subjected to agar-based bioassays, root growth of putative resistant biotypes planted with 0.01 mmol L^-1 dithiopyr was slightly reduced (< 25%) whereas roots were completely inhibited in the susceptible biotype. Glasshouse whole plant rate-response experiments found that the cytochrome P450 inhibitor, piperonyl butoxide (PBO), did not increase the sensitivity of these putative resistant biotypes to dithiopyr. Sequencing of α-tubulin 1 (TUA1) revealed a Leu-136-Phe substitution in both dithiopyr-resistant populations.

CONCLUSION

Eleusine indica biotypes with resistance to dithiopyr are present in cool-season turfgrass systems in the United States. Resistance is possibly related to a single nucleotide polymorphism (SNP) of an α-tubulin gene. If turfgrass managers suspect resistance to dithiopyr, oxadiazon can still be an effective alternative for preemergence control. © 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Evolution of multiple target-site resistance mechanisms in individual plants of glyphosate-resistant Eleusine indica from China

BACKGROUND

Glyphosate has been used for weed control in South China in various situations for four decades, and most Eleusine indica populations are suspected to have evolved resistance to glyphosate. This research investigated underling target-site glyphosate resistance mechanisms in six field-collected, putative glyphosate-resistant (R) E. indica populations.

RESULTS

The six R E. indica populations were confirmed to be low (1.8 to 2.6-fold) to moderately (5.6- to 8.4-fold) resistant to glyphosate relative to the susceptible (S) population. Sixty-seven glyphosate-surviving plants from the six R populations were used to examine target-site resistance mechanisms. Target-site 5-enolpyruvylshikimate3-phosphate synthase (EPSPS) overexpression (OE) (plus further induction by glyphosate treatment) and gene copy number variation (CNV) occurred in 94% R plants, and among them, 16% had the P106A mutation and 49% had the heterozygous double TIPS (T102I + P106S) mutation (plus P381L). In addition, a low number of R plants (6%) only had the homologous TIPS (plus P381L) mutation. The (CT)6 insertion mutation in the EPSPS 5†-UTR always associates with EPSPS OE and CNV. Progeny plants possessing EPSPS OE/CNV (and P106A) displayed low level (up to 4.5-fold) glyphosate resistance. In contrast, plants homozygous for the TIPS mutation displayed higher (25-fold) resistance to glyphosate and followed by plants heterozygous for this mutation plus EPSPS OE/CNV (12-fold).

CONCLUSIONS

Target-site glyphosate resistance in E. indica populations from South China is common with prevalence of EPSPS OE/induction/CNV conferring low level resistance. Individual plants acquiring both the TIPS mutation and EPSPS OE/CNV are favored due to evolutionary advantages. The role of (CT)6 insertion mutation in EPSPS CNV is worth further investigation. © 2021 Society of Chemical Industry.

Detection of subgenome bias using an anchored syntenic approach in Eleusine coracana (finger millet)

Background

Finger millet (Eleusine coracana 2n = 4x = 36) is a hardy, nutraceutical, climate change tolerant, orphan crop that is consumed throughout eastern Africa and India. Its genome has been sequenced multiple times, but A and B subgenomes could not be separated because no published genome for E. indica existed. The classification of A and B subgenomes is important for understanding the evolution of this crop and provide a means to improve current and future breeding programs.

Results

We produced subgenome calls for 704 syntenic blocks and inferred A or B subgenomic identity for 59,377 genes 81% of the annotated genes. Phylogenetic analysis of a super matrix containing 455 genes shows high support for A and B divergence within the Eleusine genus. Synonymous substitution rates between A and B genes support A and B calls. The repetitive content on highly supported B contigs is higher than that on similar A contigs. Analysis of syntenic singletons showed evidence of biased fractionation showed a pattern of A genome dominance, with 61% A, 37% B and 1% unassigned, and was further supported by the pattern of loss observed among cyto-nuclear interacting genes.

Conclusion

The evidence of individual gene calls within each syntenic block, provides a powerful tool for inference for subgenome classification. Our results show the utility of a draft genome in resolving A and B subgenomes calls, primarily it allows for the proper polarization of A and B syntenic blocks. There have been multiple calls for the use of phylogenetic inference in subgenome classification, our use of synteny is a practical application in a system that has only one parental genome available.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-07447-y.

A novel mutation A212T in chloroplast Protoporphyrinogen oxidase (PPO1) confers resistance to PPO inhibitor Oxadiazon in Eleusine indica

BACKGROUND

Protoporphyrinogen oxidase (PPO) with two isoforms, chloroplast-targeted (PPO1) and mitochondrial-targeted (PPO2), catalyzes a step in the biosynthesis of chlorophyll and heme. PPO1 and PPO2 are herbicide target sites of PPO-inhibiting herbicides. Target-site mutations conferring resistance to PPO inhibitors have all thus far been in PPO2. Oxadiazon is a unique PPO inhibitor utilized for preemergence Eleusine indica control. In this research, we evaluated the response of two previously confirmed oxadiazon-resistant and susceptible E. indica biotypes to other PPO inhibitors and identified the resistance mechanism in two oxadiazon-resistant E. indica biotypes.

RESULTS

Two E. indica biotypes were resistant to oxadiazon, but not to other structurally unrelated PPO inhibitors, such as lactofen, flumioxazin and sulfentrazone. A novel mutation A212T was identified in the chloroplast-targeted PPO1, conferring resistance to oxadiazon in a heterologous expression system. Computational structural modeling provided a mechanistic explanation for reduced herbicide binding to the variant protein: the presence of a methyl group of threonine 212 changes the PPO1 active site and produces repulsive electrostatic interactions that repel oxadiazon from the binding pocket.

CONCLUSION

The novel A212T mutation in PPO1 conferring resistance specifically to PPO inhibitor oxadiazon was characterized. This is the first evidence of the direct role of PPO1 in the PPO mode of action, and the first evidence of evolved resistance in PPO1. © 2019 Society of Chemical Industry.

Cyhalofop-butyl and Glyphosate Multiple-Herbicide Resistance Evolved in an Eleusine indica Population Collected in Chinese Direct-Seeding Rice

Eleusine indica is a typical xerophytic weed species with a cosmopolitan distribution. It is invasive and highly adaptable to diverse habitats and crops. Due to rice cropping-pattern changes, E indica has become one of the main dominant grass weeds infecting direct-seeding paddy fields. A Chinese E. indica population has evolved multiple-herbicide resistance to cyhalofop-butyl and glyphosate. In this study, the multiple-resistance profile of E. indica to these two different types of herbicides and their resistance mechanisms were investigated. Whole-plant dose-response assays indicated that the multiple-herbicide-resistant (MHR) population exhibited 10.8-fold resistance to cyhalofop-butyl and 3.1-fold resistance to glyphosate compared with the susceptible (S) population. ACCase sequencing revealed that the Asp-2078-Gly mutation was strongly associated with E. indica resistance to cyhalofop-butyl. The MHR plants accumulated less shikimic acid than S plants at 4, 6, and 8 days after glyphosate treatment. In addition, no amino acid substitution in the EPSPS gene was found in MHR plants. Further analysis revealed that the relative expression level of EPSPS in MHR plants was 6-10-fold higher than that in S plants following glyphosate treatment, indicating that EPSPS overexpression may contribute to the glyphosate resistance. Furthermore, the effectiveness of nine post-emergence herbicides against E. indica were evaluated, and one PPO inhibitor pyraclonil was identified as highly effective in controlling the S and MHR E. indica populations.

Alterations in the 5' untranslated region of the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene influence EPSPS overexpression in glyphosate-resistant Eleusine indica

BACKGROUND

The herbicide glyphosate inhibits the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). Overexpression of the EPSPS gene is one of the molecular mechanisms conferring glyphosate resistance in weeds, but the transcriptional regulation of this gene is poorly understood. The EPSPS gene was found to be significantly up-regulated following glyphosate treatment in a glyphosate-resistant Eleusine indica population from southern China. To further investigate the regulation of EPSPS overexpression, the promoter of the EPSPS gene from this E. indica population was cloned and analyzed.

RESULTS

Two upstream regulatory sequences, Epro-S (862 bp) and Epro-R (877 bp), of EPSPS were obtained from glyphosate-susceptible (S) and -resistant (R) E. indica plants, respectively, by high-efficiency thermal asymmetric interlaced polymerase chain reaction (HiTAIL-PCR). The Epro-S and Epro-R sequences were 99% homologous, except for two insertions (3 and12 bp) in the R sequence. The 12-base insertion in the Epro-R sequence was located in the 5' untranslated region (UTR) pyrimidine nucleotide-rich (Py-rich) stretch element. Promoter activity tests showed that the 12-base insertion resulted in significant enhancement of Epro-R promoter activity, whereas the 3-base insertion had little effect on Epro-R promoter activity.

CONCLUSION

Alterations in the 5' UTR Py-rich stretch element of EPSPS are responsible for glyphosate-induced EPSPS overexpression. Thus, EPSPS transcriptional regulation confers glyphosate resistance in this E. indica population. © 2018 Society of Chemical Industry.

Characterization of Eleusine indica with gene mutation or amplification in EPSPS to glyphosate

The evolution of weed-resistant species threatens the sustainable use of glyphosate, which is the most important herbicide widely used in agriculture worldwide. Moreover, the high glyphosate resistance (>180-fold based on LD50) of Eleusine indica found in Malaysia, which carries a double mutation in its 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), made the control of this species more difficult. By contrast, the same species carrying the same double mutation in EPSPS (T102I+P106S) but found in China only shows a resistance level of not more than 14-fold based on GR50. The resistance level of this population is four times higher than that of the population carrying a single mutation (P106L). Although the members of this population survive under a high glyphosate dosage of 10,080gaeha-1, their growth was significantly inhibited by glyphosate under the recommend dose (840gaeha-1), where in the fresh weight was 85.4% of the control. EPSPS expression, relative copy number, and EPSPS activity in this population were similar to those of the susceptible population. In addition, the expression of two glutathione transferase (GST) genes (GST-U8 and GST-23) and the enzyme activity of the GST in this population did not significantly differ from those of the susceptible population. This finding is important in elucidating the resistance of the naturally evolved glyphosate-resistant (GR) weed species carrying a double mutation in EPSPS to glyphosate.

Characterisation of glufosinate resistance mechanisms in Eleusine indica

BACKGROUND

An Eleusine indica population has evolved resistance to glufosinate, a major post-emergence herbicide of global agriculture. This population was analysed for target-site (glutamine synthetase) and non-target-site (glufosinate uptake, translocation and metabolism) resistance mechanisms.

RESULTS

Glutamine synthetase (GS) activity extracted from susceptible (S) and resistant (R*) plants was equally sensitive to glufosinate inhibition, with IC₅₀ values of 0.85 mm and 0.99 mm, respectively. The extractable GS activity was also similar in S and R* samples. Foliar uptake of [¹⁴ C]-glufosinate did not differ in S and R* plants, nor did glufosinate net uptake in leaf discs. Translocation of [¹⁴ C]-glufosinate into untreated shoots and roots was also similar in both populations, with 44% to 47% of the herbicide translocated out from the treated leaf 24 h after treatment. The HPLC and LC-MS analysis of glufosinate metabolism revealed no major metabolites in S or R* leaf tissue.

CONCLUSIONS

Glufosinate resistance in this resistant population is not due to an insensitive GS, or increased activity, or altered glufosinate uptake and translocation, or enhanced glufosinate metabolism. Thus, target-site resistance is likely excluded and the exact resistance mechanism(s) remain to be determined. © 2017 Society of Chemical Industry.

Potential Lipid-Lowering Effects of Eleusine indica (L) Gaertn. Extract on High-Fat-Diet-Induced Hyperlipidemic Rats

Background:

To date, anti-obesity agents based on natural products are tested for their potential using lipase inhibition assay through the interference of hydrolysis of fat by lipase resulting in reduced fat absorption without altering the central mechanisms. Previous screening study had indicated strong anti-obesity potential in Eleusine indica (E. indica), but to date, no pharmacologic studies have been reported so far.

Objective:

This study was performed to investigate the lipid-lowering effects of E. indica using both in vitro and in vivo models.

Methods:

The crude methanolic extract of E. indica was fractionated using hexane (H-Ei), dichloromethane (DCM-Ei), ethyl acetate (EA-Ei), butanol (B-Ei), and water (W-Ei). All the extracts were tested for antilipase activity using porcine pancreatic lipase. Because H-Ei showed the highest inhibition, it was further subjected to chemical profiling using high-performance liquid chromatography. Subsequently, oral toxicity analysis of H-Ei was performed [Organization for Economic Cooperation and Development guidelines using fixed dose procedure (No. 420)]; efficacy analysis was performed using high-fat diet (HFD)-induced hyperlipidemic female Sprague–Dawley rats.

Results:

According to the toxicity and efficacy analyses, H-Ei did not demonstrate any noticeable biochemical toxicity or physiologic abnormalities and did not cause any tissue damage as per histologic analysis. Furthermore, H-Ei significantly reduced body weight and improved serum profile and did not show hepatotoxicity and nephrotoxicity based on the serum profile. Moreover, H-Ei alleviated HFD-induced hepatosteatosis and ameliorated induced adiposity in both visceral and subcutaneous adipose tissue.

Conclusion:

Our results demonstrate that H-Ei effectively improved hyperlipidemia. Further studies to explore its possibility as an alternative pharmacologic agent to treat obesity are warranted.

SUMMARY

Hexane extract of Eleusine indica (H-Ei) showed strong potential in the inhibition of porcine pancreatic lipase (27.01 ± 5.68%).

The acute oral toxicity of E. indica hexane extract on animal model falls into Globally Harmonized System Category 5 (low hazard), since mortality, clinical toxicity symptoms, gross pathologic, or histopathologic damage was not observed.

The hexane extract of E. indica had significantly reduced the body weight and improved serum lipid profile, with reduction in serum triglycerides, total cholesterol, low-density lipoprotein, and elevation in high-density lipoprotein when comparing against the high-fat diet control group.

Microscopic evaluation on histologic slides of liver and adipose tissues suggested that E. indica hexane extract had greatly improved liver steatosis and adipose tissue hypertrophy in high-fat diet control group.

Abbreviation used: ALT: Alanine transaminase; AST: Aspartate transaminase; B-Ei: Butanol extract of E. indica; DCM-Ei: Dichloromethane extract of E. indica; EA-Ei: Ethyl acetate extract of E. indica; GHS: Globally Harmonized System; HDL: High-density lipoprotein; H-Ei: Hexane extract of E. indica; HFD: High-fat diet; HPLC: High-performance liquid chromatography; LDL: Low-density lipoprotein; NFD: Normal fed diet; PPL: Porcine pancreatic lipase; SEM: Standard error of mean; SD: Standard deviation; TC: Total cholesterol; TG: Triglycerides; W-Ei: Water extract of E. indica.

Emergence of wheat blast in Bangladesh was caused by a South American lineage of Magnaporthe oryzae

BACKGROUND

In February 2016, a new fungal disease was spotted in wheat fields across eight districts in Bangladesh. The epidemic spread to an estimated 15,000 hectares, about 16 % of the cultivated wheat area in Bangladesh, with yield losses reaching up to 100 %. Within weeks of the onset of the epidemic, we performed transcriptome sequencing of symptomatic leaf samples collected directly from Bangladeshi fields.

RESULTS

Reinoculation of seedlings with strains isolated from infected wheat grains showed wheat blast symptoms on leaves of wheat but not rice. Our phylogenomic and population genomic analyses revealed that the wheat blast outbreak in Bangladesh was most likely caused by a wheat-infecting South American lineage of the blast fungus Magnaporthe oryzae.

CONCLUSION

Our findings suggest that genomic surveillance can be rapidly applied to monitor plant disease outbreaks and provide valuable information regarding the identity and origin of the infectious agent.

Susceptibility of Several Common Subtropical Weeds to Meloidogyne arenaria, M. incognita, and M. javanica

Experiments were conducted in the greenhouse to assess root galling and egg production of three root-knot nematode species, Meloidogyne arenaria, M. incognita, and M. javanica, on several weeds common to Florida agricultural land. Weeds evaluated were Amaranthus retroflexus (redroot pigweed), Cyperus esculentus (yellow nutsedge), Eleusine indica (goosegrass), Portulaca oleracea (common purslane), and Solanum americanum (American black nightshade). Additionally, although it is recommended as a cover crop in southern regions of the U.S., Aeschynomene americana (American jointvetch) was evaluated as a weed following the detection of root galling in a heavy volunteer infestation of an experimental field in southeastern Florida. Weeds were propagated from seed and inoculated with 1000 nematode eggs when plants reached the two true-leaf stage. Tomato (Solanum lycopersicum 'Rutgers') was included as a positive control. Aeschynomene americana and P. oleracea roots supported the highest number of juveniles (J2) and had the highest number of eggs/g of root for all three species of Meloidogyne tested. However, though P. oleracea supported very high root levels of the three nematode species tested, its fleshy roots did not exhibit severe gall symptoms. Low levels of apparent galling, combined with high egg production, increase the potential for P. oleracea to support populations of these three species of root-knot nematodes to a degree that may not be appropriately recognized. This research quantifies the impact of P. oleracea as a host for M. arenaria, M. incognita, and M. javanica compared to several other important weeds commonly found in Florida agricultural production, and the potential for A. americana to serve as an important weed host of the three species of root-knot nematode tested in southern regions of Florida.

Host Status of Seven Weed Species and Their Effects on Ditylenchus destructor Infestation of Peanut

The host suitability to Ditylenchus destructor of seven common weed species in peanut (Arachis hypogaea) fields in South Africa was determined. Based on the number of nematodes per root unit, white goosefoot (Chenopodium album), feathertop chloris (Chloris virgata), purple nutsedge (Cyperus rotundus), jimson weed (Datura stramonium), goose grass (Eleusine indica), khaki weed (Tagetes minuta), and cocklebur (Xanthium strumarium) were poor hosts. Ditylenchus destructor survived on all weed species; population densities increased in peanut hulls and caused severe damage to seeds of peanut grown after weeds. Roots of purple nutsedge left in the soil suppressed populations of D. destructor and root and pod development in peanut grown after the weed. However, nematode populations in peanut hulls and seeds were not suppressed. Some weed species, especially purple nutsedge which is common in peanut fields, can be used to indicate the presence of D. destructor in the absence of peanut.

Host Status of Five Weed Species and Their Effects on Pratylenchus zeae Infestation of Maize

The host suitability of five of the most common weed species occurring in maize (Zea mays L.) fields in South Africa to Pratylenchus zeae was tested. Based on the number of nematodes per root unit, mealie crotalaria (Crotalaria sphaerocarpa) was a good host; goose grass (Eleusine indica), common pigweed (Amaranthus hybridus), and thorn apple (Datura stramonium) were moderate hosts; and khaki weed (Tagetes minuta) was a poor host. Only the root residues of khaki weed suppressed the P. zeae infestation of subsequently grown maize. When goose grass, khaki weed, and mealie crotalaria were grown in association with maize in soil infested with P. zeae, goose grass and khaki weed severely suppressed maize root development; this resulted in a low number of nematodes per maize root system and a high number of nematodes per maize root unit. Mealie crotalaria did not restrict maize root growth and did not affect nematode densities per maize root system or maize root unit. Special attention should be given to the control of mealie crotalaria, which is a good host for P. zeae, and goose grass, which, in addition to its ability to compete with maize, is also a suitable host for P. zeae.