Dataset Information

First Resistance Mechanisms Characterization in Glyphosate-Resistant Leptochloa virgata.

ABSTRACT: Leptochloa virgata (L.) P. Beauv. is an annual weed common in citrus groves in the states of Puebla and Veracruz, Mexico limiting their production. Since 2010, several L. virgata populations were identified as being resistant to glyphosate, but studies of their resistance mechanisms developed by this species have been conducted. In this work, three glyphosate-resistant populations (R8, R14, and R15) collected in citrus orchards from Mexico, were used to study their resistance mechanisms comparing them to one susceptible population (S). Dose-response and shikimic acid accumulation assays confirmed the glyphosate resistance of the three resistant populations. Higher doses of up to 720 g ae ha-1 (field dose) were needed to control by 50% plants of resistant populations. The S population absorbed between 7 and 13% more 14C-glyphosate than resistant ones, and translocated up to 32.2% of 14C-glyphosate to the roots at 96 h after treatment (HAT). The R8, R14, and R15 populations translocated only 24.5, 26.5, and 21.9%, respectively. The enzyme activity of 5-enolpyruvyl shikimate-3-phosphate synthase (EPSPS) was not different in the S, R8 and R14 populations. The R15 Population exhibited 165.9 times greater EPSPS activity. Additionally, this population showed a higher EPSPS basal activity and a substitution in the codon 106 from Proline to Serine in the EPSPS protein sequence. EPSPS gene expression in the R15 population was similar to that of S population. In conclusion, the three resistant L. virgata populations show reduced absorption and translocation of 14C-glyphosate. Moreover, a mutation and an enhanced EPSPS basal activity at target-site level confers higher resistance to glyphosate. These results describe for the first time the glyphosate resistance mechanisms developed by resistant L. virgata populations of citrus orchards from Mexico.

SUBMITTER: Alcantara-de la Cruz R

PROVIDER: S-EPMC5114308 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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First Resistance Mechanisms Characterization in Glyphosate-Resistant Leptochloa virgata.

Alcántara-de la Cruz Ricardo R Rojano-Delgado Antonia M AM Giménez María J MJ Cruz-Hipolito Hugo E HE Domínguez-Valenzuela José A JA Barro Francisco F De Prado Rafael R

Frontiers in plant science 20161118

Leptochloa virgata (L.) P. Beauv. is an annual weed common in citrus groves in the states of Puebla and Veracruz, Mexico limiting their production. Since 2010, several L. virgata populations were identified as being resistant to glyphosate, but studies of their resistance mechanisms developed by this species have been conducted. In this work, three glyphosate-resistant populations (R8, R14, and R15) collected in citrus orchards from Mexico, were used to study their resistance mecha ...[more]

PMID: 27917189

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Project description:Resistance of Chinese sprangletop (Leptochloa chinensis (L.) Nees) to the herbicide cyhalofop-butyl has recently become a severe problem in rice cultivation. However, the molecular mechanisms of target-site resistance (TSR) in cyhalofop-butyl-resistant L. chinensis as well as the underlying non-target-site resistance (NTSR) have not yet been well-characterized. This study aimed to investigate cyhalofop-butyl resistance mechanisms using one susceptible population (LC-S) and two resistant populations (LC-1701 and LC-1704) of L. chinensis. We analyzed two gene copies encoding the entire carboxyltransferase (CT) domain of chloroplastic acetyl-CoA carboxylase (ACCase) from each population. Two non-synonymous substitutions were detected in the resistant L. chinensis populations (Trp2027-Cys in the ACCase1 of LC-1701 and Leu1818-Phe in the ACCase2 of LC-1704), which were absent in LC-S. As Trp2027-Cys confers resistance to ACCase-inhibiting herbicides, the potential relationship between the novel Leu1818-Phe mutation and cyhalofop-butyl resistance in LC-1704 was further explored by single-nucleotide polymorphism (SNP) detection. Metabolic inhibition assays indicated that cytochrome P450 monooxygenases (P450s) and glutathione S-transferases (GSTs) contributed to cyhalofop-butyl resistance in specific resistant populations. RNA sequencing showed that the P450 genes CYP71Z18, CYP71C4, CYP71C1, CYP81Q32, and CYP76B6 and the GST genes GSTF11, GSTF1, and GSTU6 were upregulated in at least one resistant population, which indicated their putative roles in cyhalofop-butyl resistance of L. chinensis. Correlation analyses revealed that the constitutive or inducible expression patterns of CYP71C4, CYP71C1, GSTF1, and GSTU6 in L. chinensis were strongly associated with the resistant phenotype. For this reason, attention should be directed towards these genes to elucidate metabolic resistance to cyhalofop-butyl in L. chinensis. The findings of this study improve the understanding of mechanisms responsible for resistance to ACCase-inhibiting herbicides in grass-weed species at the molecular level, thus aiding in the development of weed management strategies that delay the emergence of resistance to this class of pest control products.

Project description:BackgroundPralatrexate (PDX) is a novel antifolate approved for the treatment of patients with relapsed/refractory peripheral T-cell lymphoma, but some patients exhibit intrinsic resistance or develop acquired resistance. Here, we evaluated the mechanisms underlying acquired resistance to PDX and explored potential therapeutic strategies to overcome PDX resistance.MethodsTo investigate PDX resistance, we established two PDX-resistant T-lymphoblastic leukemia cell lines (CEM and MOLT4) through continuous exposure to increasing doses of PDX. The resistance mechanisms were evaluated by measuring PDX uptake, apoptosis induction and folate metabolism-related protein expression. We also applied gene expression analysis and methylation profiling to identify the mechanisms of resistance. We then explored rational drug combinations using a spheroid (3D)-culture assay.ResultsCompared with their parental cells, PDX-resistant cells exhibited a 30-fold increase in half-maximal inhibitory concentration values. Induction of apoptosis by PDX was significantly decreased in both PDX-resistant cell lines. Intracellular uptake of [14C]-PDX decreased in PDX-resistant CEM cells but not in PDX-resistant MOLT4 cells. There was no significant change in expression of dihydrofolate reductase (DHFR) or folylpolyglutamate synthetase (FPGS). Gene expression array analysis revealed that DNA-methyltransferase 3β (DNMT3B) expression was significantly elevated in both cell lines. Gene set enrichment analysis revealed that adipogenesis and mTORC1 signaling pathways were commonly upregulated in both resistant cell lines. Moreover, CpG island hypermethylation was observed in both PDX resistant cells lines. In the 3D-culture assay, decitabine (DAC) plus PDX showed synergistic effects in PDX-resistant cell lines compared with parental lines.ConclusionsThe resistance mechanisms of PDX were associated with reduced cellular uptake of PDX and/or overexpression of DNMT3B. Epigenetic alterations were also considered to play a role in the resistance mechanism. The combination of DAC and PDX exhibited synergistic activity, and thus, this approach might improve the clinical efficacy of PDX.

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Dataset Information

First Resistance Mechanisms Characterization in Glyphosate-Resistant Leptochloa virgata.

Publications

First Resistance Mechanisms Characterization in Glyphosate-Resistant <i>Leptochloa virgata</i>.

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