Shikimic Acid Levels Research Articles

Improving sugar and respiratory metabolism in pear wounds by postharvest dipping with chitosan and chitooligosaccharide

Chitosan (CTS) and its degradation product, chitooligosaccharide (COS), promote fruit healing by activating phenylpropanoid metabolism. This study investigates their effects on sucrose metabolism in pear wounds. CTS and COS were found to activate neutral invertase, acid invertase, sucrose synthase, and sucrose phosphate synthase, increasing sucrose, glucose, and fructose levels in fruit wounds. They also enhanced sorbitol dehydrogenase activity and promoted sorbitol accumulation. In addition, CTS and COS improved the activities of hexokinase, phosphofructokinase, and pyruvate kinase, increasing phosphoenolpyruvate and ATP production. They activated glucose-6-phosphate dehydrogenase and increased erythrose-4-phosphate, NADPH, and shikimic acid levels. In conclusion, CTS and COS support the formation of the healing closing layer by supplying carbon skeletons, energy, and reducing power through the activation of sugar and respiratory metabolism during the healing process. Compared to CTS, COS was superior in activating the above metabolisms, which is expected to be widely used as a chitin product in postharvest fruit and vegetable preservation and provide new insights into preserving pear freshness.

Metabolomics characterizes early metabolic changes and markers of tolerant Eucalyptus ssp. clones against drought stress

EucalyptusL’Hér. (Myrtaceae) is one of the economically most important and widely cultivated trees for wood crop purposes worldwide. Climatic changes together with the constant need to expand plantations to areas that do not always provide optimal conditions for plant growth highlight the need to assess the impact of abiotic stresses on eucalypt trees. We aimed to unveil the drought effect on the leaf metabolome of commercial clones with differential phenotypic response to this stress. For this, seedlings of 13 clones were grown at well-watered (WW) and water-deficit (WD) conditions and their leaf extracts were subjected to comparative analysis using ultra-high performance liquid chromatography coupled to mass spectrometry (UPLC-MS) and nuclear magnetic resonance spectroscopy (NMR). UPLC-MS and NMR analyses led to the annotation of over 100 molecular features of classes such as cyclitols, phenolics, flavonoids, formylated phloroglucinol compounds (FPCs) and fatty acids. Multivariate data analysis was employed for specimens' classifications and markers identification from both platforms. The results obtained in this work allowed us to classify clones differing in drought tolerance. Classification models were validated using an extra subset of samples. Tolerant plants exposed to water deficit accumulated arginine, gallic acid derivatives, caffeic acid and tannins at higher levels. In contrast, stressed drought-sensitive clones were characterised by a significant reduction in glucose, inositol and shikimic acid levels. These changes in contrasting drought response eucalypt pave ways for differential outcomes of tolerant and susceptible phenotypes. Under optimal growth conditions, all clones were rich in FPCs. These results can be used for early screening of tolerant clones and to improve our understanding of the role of these biomarkers in Eucalyptus tolerance to drought stress.

Effects of pre-harvest glyphosate use on protein composition and shikimic acid accumulation in spring wheat.

During wheat cultivation, glyphosate-based herbicides are recommended to be applied a week prior to harvest during the ripe stage of physiological maturity. However, some grains may not be at this physiological stage due to non-uniform maturation within the field. The goal of this study was to determine the effect of glyphosate-based herbicide timing on the chemistry of wheat gluten proteins and shikimic acid accumulation. The results of the study indicate that pre-harvest glyphosate application does not impact the amino acid composition, protein secondary structure or gluten protein composition. However, pre-harvest glyphosate application decreased the molecular weight of SDS extractable and unextractable proteins, and significantly increased the amount of shikimic acid accumulation, especially when applied early. Thus, this study indicates that pre-harvest use of glyphosate-based herbicides can cause significant differences in wheat protein chemistry and shikimic acid levels, especially when applied earlier than recommended, emphasizing the importance of timely application.

A modified in-planta transformation technique to generate stable gain-in function transformants in a recalcitrant indica rice genotype

A tissue culture independent in-planta transformation technique is an alternate option to generate transgenics in crop cultivars recalcitrant for regeneration. The T0 plants generated by in-planta technique are chimeric hence very large number of T1 seeds needs to be screened to identify the putative transformants. Besides, low transformation efficiency and stable integration is another lacuna, because the T0 seedling explants are not subjected for selection. To overcome these constraints, a modified in-planta technique was developed in this study to generate gain-in-function activation tagged mutants in the background of a recalcitrant rice genotype, KMP-153. A binary vector was developed with three glyphosate selectable marker genes and 4X CaMV 35S enhancer elements for developing rice plants. Simultaneous expression of Glyphosate insensitive CP4-EPSPS with two other glyphosate degrading enzymes, PsAKR1 (Aldo–Keto reductases) and GO (Glycine Oxidase) substantially improved tolerance up to 100 ppm of glyphosate in the seedling bioassay system. Selecting the seedling explants and T1 generation seeds at higher concentration (100 ppm) of glyphosate resulted in recovering fewer transformants but with stable integration and expression of all the transgenes compared to those screened at lower levels of glyphosate. Further, T2 generation plants from these transgenic lines grown in contained nethouse conditions were tolerant when sprayed up to 1500 ppm concentrations of glyphosate. These transgenics showed substantial lower levels of shikimic acid compared to wild type plants treated with glyphosate signifies the expression of the transgenes and less inhibition of shikimic acid pathway by glyphosate. The proteins extracted from the transgenic plants showed significant degradation of glyphosate. The stable integration was confirmed through flanking sequence information and event specific PCR information. Our results clearly demonstrate that the modified in-planta technique is a potential transformation protocol to generate stable transformants in rice cultivars.

Glyphosate on shikimic acid on Urochloa plantaginea

ABSTRACT: Shikimic acid (SA) has witnessed a strong increase in recent years due to the increasing demand of the pharmaceutical and cosmetic industry. The SA is used as a precursor for the synthesis of oseltamivir phosphate (Tamiflu®), a potent viral inhibitor and is extracted from the plant Illicium verum Hook which has a limited availability. This article proposed the use of Urochloa plantaginea (Link.) webster and glyphosate, as an alternative source of SA. U. plantaginea plants with 3 - 4 tillers and 4 - 6 leaves were harvest at 3, 6, 9 and 12 days after application (DAT) of low rates of glyphosate. Samples were dried, extracted, analyzed by HPLC and LC-MS/MS. The maximum SA concentrations were observed at 6 days after glyphosate at 36 g.a.e.ha-1 was applied in plants of U. plantaginea with 4 to 6 leaves. The capability of this annual gramineae to produce elevated SA levels throughout the entire biomass affords its potential for a greater yield on a per hectare basis.

Pressurized Hot Water Extraction and Capillary Electrophoresis for Green and Fast Analysis of Useful Metabolites in Plants.

The search for useful compounds from plants is an important research area. Traditional screening that involves isolation and identification/quantitation is tedious, time consuming, and generates a significant amount of chemical waste. Here, we present a simple, fast, and green strategy to assess ≥0.1% wt/wt quantities of useful compounds in plants/spices using pressurized hot water extraction using a household espresso machine followed by chemical analysis using capillary electrophoresis. Three demonstrations with polygodial, cinnamaldehyde, coumarin, and shikimic acid as target metabolites are shown. Direct analysis of extracts was by the developed micellar electrokinetic chromatography and capillary zone electrophoresis methods. The approach, which can be implemented in less developed countries, can process many samples within a day, much faster than traditional techniques that would normally take at least a day. Finally, 0.8–1.1% wt/wt levels of shikimic acid were found in Tasmanian-pepperberry and Tasmanian-fuschia leaves via the approach.

Growth-stage and temperature influence glyphosate resistance in Conyza bonariensis (L.) Cronquist

Glyphosate, currently the world's most extensively used herbicide was on the market for more than 20 years since its introduction in 1975 without reported evolution of resistant weed cases. Glyphosate is the only reported herbicide to inhibit 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), and endogenous accumulation of shikimic acid has been used as a biomarker for the herbicide's activity in plants after spraying. Increased levels of shikimic acid indicate sensitivity or injury while a lack or limited accumulation of shikimic acid shows resistance to glyphosate. Conyza bonariensis seed germinates in flushes in South Africa and its emergence is staggered throughout the year under conducive temperature conditions. This variability in growth stages in the same field poses a challenge in chemical control. Glyphosate herbicide efficacy is affected by environmental conditions, particularly temperature. A glyphosate resistance screening study was carried out based on reports from farmers that C. bonariensis has become increasingly difficult to control especially in conservation tillage systems. This study has confirmed the occurrence of glyphosate-resistant C. bonariensis (hairy fleabane) cases in the western and southern Cape regions of South Africa. A glasshouse screening experiment of 24 biotypes indicates resistance levels ranging from 0.6 to 26.9-fold, with GR50 values of up to 3908.42 g.ae.ha−1 being reported in a population collected from a vineyard in the Piketberg district of the western Cape. The influence of growth stage and temperature on glyphosate resistance in hairy fleabane was evaluated by using a shikimate assay. Results from this study have shown that response of hairy fleabane to glyphosate is influenced by the phenological stage, with sensitivity or injury decreasing with growth stage. The significant statistical tests verified the dependence of the shikimate pathway on temperature, with more shikimic acid accumulating at 15 °C compared to 27 °C across all biotypes, regardless of origin and glyphosate tolerance status. More tolerance to the herbicide was demonstrated under warm temperature conditions. Possible outcomes of applying glyphosate at the bolting stage and under warm temperature conditions are escapes and no control of susceptible and resistant plants, respectively.

Effect of the A-Type Linkage on the Pharmacokinetics and Intestinal Metabolism of Litchi Pericarp Oligomeric Procyanidins.

The bioavailability of A-type procyanidins in vivo has been rarely investigated; as such, this study discusses the effect of A-type linkage and degree of polymerization on the metabolism of procyanidins extracted from litchi pericarp (LPOPC). Sprague-Dawley rats were gavaged with (-)-epicatechin (EC) and LPOPC and sacrificed at different time points after ingestion. A-type linkage procyanidin oligomers inhibited the absorption of EC. Analysis of urinary contents from rats administered with EC, A-type procyanidin dimer (A-2), and A-type procyanidin trimer (A-3) showed distinct native and metabolite profiles for each rat. Rats fed with A-2 and A-3 presented significantly higher levels of shikimic acid and less amount of m(p)-coumaric acid metabolites in vivo and provide insight into the quantitative structure-activity relationship of procyanidin oligomers during metabolism, indicating that procyanidins with A-type linkage could induce an altered metabolic pathway of oligomers in the gastrointestinal system.

An Alternative Method to Produce Shikimic Acid Chemical Feedstock by Applying Glyphosate to Forage Crops

Shikimic acid is the critical precursor to manufacture the antiviral drug Oseltamivir phosphate, also known as Tamiflu. Current sources of shikimic acid feedstock have been strained during pandemic influenza outbreaks. This article proposes an alternative process to produce shikimic acid feedstock through the bioenhancement of graminoid crops using glyphosate. To demonstrate, a Gulf cultivar of Italian annual ryegrass (Lolium multiflorum Lam.) was grown in controlled greenhouse conditions and Yamhill winter wheat (Triticum aestivum L.) was grown in a field trial. Plants were treated with a range of glyphosate doses and harvested between 48 and 298 h following application. Samples were dried, extracted, and analyzed by high performance liquid chromatography. Shikimic acid levels increased up to four‐fold in glyphosate‐treated Gulf annual ryegrass, a plant with high native shikimic acid. Concentrations of shikimic acid in Yamhill winter wheat, a plant low in native shikimic acid, increased from below method detection limits (<19 mg kg−1) in the control groups to >2000 mg kg−1 in treatment groups harvested after 169 h post application. Estimated biomass accumulation of shikimic acid were projected using concentrations observed in these trials for annual ryegrass, alfalfa (Medicago sativa L.), and winter wheat based on published biomass yields resulted in 21.1 to 299 kg of potential shikimic acid production per hectare, which meet or exceed current feedstocks. This study provides evidence that glyphosate can be used to bioenhance graminoid forage crops to produce elevated shikimic acid levels throughout the entire plant biomass, resulting in a substantially greater yield of shikimic acid than current botanical sources on a per‐hectare basis.

Glyphosate accumulation, translocation, and biological effects in Coffea arabica after single and multiple exposures

Abstract In perennial crops like coffee, glyphosate drift exposure can occur multiple times during its commercial life span. Due to limited glyphosate degradation in higher plants, a potential accumulation of glyphosate could lead to increased biological effects with increased exposure frequency. In this study, we investigated glyphosate translocation over time, and its concentration and biological effects after single and multiple simulated spray-drift exposures. Additionally, shikimic acid/glyphosate ratios were used as biomarkers for glyphosate binding to its target enzyme. Four weeks after the exposure, glyphosate was continuously translocated. Shikimic acid levels were linear correlated with glyphosate levels. After two months, however, glyphosate appeared to have reduced activity. In the greenhouse, multiple applications resulted in higher internal glyphosate concentrations. The time of application, however, was more important regarding biological effects than the number of applications both in the greenhouse and in the field. In the field, berry yield, the most important biological response variable, was reduced 26% by the first out of four sequential applications of glyphosate at 64 g a.e. ha −1 each. The three subsequent applications did not reduce yield any further.

Quick tests for detecting glyphosate-resistant Italian and perennial ryegrass

Three quick tests were evaluated for detecting glyphosate-resistant biotypes of Italian ryegrass and perennial ryegrass. Biotypes of these two species were used that were 13.4 and 7.3 times more resistant to glyphosate, respectively, than susceptible biotypes when assessed using a sprayed pot study. One assay exposed germinating seeds of resistant and susceptible populations for 8 days to different concentrations of glyphosate. Measurements of reduction in seedling root growth gave an estimate of resistance magnitude of 10.8 and 8.9 for Italian ryegrass and perennial ryegrass, respectively, similar to that from the sprayed pot study. Two other assays were tested and were able to differentiate resistant and susceptible biotypes. One measured the relative levels of shikimic acid in leaves following exposure to glyphosate; four to seven times more shikimic acid accumulated in glyphosate-susceptible populations of Italian and perennial ryegrass than in resistant populations. The other assay involved growing tillers of the plants in glyphosate solutions and the results showed that at glyphosate concentrations of 10 and 40 mg/L, the plantlets of resistant plants showed negligible visual injury and growth reduction compared with susceptible ones. Results obtained from these assays were not affected by whether the glyphosate formulation used was an isopropylamine salt or potassium salt.

Zinc Accumulation and Tolerance in Solanum nigrum are Plant Growth Dependent

Zinc tolerance, accumulation, and organic acid production by Solanum nigrum, a known Zn accumulator, was studied during pre- and post-flowering stages of development. The plants, when challenged with Zn concentrations lethal to plantlets, showed an increase in tolerance from pre-flowering to post-flowering, which was accompanied by a reduction of Zn translocation to the aerial plant parts. Treatment with Zn induced a differential response in organic acids according to the plant organ and developmental stage. In the roots, where Zn concentrations were similar in pre- and post-flowering plants, a general decrease in organic acid in pre-flowering roots contrasted with the increase observed in post-flowering plants. In the stems, Zn induced a generalized increase in organic acids at both growth stages while in the leaves, a slight increase in malic and shikimic was observed in pre-flowering plants and only shikimic acid levels were significantly increased in post-flowering plants. This work shows that Zn accumulation and tolerance in S. nigrum vary during plant development – an observation that may be important to improve the efficiency of phytoremediation approaches. Furthermore, the data suggest the involvement of specific organic acids in this response.

Glyphosate Effects on Sugarcane Metabolism and Growth

Glyphosate is the most widely used herbicide in the world. In sugarcane, it is used as a herbicide when applied at its field rate, but it is also used as ripener when applied as low doses. However, the effects of glyphosate on plant metabolism and sugarcane growth are not fully understood. This study aimed to evaluate the metabolic changes and the effects on sugarcane plant growth caused by the application of different doses of glyphosate. Sugarcane plants were grown in a greenhouse and subjected to glyphosate applications at doses of 7.2; 18; 36; 72; 180; 360 and 720 g a.e. ha-1. Plants grown without an herbicide application were used as a control. Plants from each treatment were collected at 2, 7, 14, and 21 days after treatment (DAT) application to quantify the levels of shikimic acid, quinic acid, shikimate-3-phosphate, glyphosate, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), phenylalanine, tyrosine, and tryptophan. Visual evaluations of plant intoxication were performed at the same time as the collection of plants, and the quantification of their shoot dry biomass was performed at 21 DAT. At doses of glyphosate greater than 72 g a.e. ha-1, increases in the levels of shikimic acid, quinic acid, and shikimate-3-phosphate occurred and AMPA was detected in the plants. Initially, glyphosate caused increases in the plant levels of phenylalanine and tyrosine at doses of 72 and 180 g a.e. ha-1, although a decrease in the levels of aromatic amino acids subsequently occurred at and above the doses of 72 or 180 g a.e. ha-1. The doses ranging from 7.2 to 36 g a.e. ha-1 promoted an increase in plant shoot biomass, and doses greater than 72 g a.e. ha-1 caused significant reductions in dry mass.

Quantitative metabolome profiling of Illicium anisatum by capillary electrophoresis time-of-flight mass spectrometry

We used capillary electrophoresis time-of-flight mass spectrometry (CE-TOFMS) to characterize the metabolic profiles of the seed, pulp, stem and leaf of Illicium anisatum. CE-TOFMS detected more than 1000 polar metabolites within 40 min, of which 58 were annotated and quantified. Seed had higher levels of glycolytic metabolites than pulp, stem and leaf, while leaf had higher levels of TCA cycle and nucleoside metabolites. Among amino acid metabolites, levels of Gln, Glu, and Asp were higher in almost every organ. Levels of shikimic acid, the source compound for Tamiflu, were high in all organs, ranging from 6.84% to 28.82%. These results indicate that CETOFMS-based metabolomics offers an efficient, convenient method for comprehensive metabolite profiling, and may be a powerful tool for the screening of drug discovery.

Accumulation of H2O2 in xylem fluids of cucumber stems during ASM-induced systemic acquired resistance (SAR) involves increased LOX activity and transient accumulation of shikimic acid

Systemic acquired resistance (SAR) to Colletotrichum orbiculare was induced in young cucumber (Cucumis sativus) plants within 3 h of ASM (acibenzolar-S-methyl) application onto the first leaves. A potent signal associated with significant accumulation of hydrogen peroxide in xylem fluids from severed stems appeared to be rapidly translocated from elicited lower leaves within 3 h and 6 h after treatment. Some metabolites of the shikimate, phenylpropanoid and lignin biosynthetic pathways were quantified and significant increases in the levels of shikimic acid were observed in ASM-treated plants challenge-inoculated with the anthracnose fungus. Furthermore, the expression of the 5-enolpyruvylshikimate-3-phosphate synthase gene (EPSPS) was 1.5 times higher within 12 h after ASM treatment in challenge-inoculated plants than in the untreated control. The involvement of lipoxygenase activity, shikimic acid and others such as caffeic acid in the induction of SAR is discussed.

Glyphosate applied at low doses can stimulate plant growth

Glyphosate blocks the shikimic acid pathway, inhibiting the production of aromatic amino acids and several secondary compounds derived from these amino acids. Non-target plants can be exposed to low doses of glyphosate by herbicide drift of spray droplets and contact with treated weeds. Previous studies have reported that low doses of glyphosate stimulate growth, although these data are very limited. The objective of this study was to determine the effects of low glyphosate doses on growth of a range of plant species. Growth of maize, conventional soybean, Eucalyptus grandis Hill ex Maiden, Pinus caribea L. and Commelia benghalensis L. was enhanced by 1.8-36 g glyphosate ha(-1). Growth of glyphosate-resistant soybean was unaffected by any glyphosate dose from 1.8 to 720 g AE ha(-1). The optimum doses for growth stimulation were distinct for plant species and tissue evaluated. The greatest stimulation of growth was observed for C. benghalensis and P. caribea. Shikimic acid levels in tissues of glyphosate-treated soybean and maize were measured and found to be elevated at growth-stimulating doses. Subtoxic doses of glyphosate stimulate the growth of a range of plant species, as measured in several plant organs. This hormesis effect is likely to be related to the molecular target of glyphosate, since the effect was not seen in glyphosate-resistant plants, and shikimate levels were enhanced in plants with stimulated growth.

Tissue-culture-responsive and autotetraploidy-responsive changes in metabolic profiles of cucumber (Cucumis sativus L.)

Somaclonal variation commonly occurs during in vitro plant regeneration and may introduce unintended changes in numerous plant characters. In order to assess the range of tissue-culture-responsive changes on the biochemical level, the metabolic profiles of diploid and tetraploid cucumber R1 plants regenerated from leaf-derived callus were determined. Gas chromatography and mass spectrometry were used for monitoring of 48 metabolites and many significant changes were found in metabolic profiles of these plants as compared to a seed-derived control. Most of the changes were common to diploids and tetraploids and were effects of tissue culture. However, tetraploids showed quantitative changes in 14 metabolites, as compared to regenerated diploids. These changes include increases in serine, glucose-6P, fructose-6P, oleic acid and shikimic acid levels. Basing on this study we conclude that the variation in metabolic profiles does not correlate directly with the range of genome changes in tetraploids.

Glyphosate applied preharvest induces shikimic acid accumulation in hard red spring wheat (Triticum aestivum).

Glyphosate is a nonselective herbicide used as a harvest aid in a variety of crops. Glyphosate is absorbed into the foliage and translocated to metabolically active regions in the plant where it interferes with the shikimic acid pathway. Experiments were conducted to determine the accumulation and distribution of shikimic acid in wheat treated with glyphosate at soft and hard dough stages of kernel development and to determine the fate of shikimic acid during milling and bread making. Elevated levels of shikimic acid were detected throughout the wheat plant. Shikimic acid concentrations peaked 3-7 days after treatment and then declined until harvest. Shikimic acid content was 3-fold greater in flour and 2-fold greater in the bread derived from treated wheat than nontreated wheat. Similarly, elevated levels of shikimic acid were found in the crumbs and crust of bread made with flour from glyphosate treated wheat. Glyphosate applied preharvest resulted in shikimic acid accumulation in hard red spring wheat and subsequent end-use products.

Physiological and morphological response of glyphosate-resistant and non-glyphosate-resistant cotton seedlings to root-absorbed glyphosate

The level of tolerance in herbicide-resistant plants may vary among different tissues or growth stages. Studies were conducted to determine relative tissue sensitivity in glyphosate-resistant (GR) and non-GR cotton seedlings to the herbicide glyphosate. Glyphosate is often applied as a pre-plant treatment (burndown) in minimal tillage cotton production systems to remove any unwanted, emerged vegetation. Timing of these glyphosate applications may be in close proximity to the time of planting and seedling emergence. As glyphosate leaches from roots of nearby senescing weeds, it may be absorbed into the roots of cotton seedlings. Therefore, cotton seedlings were grown in hydroponic solutions containing technical grade glyphosate to ensure constant exposure to glyphosate. In all tissues, GR cotton required a greater concentration of glyphosate to reach 50% fresh weight reduction than non-GR cotton. Glyphosate inhibited the growth of non-GR cotton cotyledons, hypocotyls, and roots 50% at concentrations of 23, 69, and 27 μM glyphosate, respectively. In contrast, growth of GR cotton cotyledons, hypocotyls, and roots was inhibited by 50% at 3.5-, 8-, and 5-fold greater glyphosate concentrations, respectively, than non-GR cotton tissues. Correspondingly, shikimic acid, an intermediate in the shikimic acid pathway, which accumulates upon 5-enolpyruvyl 3-shikimate phosphate synthase (EPSP synthase) inhibition, reached levels of 17.3, 21.6, and 8.8 μM g −1 fresh weight at 1 mM glyphosate in non-GR cotyledons, hypocotyls, and roots, respectively. In contrast, shikimic acid levels in GR cotton were 4.2, 14.0, and 8.2 μM g −1 fresh weight at 1 mM glyphosate for cotyledons, hypocotyls, and roots, respectively. Thus, roots of GR and non-GR cotton accumulate similar amounts of shikimic acid, whereas GR cotyledons and hypocotyls accumulated less shikimic acid than the corresponding non-GR tissues in response to glyphosate treatments. Additionally, glyphosate inhibited the development of lateral roots at concentrations of 0.01 or 0.1 μM glyphosate greater, in GR and non-GR cotton, respectively. Lateral roots of GR and non-GR cotton inhibited by glyphosate appeared shorter and were surrounded by a thick layer of necrotic cells or root exudate which was not present in roots from plants grown in media not containing glyphosate. The quantity of GR CP4-EPSP synthase was 4.7 and 6.6 times greater in cotyledons than in hypocotyls and roots, respectively. Tissues from dark-grown GR cotton seedlings contained 1.2–2.1 times less CP4-EPSP synthase than their light-grown counterparts. Because lateral root development was inhibited, fresh weight was reduced, and shikimic acid accumulated following treatment with glyphosate in both GR and non-GR cotton, the potential exists for glyphosate to negatively affect cotton seedling establishment.

Influence de la fourniture en assimilats sur la maturation et la qualité de la pêche (Prunus persica L. 'Suncrest')

Maturity and sensory evaluation of peach (cv. Suncrest) fruits were evaluated in response to three leaf:fruit ratios, 6, 18 and 30, respectively. Fruit growth rates increased with increasing leaf:fruit ratios so that, at maturity, fruit weights of 75, 140 and 180 g were obtained from the three treatments, respectively. Metabolic activity (oxygen consumption) although indifferent between treatments when fruits were immature, segregated according to leaf:fruit ratios as fruits matured. Autocatalytic production of ethylene was delayed in fruits suffering from nutritional stress and the intensity of ethylene production was also dependent on assimilate supply. Sugars, especially sucrose, accumulated at slower rates when assimilate supply was lowest, i.e. six leaves per fruit. Malic and citric acids metabolisms were influenced by the leaves:fruit ratios. Quinic and shikimic acid levels were reduced according to the treatments. Key words: Peach, ripening, quality, assimilates, metabolic activity, sugars, acids