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At least 19 recordsLinked to original sources

Identification and gene expression of anaerobically induced enolase in Echinochloa phyllopogon and Echinochloa crus-pavonis.

Enolase (2-phospho-D-glycerate hydrolase, EC 4.2.1.11) has been identified as an anaerobic stress protein in Echinochloa oryzoides based on the homology of its internal amino acid sequence with those of enolases from other organisms, by immunological reactivity, and induction of catalytic activity during anaerobic stress. Enolase activity was induced 5-fold in anoxically treated seedlings of three flood-tolerant species (E. oryzoides, Echinochloa phyllopogon, and rice [Oryza sativa L.]) but not in the flood-intolerant species (Echinochloa crus-pavonis). A 540-bp fragment of the enolase gene was amplified by polymerase chain reaction from cDNAs of E. phyllopogon and maize (Zea mays L.) and used to estimate the number of enolase genes and to study the expression of enolase transcripts in E. phyllopogon, E. crus-pavonis, and maize. Southern blot analysis indicated that only one enolase gene is present in either E. phyllopogon or E. crus-pavonis. Three patterns of enolase gene expression were observed in the three species studied. In E. phyllopogon, enolase induction at both the mRNA and enzyme activity levels was sustained at all times with a further induction after 48 h of anoxia. In contrast, enolase was induced in hypoxically treated maize root tips only at the mRNA level. In E. crus-pavonis, enolase mRNA and enzyme activity were induced during hypoxia, but activity was only transiently elevated. These results suggest that enolase expression in maize and E. crus-pavonis during anoxia are similarly regulated at the transcriptional level but differ in posttranslational regulation, whereas enolase is fully induced in E. phyllopogon during anaerobiosis.

Amino Acid Sequence↗

Changes in hexokinase activity in echinochloa phyllopogon and echinochloa crus-pavonis in response to abiotic stress

Hexokinase (HXK; EC 2.7.1.1) regulates carbohydrate entry into glycolysis and is known to be a sensor for sugar-responsive gene expression. The effect of abiotic stresses on HXK activity was determined in seedlings of the flood-tolerant plant Echinochloa phyllopogon (Stev.) Koss and the flood-intolerant plant Echinochloa crus-pavonis (H.B.K.) Schult grown aerobically for 5 d before being subjected to anaerobic, chilling, heat, or salt stress. HXK activity was stimulated in shoots of E. phyllopogon only by anaerobic stress. HXK activity was only transiently elevated in E. crus-pavonis shoots during anaerobiosis. In roots of both species, anoxia and chilling stimulated HXK activity. Thus, HXK is not a general stress protein but is specifically induced by anoxia and chilling in E. phyllopogon and E. crus-pavonis. In both species HXK exhibited an optimum pH between 8.5 and 9.0, but the range was extended to pH 7.0 in air-grown E. phyllopogon to 6.5 in N2-grown E. phyllopogon. At physiologically relevant pHs (6.8 and 7.3, N2 and O2 conditions, respectively), N2-grown seedlings retained greater HXK activity at the lower pH. The pH response suggests that in N2-grown seedlings HXK can function in a more acidic environment and that a specific isozyme may be important for regulating glycolytic activity during anaerobic metabolism in E. phyllopogon.

Journal Article↗

Germination of Echinochloa crus-galli (Barnyard Grass) Seeds under Anaerobic Conditions : Respiration and Response to Metabolic Inhibitors.

Echinochloa crus-galli L. Beauv., a rice-field weed, can germinate and grow for extended periods of time in an anaerobic environment. Compared to pea, which does not germinate under anaerobiosis, the evolution of CO(2) in Echinochloa and rice is lower and the peak rate of CO(2) evolution is delayed when germinated without oxygen. The plants studied also differ with respect to their respiration ratio ([CO(2)] N(2)/[CO(2)] air) and metabolism used during the early stages of germination. Echinochloa does not increase its glycolytic rate under anaerobiosis, whereas pentose phosphate pathway activity appears to increase during the first 40 to 50 hours of germination.Based on its response to metabolic inhibitors (NaF, dinitrophenol, and malonate), anaerobic metabolism in Echinochloa proceeds primarily through glycolysis, with partial operation of the tricarboxylic acid cycle and little or no oxidative phosphorylation. Also, Echinochloa is sensitive to CN during aerobic germination, whereas rice appears to be able to shift to CN-insensitive electron transport. Finally, the effectiveness of cyanide and azide on inhibiting germination of Echinochloa in N(2), but not CO, suggests that cytochrome oxidase is not used to reoxidize pyridine nucleotides in the absence of oxygen. The possible existence of an alternate electron acceptor is discussed.

Journal Article↗

Botanical identification of several Echinochloa biotypes collected in Spanish rice fields with control failures of cyhalofop-butyl.

There is some disagreement about the species that constitute Echinochloa. Correct identification is agronomically and economically important because Echinochloa spp. are aggressive invaders and difficult to control. The identification of Echinochloa spp. is complicated because of the morphological diversity shown by the genus. This work was initiated because of the differential response to cyhalofop-butyl treatment shown by some populations of Echinochloa spp. Four biotypes were selected for botanical identification: two biotypes collected in the Seville area, one of them susceptible to cyhalofop-butyl (ED50 = 64 g a.i.ha(-1)) and the other one tolerant (ED50 = 560 g a.i.ha(-1)), one tolerant biotype collected in the Badajoz area (ED50 = 420 g a.i.ha(-1)) and one tolerant biotype collected in the Valencia area (ED50 = 860 g a.i.ha(-1)). Botanical identification was carried out following Carretero's Keys (1981) on plants grown at the site of origin. The main distinguishable character of the species was the length of the upper glume. The following results were obtained: the susceptible biotype collected in the Seville area and the tolerant biotype collected in the Valencia area were characterized as Echinochloa oryzoides, the tolerant biotype collected in Badajoz was characterized as E. oryzicola and the tolerant biotype collected in Seville area as E. hispidula.

Drug Tolerance↗

Morphological and molecular characterization of different Echinochloa spp. and Oryza sativa populations.

Echinochloa P. Beauv. is an important genus because many of its species are weeds infesting most paddy fields, which can reduce the rice grain production by up to 80%. A controversy exists about the taxonomy of the genus due to the high level of morphological variations found in these species. Cyhalofop-butyl, an aryloxyphenoxy-propionate herbicide, is used to control Echinochloa spp. in paddy fields, although differences in susceptibility were found between different Echinochloa species. E. colona was highly susceptible [ED50= 34 g of active ingredient (ai) ha(-1)]; very similar results were obtained with the remaining species. By contrast, E. oryzicola (170 g of ai ha(-1)) was less sensitive, with the herbicide symptoms appearing later. Because of this differential susceptibility, morphological and molecular studies were carried out. A morphological study, using 21 characters both quantitative and qualitative of spikelets and seedlings, was capable of clearly distinguishing closely related E. crus-galli plants (two populations), E. muricata and E. crus-pavonis, and E. oryzicola, E. utilis, and E. colona species. The resolution of Echinochloa species at the molecular level, based on RAPD analyses, was fairly consistent with morphological analysis results. Among the 60 primers screened, 21 primers exhibited polymorphic bands and produced a total of 136 RAPD markers. Of all the amplified fragments, 90 were found to be polymorphic. E. oryzicola and E. colona were clearly separated, and the RAPD analyses showed that both E. crus-galli populations were 100% related and 51% related to E. utilis, whereas E. crus-pavonis and E. muricata (73% similarity) appeared as being clearly separated from this group.

DNA, Plant↗

Constitutive and Inducible Aerobic and Anaerobic Stress Proteins in the Echinochloa Complex and Rice.

Anaerobic stress resulted in a change in the protein accumulation patterns in shoots of several Echinochloa (barnyard grass) species and Oryza sativa (L.) (rice) as resolved by two-dimensional gel electrophoresis. Of the six Echinochloa species investigated, E. phyllopogon (Stev.) Koss, E. muricata (Beauv.) Fern, E. oryzoides (Ard.) Fritsch Clayton, and E. crus-galli (L.) Beauv. are tolerant of anaerobiosis and germinate in the absence of oxygen, as does rice. In contrast, E. crus-pavonis (H.B.K.) Schult and E. colonum (L.) Link are intolerant and do not germinate without oxygen. Computer analysis of the protein patterns from the four tolerant species and rice indicated that the anaerobic response is of five classes: class 1 proteins, enhanced under anaerobiosis (9 to 13 polypeptides ranging from 16-68 kD); class 2 proteins, unique to anaerobiosis (1 to 5 polypeptides ranging from 17-69 kD); class 3 proteins, remained constant under aerobiosis and anaerobiosis; class 4 proteins, prominent only in air and repressed under anoxia (3 to 7 polypeptides ranging from 19-45 kD); and class 5 proteins, unique to aerobiosis (1 to 4 polypeptides ranging from 18-63 kD). In the intolerant species, E. colonum and E. crus-pavonis, no polypeptides were enhanced or repressed under anoxia (class 1 and class 4, respectively), whereas in the tolerant Echinochloa species and rice, a total of at least 9 to 13 anaerobic stress proteins and 4 to 7 "aerobic" proteins were noted. Immunoblotting identified two of the major anaerobic stress proteins as fructose-1,6-bisphosphate aldolase and pyruvate decarboxylase. Based on the differential response of the intolerant species to anaerobiosis, we suggest that another set of genes, whose products may not necessarily be among the major anaerobic stress polypeptides, might confer tolerance in Echinochloa under prolonged anaerobic stress.

Journal Article↗

[Leaf photosynthetic acclimation of Echinochloa crusgalli grown in rice field to free-air CO2 enrichment (FACE)].

A comparative study was made between the leaves of Echinochloa crusgalli grown at 580 (FACE) and 380 (control, ambient air) mumol CO2 mol-1 air by observation of net photosynthetic rates (Pn) and the contents of soluble protein and the key enzyme of photosynthetic carbon assimilation, Rubisco. When measured at the ambient air CO2 concentration (380 mumol.mol-1), Pn were significantly lower in leaves grown under FACE conditions than that in those leaves grown in the ambient air. This indicates that photosynthetic acclimation to high CO2 occurs in the leaves grown under FACE conditions. Also, the stomatal conductance (Gs) and intercellular CO2 concentration (Ci) were decreased significantly in the leaves grown under FACE. The content of total soluble protein was much lower in the leaves grown under FACE conditions than that the in the control, and the content of Rubisco was also decreased in the FACE leaves, but the difference was not significant. From these results it is deduced that the photosynthetic acclimation to high CO2 in Echinochloa crusgalli leaves grown under FACE conditions is mainly related to the partial closure of stomata and the decrease in soluble protein containing some enzymes.

Acclimatization↗

Is it possible to detect Echinochloa spp. tolerance to ACCase-inhibiting herbicides using a simple quick tolerance test?

The objective of this work was to evaluate the reliability of one quick tolerance test that would enable us, in only six days, to quantify tolerance levels of one biotype to one or more herbicides. For this purpose, we evaluated tolerance levels to cyhalofop-butyl of five Echinochloa spp. biotypes: muricata, crus-galli, crus-pavonis, oryzicola and utilis, with unknown records of herbicide treatment. Moreover, two biotypes of Echinochloa phyllopogon were tested, one of them resistant (R) to fenoxaprop-P-ethyl and the other one susceptible (S). The Oryza sativa Puntal var. and Oryza sativa var. (wild rice) were also checked in order to demonstrate cyhalofop-butyl selectivity profiles. The assays were conducted with petri-dishes where, over the following increasing doses, fifty seeds per biotype and dose, were placed in each one: 0, 3, 6, 12, 18, 24, 48 and 60 ppm of cyhalofop-butyl and codacide oil adjuvant. Six days later, the following parameters were evaluated: plumule length, root length, germination (%) and fresh weight reduction (%). E. muricata germination was reduced by 50% with a 6 ppm dose. A non linear relation dose-germination was observed in the rest of the biotypes. The plumule length permitted the ranking of the biotypes into three groups: (1) resistant (E. phyllopogon R) or very tolerant (Oryza sativa Puntal var. and wild rice), those with a reduction of less than 30%, (2) tolerant, between 30 and 60% (E. oryzicola), and (3) susceptible, with a reduction of over 80% (E. muricata, E. crus-galli, E. crus-pavonis, E. utilis and E. phyllopogon S). Only Oryzo sativa and E. phyllopogon R had a minimal reduction of fresh weight (less than 15%). The assays were repeated with whole plants and we checked the accuracy of this test that indicated the resistance level of one biotype in a quick, reliable and economic way.

Drug Tolerance↗

Alternative control of two biotypes of Echinochloa phyllopogon susceptible and resistant to fenoxaprop-ethyl.

Rice (Oryza sativa var.), is one of the most important crops worldwide, and is cultivated in the five continents since it adapts itself to all climatic conditions. The most important weeds that reduce the world rice yield are Echinochloa spp., annual gramineae, which, because of the selection pressure imposed on them, have developed resistance to a large series of herbicides. Two Echinochloa phyllopogon biotypes were studied, one of them resistant to molinate, thiobencarb and fenoxaprop-ethyl and the other one susceptible to these herbicides, both originating from California rice fields. In these biotypes, the effects of other herbicides were evaluated, some of them with the same mode of action [profoxydim (Aura) and cyhalofopbutyl (Clincher), both ACCase inhibitors] and others with different modes of action [quinclorac (Facet) belonging to auxinic herbicide families; bispyribac-Na (Nominee) and azimsulfuron (Gulliver), both ALS inhibitors]. The only herbicide that effectively controlled the R biotype was profoxydim (95% control). Cyhalofop-butyl, quinclorac and bispyribac-Na did not control the R biotype by more than 40%. There is no doubt that azimsulfuron hardly had any effect (14%). On the other hand, in the S biotype, three herbicides were quite effective: profoxydim (93%), quinclorac (93%), and cyhalofop-butyl (90%). Bispyribac-Na and azimsulfuron hardly had any effect on the S biotype, with no significant differences in either herbicide (20%).

Echinochloa↗

[Inhibitory effects of allelopathic rice materials on Echinochloa crus-galli and related field weeds].

By using the modified relay seeding technique, more than 10 allelopathic rice materials were obtained from 500 rice germplasm, and their allelopathic inhibitory effects on weeds were evaluated under field condition. The results showed that under direct-seeded condition, the allelopathic rice materials Gumei 2, Xiayitiao, Jizaoxian, Ganzaoxian and Shangnuo 1 had more obvious inhibitory effects on Echinochloa crus-galli than non-allelopathic rice materials Xiushui 63 and Chunjiang 11, while the allelopathic rice material Milyang 54 had the best inhibitory effect on field weeds. Under field-transplanting condition, the allelopathic rice materials Gumei 2, Qingkun 1, Xiayitiao and Jizaoxian had significant inhibitory effects on Echinochloa crus-galli over non-allelopathic materials Xiushui 63 and Chunjiang 11. There existed significant differences in some agronomic characters among rice materials. Allelopathic rice materials Xiayitiao and Jizaoxian had higher plant height and stronger tillering activity, but had smaller leaf areas of the 3 upper leaves.

Biomass↗

[Prevention efficiency of Exserohilum monoceras with chemical herbicides against Echinochloa crus-galli in paddy field].

This paper studied the impact of several herbicides on the conidium germination of Exserohilum monoceras strain X27 in petri dish, and the synergistic effects of the pathogen and chemical herbicide quinclorac or propanil against Echinochloa crus-galli in greenhouse. The prevention efficiency of the tank-mixture of pathogen and quinclorac was also evaluated in paddy field. The results showed that test herbicides except quinclorac and bensulfulfuronmethyl could inhibit conidium germination and hypha growth to different degree. A significant synergism was observed between the pathogen and quinclorac. Adding quinclorac could obviously increase the prevention efficiency against Echinochloa crus-galli. Under field condition, the single use of pathogen could only control about 60% of the weed, while the efficiency of pathogen-quinclorac mixture could reach 90%.

Echinochloa↗

[Biodegradation of acetochlor in soil and its persistence against Echinochloa crusgalli].

Gas chromatograph and bioassay were used to study biodegradation of acetochlor and its influence on the persistence against Echinochloa crusgalli in soil. The results showed that half-life of degradation of acetochlor was significantly shorter in unsterilized soil than that in sterilized soil under the same experimental conditions of concentrations, water content and temperature, when acetochlor was added to the soil with concentrations of 1.25, 2.5 and 5.0 mg x kg(-1) respectively, which demonstrated that microorganisms could evidently degrade acetochlor in soil. The experiment on degradation of three main kinds of microorganism cultivated in liquid culture medium gave same results above. The bioassay' s result showed that the period of acetochlor persistence against Echinochloa crusgalli was shorter in unsterilized soil than that in sterilized soil, which indicated that existence of microorganism could accelerate the degradation of acetochlor and shorten remaining time of the herbicide in soil, consequently reduce its persistence against the weed.

Biodegradation, Environmental↗

Protein, calcium, and iron content of wild and cultivated species of Echinochloa.

Two species of Echinochloa millets and their direct wild ancestor species were analyzed for proximate composition, and amino acid, calcium, and iron content. Additionally, lactate polyacrylamide gel electrophoresis (PAGE) was performed to separate and resolve prolamin polypeptide present in the wild and domesticated species. The protein, calcium, and iron content of the four species were comparable to or greater than in other major cereals. Calcium was higher in each of the wild species than their domesticated counterpart. Essential amino acid values for the three species analyzed were generally higher than the FAO/WHO standards, except for lysine. Densitometric analysis of lactate PAGE gels revealed that the domesticated species contained prolamin, polypeptides that were either absent or present in smaller amounts in the wild species. The results indicate a wide variation in the content of examined nutrients and suggest that there is opportunity for improvement in the nutritional value of the Echinochloa millets via selective crossbreeding of wild and domesticated species.

Amino Acids↗

Effects of chromium and nickel on germination and growth in tolerant and non-tolerant populations of Echinochloa colona (L.) Link.

The tolerance of populations of a grass, Echinochloa colona, growing abundantly on chromite minewaste dumps, was tested in two separate experiments. Seed-based experiments indicate that the populations growing naturally on uncontaminated sites, germinated better in nutrient solutions without metal than those collected from minewaste dumps. Metal tolerance indices were greater in the plant populations derived from metal contaminated sites and better growth of these plants was noted on mine spoil soil-mix in the ratio of 1:1; the percentage of seed germination and the rate of seedling growth, however, declined in a soil compost containing 25% mine spoil and 75% uncontaminated (control) soil. Populations of Echinochloa colona occurring naturally on chromite mine spoils, therefore, appear to have developed metal tolerance. It is maintained by a balanced and stable genetic system built up and adjusted by natural selection. Such material is very suitable to be used in restoration work designed to produce an effective vegetation cover to improve the derelict land and to reduce erosion. This finding might be useful in revegetation programmes on metalliferous minewastes.

Chromium↗

Effect of Aerobic Priming on the Response of Echinochloa crus-pavonis to Anaerobic Stress (Protein Synthesis and Phosphorylation).

Echinochloa species differ in their ability to germinate and grow in the absence of oxygen. Seeds of Echinochloa crus-pavonis (H.B.K.) Schult do not germinate under anoxia but remain viable for extended periods (at least 30 d) when incubated in an anaerobic environment. E. crus-pavonis can be induced to germinate and grow in an anaerobic environment if the seeds are first subjected to a short (1-18 h) exposure to aerobic conditions (aerobic priming). Changes in polypeptide patterns (constitutive and de novo synthesized) and protein phosphorylation induced by aerobic priming were investigated. In the absence of aerobic priming protein degradation was not evident under anaerobic conditions, although synthesis of a 20-kD polypeptide was induced. During aerobic priming, however, synthesis of 37- and 55-kD polypeptides was induced and persisted upon return of the seeds to anoxia. Furthermore, phosphorylation of two 18-kD polypeptides was observed only in those seeds that were labeled with 32PO4 during the aerobic priming period. Subsequent chasing in an anaerobic environment resulted in a decrease in phosphorylation of these polypeptides. Likewise, phosphorylation of the 18-kD polypeptides was not observed if the seeds were labeled in an anaerobic atmosphere. These results suggest that the regulated induction of the 20-, 37-, and 55- kD polypeptides may be important for anaerobic germination and growth of E. crus-pavonis and that the specific phosphorylation of the 18-kD polypeptides may be a factor in regulating this induction.

Journal Article↗

Anaerobiosis in Echinochloa crus-galli (Barnyard Grass) Seedlings : Intermediary Metabolism and Ethanol Tolerance.

Tolerance to ethanol and the ability to metabolize key intermediary substrates under anaerobiosis were studied in Echinochloa crus-galli (L.) Beauv. var oryzicola seeds to further characterize the mechanisms which enable it to germinate and grow without O(2).Our results indicate that E. crus-galli var oryzicola possesses an inherently high tolerance to ethanol and is able to metabolize low levels of ethanol in the absence of O(2). Concentrations of ethanol 45-fold greater than endogenous levels did not prove toxic to germinating seeds.Five-day anaerobically grown seedlings of E. crus-galli var oryzicola metabolized added [(14)C]sucrose primarily to CO(2) and ethanol. Of the soluble compounds labeled, the phosphorylated intermediates of glycolysis and the oxidative pentose phosphate pathway predominated more under anaerobiosis than in air. In addition, organic acids and lipids were labeled from [(14)C]sucrose, the latter indicating that metabolism of carbohydrate via acetyl-CoA occurred in the absence of O(2). Lipids were also labeled when seeds were supplied with [(14)C]ethanol or [(14)C]acetate. Labeling experiments using the above compounds plus [(14)C]NaHCO(3), showed further labeling of organic acids; succinate and citrate being labeled under nitrogen, while fumarate was formed in air.The above metabolic characteristics would allow for the maintenance of an active alcoholic fermentation system which, along with high alcohol dehydrogenase activity, would continue to recycle NAD and result in continued energy production without O(2). In addition, Echinochloa's ability to metabolize carbohydrate intermediates and to synthesize lipids indicates that mechanisms exist for providing the carbon intermediates for biosynthesis, particularly membrane synthesis for growth, even in the absence of O(2).

Journal Article↗

The potential efficiency of irrigation management and propargyl bromide in controlling three soil pests: Tylenchulus semipenetrans, Fusarium oxysporum and Echinochloa crus-galli.

Propargyl bromide (3-bromopropyne, 3BP) is a potential alternative for methyl bromide. Little information is available about its efficiency in controlling pests. The purpose of this paper is to estimate the 3BP dose required for killing three pests and to compare the efficiency of water management approaches to that of fumigation. The pests, Fusarium oxysporum Schlecht (fungus), Echinochloa crus-galli (L) Beauv (grass) and Tylenchulus semipenetrans Cobb (nematode) were exposed to different 3BP concentrations in a sandy loam at 30 degrees C in a closed system. The lethal dose for killing 90% of the population (LD90) was calculated from the total applied mass, and varied from 0.3 microg g(-1) soil for the nematode, 3 microg g(-1) for the grass, and 9 microg g(-1) for the fungus. The concentration-time index for killing 90% of the population (CT90) was 11 microg g(-1) h for the nematode, 112 microg g(-1) h for the grass and 345 microg g(-1) h for the fungus. 3BP seems as efficient as other fumigant alternatives in controlling these pests. Using an open system, it was shown that the volume of soil in which the pests were controlled varied for different irrigation managements. Even 96 h after fumigation (with a concentration 10 times higher than would potentially be applied in the field), more than 20% of the soil volume had not reached the fungus and grass CT90 of the non-irrigated soil. The soil underneath the furrow and the bed reached CT90 only slowly in all irrigated treatments even though techniques for increasing efficiency were used (tarping, surface sealing with water and high application rate).

Agriculture↗

Synthesis and herbicidal activity of new oxazinone herbicides with a long-lasting herbicidal activity against Echinochloa oryzicola.

Chemical modification of the herbicide 1-[2-(benzothiazol-2-yl)isopropyl]-4-methyl-3-phenyl-5H-pyrrolin-2-one (MI-2826) has revealed a new oxazinone herbicide, 3-[2-(7-chlorobenzothiazol-2-yl)isopropyl]-2,3-dihydro-6-methyl-5-phenyl-4H-1,3-oxazin-4-one (MI-3069), for use in paddy fields. In comparing the phyototoxicity of the two herbicides to transplanted rice, the latter was superior to the former and kept the same predominant characteristic to control Echinochloa oryzicola Vasin for a long period of time owing to its long-lasting residual effect.

Drug Residues↗