小麦根质膜H+-ATPase水解活性与吸钾关系研究

以不同基因型小麦根为材料,采用蔗糖不连续密度梯度法制备质膜微囊,研究了钾对质膜H -ATPase水解活性的影响。研究表明:生长环境中钾胁迫会导致小麦根质膜H -ATP酶水解活性增加,且水解活性受钾刺激也增加;生长环境中钾充足会导致此酶水解活性比钾亏缺时低,且水解活性受钾刺激而下降。表明环境钾水平可影响根内H -ATP酶活性及其某些性状。植株K吸收量与根质膜H -ATP酶水解活性及受钾刺激特性关系不明显。决定钾吸收量的因素很多。     

The uptake of [14C] dieldrin via the roots of young cotton plants

The stems and leaves of young cotton plants growing in nutrient solution containing a radioactive dieldrin suspension became radioactive. After 2 weeks, dieldrin was taken up at a constant rate which differered slightly in different environments probably because the plants transpired at different rates.     

Surfactants and the uptake and movement of paraquat in plants

Surfactants are still considered to be agents which either increase spray coverage of leaves with herbicidal solutions and/or increase herbicide penetration into the leaves. Experiments where the method of application largely eliminates leaf wetting as a factor in paraquat uptake show that this is an over-simplification. Its efficiency in the plant is influenced by penetration and most of all by the degree of movement down the plant into untreated leaves. Results on the uptake, movement and biological activity of paraquat are reported using cocksfoot and wheat. A relation is found between paraquat movement and the hydrophilic nature of the surfactant. It moves most when the number of ethylene oxide residues is less than six and it is minimal when the number is 10 to 15. Leaf penetration, however, is at a maximum when movement under the influence of surfactant is least. Partition studies in which surfactants are distributed between leaf wax and water are described. There is a direct correlation between the degree of partition of the surfactant into the wax and the degree of movement of paraquat in cocksfoot and wheat. Surfactants are essential components of a paraquat formulation to wet the leaf surface and increase penetration but, when the surfactant also penetrates into the leaf, it reduces the mobility of paraquat and hence its efficiency.     

Modelling uptake into roots and subsequent translocation of neutral and ionisable organic compounds

A study on uptake of neutral and dissociating organic compounds from soil solution into roots, and their subsequent translocation, was undertaken using model simulations. The model approach combines the processes of lipophilic sorption, electrochemical interactions, ion trap, advection in xylem and dilution by growth. It needs as input data, apart from plant properties, log K_OW, pK_a and the valency number of the compound, and pH and chemical concentration in the soil solution. Equilibrium and dynamic (steady‐state) models were tested against measured data from several authors, including non‐electrolytes as well as weakly acidic and weakly basic compounds. Deviations from the measured values led to further development of the model approach: sorption in the central cylinder may explain the small transpiration stream concentration factor of lipophilic compounds. For non‐electrolytes, the model predicted uptake and translocation with high accuracy. For acids and bases, the tendency of the results was satisfactory. The dynamic model and the equilibrium approach gave similar results for the root concentration factor. The calculation of the transpiration stream concentration factor was more accurate with the dynamic model, but still gave deviations up to factor of ten or more. The dominating process for monovalent weak electrolytes was found to be the ion trap effect. © 2000 Society of Chemical Industry     

Physico-chemical factors affecting uptake by roots and translocation to shoots of weak acids in barley

The uptake from solution of maleic hydrazide, flamprop and a series of phenoxyacetic acids by roots, and their subsequent translocation to shoots, was measured in barley. Both uptake and translocation increased as the pH of the solution decreased, the magnitude of the change varying amongst the chemicals tested. Uptake by roots could be accounted for by the ion-trap mechanism, which assumes that entry of the chemicals occurs largely by passive diffusion of the undissociated form of the acids, with passage of the anions across the cell membranes being very slow. The ratio of the permeability of the cell membranes to the undissociated and dissociated forms of the acids was estimated from the accumulation in roots, and in the phenoxyacetic acid series this ratio was maximal (4×10⁵) for compounds of intermediate lipophilicity. Maleic hydrazide and flamprop had much lower ratios, 1.8×10² and 10³ respectively; the value for flamprop was much less than for phenoxyacetic acids of similar lipophilicity, such as 2, 4- dichlorophenoxyacetic acid, indicating that lipophilicity may not be the sole factor determining the behaviour of weak acids in plants. Translocation to shoots was approximately proportional to the chemical concentrations in the roots.     

Leaching of aldicarb and thiofanox,and their uptake in soils by sugarbeet plants

The leaching of aldicarb and thiofanox in soils (sandy loam, silt loam and sandy clay loam), and their uptake by sugarbeet plants were studied. Three irrigation levels were maintained: half, normal and double dose. The residues were determined as the sum of the insecticidal metabolites (parent compound + sulphoxide+ sulphone) for both pesticides. Leaching was greatly influenced by the amount of water added and the soil type. Under normal conditions, leaching seemed to proceed very slowly, keeping the chemicals available for uptake by the root systems for a long time. The concentration of insecticide in the leaves was highest in beets grown on sandy loam and lowest in those grown on sandy clay loam. The quantity of irrigation did not influence the residue concentration in the leaves greatly, although its influence was obvious on the total residue present (μg per plant). Increasing the water dose always resulted in a higher total residue, and a greater plant weight. The breakdown in the soils was directly related to the water dose. The experiments show that thiofanox was more stable than aldicarb and was taken up by sugarbeet to a greater extent.     

Antidote action of humic substances on atrazine inhibition of sulfate uptake in barley roots

Atrazine 10^?4M rapidly inhibits sulfate uptake by excised barley roots. When humic substances are present in the uptake solution the inhibition is reduced. This effect is enhanced by 10 to 16 hr incubation of the roots in the presence of humus. Humus action is accompanied by the stimulation of leucine incorporation into protein, which, on the contrary, is unaffected by atrazine. The same experiments carried out with barley seedlings, in nutrient solution containing either atrazine or humus, or both, confirm the inhibitory action of atrazine on SO₄^2? absorption by the whole plant and the inhibition reduction by humic substances.     

Studies on the site of uptake by plants of chlortoluron and terbutryne

Experiments were done to observe the pattern of early root development of radish (Raphanus raphatnistrum L.) and perennial ryegrass (Lolium perenne L.), the mobility of chlortoluron following application to the soil surface, the effect of protecting the subterranean shoots of four plant species on their response to chlortoluron and terbutryne and the relative quantities of ¹⁴C-labelled chlortoluron taken up by radish and Avenu fatua from root and shoot zone exposure. Both chlortoluron and terbutryne appear to be able to enter the plants examined, Alopecurus myosuroides, Stellaria media, perennial ryegrass and radish, through roots and shoots. It is suggested that shoot uptake is relatively more important for plants like perennial ryegrass than for those whose roots develop more quickly and invade the soil above the seed, such as radish. The quantities of radioactive chlortoluron taken up from soil containing 400 ng g^?1 showed that less than 3 ng per plant could reduce A. fatua fresh weight by 17–40% while over 30 ng per plans had little effect on radish. By comparison 2 kg ha^?1 chlortoluron applied to the soil surface of pots which were sub-irrigated for 3 weeks gave a concentration of 170 ng g^?1 in the layer of soil 10–12 mm from the surface. It is suggested that for shallow germinating species with herbicides of physical and phytotoxic properties similar to chlortoluron, the solvent action of rainfall, together with diffusion, is enough to allow the transport of toxic quantities to the target plant although any leaching action is likely to increase activity.     

Physicochemical factors affecting the uptake by roots and translocation to shoots of amine bases in barley

The uptake by barley roots from nutrient solution and subsequent transport to shoots of two series of amine bases were measured over 6 to 72 h. The compounds were chosen to span systematically ranges of lipophilicity (assessed using 1-octanol/water partition coefficients, K_ow) and pKa that would include commercial pesticide amines. In a series of six substituted phenethyl amines, strong bases with pKa∽9·5, all the compounds were strongly taken up by roots from solutions of pH 8·0; uptake declined substantially as the pH was lowered to 5·0, especially for the compounds of intermediate lipophilicity (log K_ow 2 to 3). This uptake could be ascribed to three processes: (i) accumulation of the cation inside the root cells due to the negative charge on the plasmalemma, as given by the Nernst equation and important only for the polar compounds which have low permeation rates through membranes; (ii) accumulation into the vacuole by ion-trapping, which was the dominant process at high pH for all compounds and at all pH values for the compounds of intermediate lipophilicity; (iii) partitioning on to the root solids, substantial only for the most lipophilic compounds. Translocation to shoots was proportional to uptake by roots, this ratio being independent of external pH for each compound and being optimal for the compounds of intermediate lipophilicity. Such proportionality was also observed in a series of three weaker bases of intermediate lipophilicity, in which compounds of pKa 7·4 to 8·0 were also well taken up and translocated whereas the very weak base 4-ethylaniline (pKa 5·03) was much less so. Tests with quaternised pyridines confirmed that organic cations move only slowly through membranes. The observed behaviour of the amines could be modelled reasonably well assuming that transport within the plant was dominated by movement across membranes of the non-ionised species, and this appeared to be true even for the most lipophilic phenethylamine (log K_ow 4·67) studied, though its long-distance movement would be as the protonated species. © 1998 Society of Chemical Industry     

农药在植物中的内吸和传导行为与施药技术研究进展

农药的施用方式和施用效果与其在植物中的内吸和传导行为密切相关.农药在植物表面和内部的内吸和传导行为,不仅与其自身理化性质有关,还受植物种类、生长期、生长条件及施药方式等因素的影响.研究农药在植物体内的内吸和传导行为及其影响因素,对于选择合适的施药技术及提高农药利用率具有重要的指导意义.本文综述了农药在植物体内的内吸和传...     

Quinclorac does not inhibit cellulose (cell wall) biosynthesis in sensitive barnyard grass and maize roots

The effect of the auxin herbicide quinclorac on cellulose, callose, and (1→3),(1→4)β-glucan deposition in newly produced cell walls of meristematic root tip cells was examined in maize and barnyard grass. Particularly, the developing cell plate of dividing cells was investigated as a site of de novo cellulose biosynthesis. A cellulose-binding domain of a bacterial cellulase and monoclonal antibodies against the hemicellulose constituents were used for specific labelling in fluorescence microscopic examination. Root-treatment of plants with 100 μM quinclorac in maize and 10 μM quinclorac in barnyard grass decreased cell division activity in root tips and root elongation. Quinclorac did not induce the swelling of root tips into a club shape and a glassy appearance of tissue, which are typical symptoms for the action of cellulose biosynthesis inhibitors such as dichlobenil. During 24 h of treatment, no effects of quinclorac on cellulose deposition at the cell plates and parental walls of meristematic root cells were found. In contrast, 10 μM dichlobenil inhibited cellulose deposition in cell plate formation within 4 h of treatment. Concerning the hemicellulose constituents, increased staining for callose in areas of cell plates and parental cell walls was observed 24 h after treatment with 10 μM quinclorac. Concomitantly, (1→3),(1→4)β-glucan deposition in cell walls decreased. The latter may be an indirect effect of quinclorac through a stimulated production of cyanide from ethylene biosynthesis. In contrast with previous reports, no evidence that quinclorac, directly or indirectly inhibits cellulose biosynthesis in roots of susceptible grasses was found.     

Relationships between lipophilicity and the distribution of non-ionised chemicals in barley shoots following uptake by the roots

Determinations were made of the distribution of two series of non-ionised chemicals, ^O-methylcarbamoyloximes and substituted phenylureas, in barley shoots, following uptake by the roots from solution. The concentrations in basal and central shoot sections became constant after 24 to 48 h for all but the most lipophilic chemical studied, and were then greatest for the more lipophilic chemicals. Amounts in the leaves generally increased up to 72 or 96 h, when degradation balanced translocation. The accumulation of chemical in the lower section of shoots can be ascribed to a partitioning process similar to that in roots, the chemical being partitioned between the shoot and the xylem transpiration stream; this uptake could be estimated from the octan-1-01/water distribution coefficients, and was predicted to be greatest for compounds for which log K_ow=4. 5.     

A comparison of crop and non-crop plants as sensitive indicator species for regulatory testing

The effectiveness of regulatory non-target plant testing using crop species to predict the phytotoxicicity of herbicides to non-crop species was evaluated for eleven herbicides. These herbicides were representative of eight chemical classes and six modes of action. Data for non-crop plants from pre-emergence and post-emergence efficacy screening studies were compared with those for the most sensitive crop species defined by regulatory tests conducted to meet US EPA requirements. Testing under pre-emergence conditions for ten compounds indicated that for five of the compounds (K-815910, trifluralin, pyridyloxy A, pyridyloxy B and cyanazine), the most sensitive crop species was more sensitive than all the non-crop species evaluated. For metsulfuron-methyl, chlorimuron-ethyl, hexazinone and bromacil, only one of the non-crop species evaluated was more sensitive than the most sensitive crop species from regulatory tests. Data for the tenth compound, chloroacetamide, showed that four of 32 non-crop species tested in efficacy screens had at least one rate at which greater visual effects were observed than were observed for the most sensitive crop response in a regulatory test. The results of post-emergence exposure comparisons for five of the compounds (pyridyloxy A, cloransulam-methyl, chlorimuron-ethyl, cyanazine and hexazinone) indicated that the most sensitive crop species were more sensitive than all the non-crop species evaluated. Data for pyridyloxy B, metsulfuron-methyl and bromacil indicated that only one of the non-crop species evaluated was more sensitive than the most sensitive crop species. For trifluralin, three of the eight non-crop species were more sensitive than the most sensitive crop species. Data for K-815910 indicated that four of the fourteen non-crop species tested were marginally more sensitive than the most sensitive crop, but were within the same range of sensitivity. These results indicate that the current regulatory test batteries and methods using crop species effectively provide suitable sensitive indicator plants for the eleven diverse herbicides evaluated. This comparison indicates that crop species sensitivity to test substances is likely to be representative of non-crop herbaceous species response, regardless of chemical class, mode of action and magnitude or route of exposure.     

3种植物单根对土体残余抗剪强度影响的研究

课题组采用四联电动直剪仪对3种沙生植物重塑的根-土复合体及素土进行了直接剪切试验,研究其单根对提高土体残余抗剪强度的影响以及不同孔隙水承压条件下根-土复合体的残余抗剪强度变化.结果表明:浅层土压力下3种植物根-土复合体残余抗剪强度均大于素土,且柠条根系固土效果优于沙棘和白沙蒿;不同含水量梯度下,复合体存在最优含水量,该含水量条件下,根-土复合体强度达到最大值;模拟降雨条件下复合体各残余强度指标均大于非降雨条件下的指标,表现为模拟降雨条件下,3种植物复合体残余粘聚力增长率排序为柠条＞白沙蒿＞沙棘,模拟非降雨条件下排序为柠条＞沙棘＞白沙蒿.上述研究定量分析了3种植物根-土复合材料的力学特性,为水土保持树种的选择提供了理论依据,具有一定的应用价值.     

大豆根组织受尖孢镰刀菌侵染后基因表达反应的cDNA-AFLP分析

 为了阐明大豆受尖孢镰刀菌(Fusarium oxysporum,Fo)侵染后在基因转录水平上的感病反应,本研究用cDNA-AFLP方法,对Fo浸根接种后大豆根组织进行了基因转录谱的银染法检测分析。结果表明,在测定的大约1 000个大豆cDNA扩增片段(TDFs)中,16个是差异性表达的,其中9个受Fo诱导上调表达,7个被抑制下调表达。对这些差异性表达的TDFs进行克隆、测序及其同源性进行分析,发现其中6个具有已知或推断的生物学功能,包括钙调素结合蛋白(CaMBP)、BURP结构域蛋白和羟基多花碱-羟基烷宁转移酶等,其余10个功能未知。这些可能参与大豆感病性的差异性表达新基因片段的发现,为开展大豆感病性功能基因组学研究提供了材料。     

河北中部药用植物AM真菌生态学研究

2005年8月和10月,对河北省安国市境内种植的9种药用植物AM真菌侵染状况及与土壤因子的相关性进行了调查分析.结果表明,9种药用植物都能与AM真菌形成良好的共生关系,不同药用植物形成菌根的能力不同.形成的菌根包括重楼型(Paris-type)和疆南星型(Arum-type)2种类型.土壤碱解N与丹参和麻山药的孢子密度、北沙参菌丝定殖率和总定殖率呈显著正相关,与紫苑丛枝定殖率呈显著负相关.土壤速效P与丹参丛技定殖率、麻山药泡囊定殖率呈显著正相关,与桔梗孢子密度、白术泡囊定殖率呈显著负相关.土壤有机质与北柴胡孢子密度呈显著负相关.土壤pH与北沙参菌丝定殖率和总定殖率、北柴胡孢子密度呈显著负相关,与北沙参孢子密度呈显著正相关.     

Dynamics of uptake,translocation, and disappearance of thiabendazole and methyl-2-benzimidazolecarbamate in pepper and tomato plants

The dynamics of the uptake, translocation, and disappearance of thiabendazole (TBZ) and methyl-2-benzimidazolecarbamate (MBC), the fungicidal breakdown product of benomyl, were studied in tomato and pepper plants grown on nutrient solutions containing 0.5 ppm TBZ and 2.5 ppm MBC. Chemical analysis of pepper plants showed that the fungicides accumulated in the leaves only, where concentrations of 20 ppm TBZ and 60 ppm MBC were recorded. Thiabendazole was completely removed from pepper plants by acetone extraction, whereas MBC was only partially removed by acetone and the rest was weakly bound to the tissue and released by either methanolic HCl extraction or acid hydrolysis. The rate of disappearance of TBZ from pepper leaves was three to four times faster than that of MBC. Balance studies in tomatoes have shown an average disappearance rate of 13.5% per 10 days for MBC. 2-Aminobenzimidazole, the degradation product of MBC, was always detected but its concentration did not exceed 2% of that of the parent compound.     

Metabolic profiling in the roots of coffee plants exposed to the coffee root-knot nematode, Meloidogyne exigua

To understand the effect of nematode Meloidogyne exigua infestation on coffee plants, resistant and susceptible coffee seedlings were inoculated with second-stage juveniles of M. exigua, and root metabolites were studied for four time intervals at 0, 24, 48 and 96 h. During this important period for parasite establishment, the concentrations of phenols, carbohydrates, amino acids and alkaloids in the roots were measured, and hydrogen nuclear magnetic resonance spectra of the root extracts were used to identify and quantify other metabolites. One of the most striking changes was the concentration of fumaric acid on resistant plants, which varied from 59 μg g(of root)^?1 to 138 μg g(of root)^?1 during the first 24 h of the nematode inoculation. The same level of variation was observed much later (96 h) in susceptible plants. Similarly, formic and quinic acid concentrations increased more rapidly in the resistant plants compared to the susceptibles. Sucrose concentrations increased to 370 % in the first 48 h in the resistant plants but showed no significant variation in the susceptible plant. Besides, the concentration of alkaloids was much higher at 24 and 48 h in the susceptibles compared to the resistant plants. These results suggest that the higher production of sucrose as well as formic, fumaric and quinic acids, and the lower production of alkaloids by the resistant cultivar in the first 48 h after the nematode inoculation are associated with the resistance of coffee plants to M. exigua.     

"根康健"处理进出境园林种苗携带的植物寄生线虫

1999～2001年，对2年生感染根结线虫、双宫螺旋线虫的黄扬、冬青和榕树等17种苗木，5年生的景天等7种盆景的根部进行药剂处理。试验结果表明，使用“根康健”1：2倍液蘸根处理2h后，供试植物根上的外寄生性双宫螺旋线虫被全部杀死，36h后内寄生性根结线虫死亡率高达99％，25天后处理样中未检出任何活线虫。使用“根康健”1：4、1：6倍液进行药剂处理，25天后线虫死亡率分：到达87％～100％。“根康健”1：2倍液作为出入境观赏植物线虫处理剂，可以有效地杀死根组织内外的植物寄生线虫，满足苗木、盆景、花卉等的植物检疫要求。