INSECTICIDAL-ACTION STUDIES WITH BISDIMETHYL-AMINO FLUOROPHOSPHINE OXIDE CONTAINING 32PHOSPHORUS

The absorption of the systemic insecticide bisdimethylamino fluorophosphine oxide containing ³²P by plants has been studied, and where possible comparisons have been made with bisdimethylaminophosphonous anhydride.
The radio-oxide is absorbed by the roots of a broad-bean plant from culture solutions. The level of radioactivity in the plant increases as the solution is absorbed and is higher in the washed roots than in the rest of the plant. The radioactivity of the remaining culture solution decreases as more of it is taken up by the plants showing that the roots selectively absorb the oxide from solution. In this latter respect it differs from the anhydride which is selectively rejected at similar rates of transpiration. The material is absorbed more slowly by plants growing in soil than in sand.
An appreciable part of the oxide absorbed by the roots is given off as vapour by the leaves. The transpired material can be collected and shown to be radioactive and systemically insecticidal. Aphids feeding on treated plants contain radioactive material.
The oxide is less lipoid soluble than the anhydride and does not penetrate as readily into the leaves of the broad bean. Since it is also lost by vaporization from the plants only small amounts are translocated following leaf applications to beans, cabbages and hops.     

Contrasting silicon uptakes by coniferous trees: a hydroponic experiment on young seedlings

Silicon uptake by terrestrial plants impacts the Si land-ocean fluxes, therefore inducing significant modifications for biogeochemical cycle of Si. Understanding the mechanisms that control Si uptakes by forest vegetation is of great interest for the study of the global Si cycle as the world’s total forest area corresponds to about 30% of the land area. Our study compares Si uptake in controlled conditions by two coniferous species (Pseudotsuga menziensii and Pinus nigra) exhibiting contrasting Si uptake in the field. For this purpose, seedlings were grown for 11 weeks under controlled conditions in hydroponics with different Si concentrations (0.2 to 1.6 mM) in nutrient solutions. The Si concentrations were greater in Douglas fir leaves as compared with Black pine leaves and increased, depending on the Si concentration in the nutrient solution. According to mass balance, Si absorption seems to have been driven by passive Si transport at 0.2 mM Si (realistic concentration for forest soil solutions) and was rejective at higher Si concentrations in nutrient solution for both species. For this reason, we attributed the higher Si concentration in Douglas fir leaves to the greater cumulative transpiration of these seedlings. We suggest that contrasting transpiration rates may also play a key role in controlling Si accumulation in leaves at field scale.     

Studies in the Physiology of Lichens: With one Figure in the Text: Absorption and Utilization of Some Simple Organic Nitrogen Compounds by Peltigera polydactyla

Peltigera discs can accumulate relatively very large amountsof asparagine from solution by a process which involves theentry and accumulation of asparagine in the tissues as the completemolecule. Utilization of absorbed asparagine occurs at a relativelyslow rate and involves the preliminary deamidation of it toammonia. Asparagine absorption is completely inhibited by sodiumfluoride, and partially inhibited by glucose. Absorption isaccompanied by a release of ammonia in the medium and also byincreases in respiration rates and a change in R.Q. None ofthe absorbed asparagine can be washed out of the tissues. Discsalso show strong powers of absorption from solutions of glutamine,and glutamic and aspartic acids. There is more organic thaninorganic nitrogen in solution in the liquids available to thelichen in its habitat. The amounts of glucose and of phosphate which Peltigera andsome other lichens can accumulate from solution are also verylarge considering the slow growth-rates of these plants. Itis suggested that the possession of strong powers of absorptionof substances from solution may be a general characteristicof lichens and plants of similar habitats: it may representan adaptation to existence in barren conditions where the concentrationof nutrients in solution is very low. Utilization of absorbednutrients at a slow rate may be an adaptation to the need tosurvive long periods of starvation. The ecological implicationsof these suggestions are also discussed.     

Aluminium/silicon interactions in higher plants

Aluminium and silicon are usually abundant in soil mineral matter,but their availability for plant uptake is limited by low solubilityand, in the case of Al, high soil pH causes precipitation ofthe element in insoluble forms. Al toxicity is a major problemin naturally occurring acid soils and in soils affected by acidicprecipitation. Al has no known role in higher plants, and isgenerally known as a toxic element, whereas Si is generallyregarded as a beneficial element. Recently, it has been suggestedthat Al toxicity can be ameliorated by Si in a variety of animalsystems. In this review the evidence that amelioration of Altoxicity by Si can also occur in plants is assessed. At presentsuch amelioration has been shown in sorghum, barley, teosinte,and soybean, but not in rice, wheat, cotton, and pea. Plantspecies vary considerably in the amounts of Al and Si that theytransport into their tissues, and it seems that very high Siaccumulation and very high Al accumulation are mutually exclusive.The mechanisms considered for amelioration are: solution effects;codeposition of Al and Si within the plant; effects in the cytoplasmand on enzyme activity; and indirect effects. Key words: Aluminium, silicon, biomineralization, codeposition, toxicity, tolerance     

The effect of calcium bicarbonate on iron absorption and distribution byChrysanthemum morifolium, (Ram.)

Summary Plants grown for two weeks in high-bicarbonate nutrient solution with iron became chlorotic, absorbed less iron, and translocated a lower percentage of absorbed iron than did green plants grown under low bicarbonate with iron. Chlorotic plants, pretreated in low-bicarbonate solutions lacking iron, absorbed more iron and translocated a higher percentage to leaves than the green plants. Plants induced to chlorosis by high bicarbonate absorbed less iron after transfer to low-bicarbonate solution containing iron than did chlorotic plants pretreated with low-carbonate solution lacking iron. Initial localization of iron occurred in the roots. A considerable amount of the iron initially found on the roots was translocated to developing shoots over a nine-week period unless the plants were grown in high bicarbonate solutions. More iron was translocated from roots of plants in minus-iron solutions following initial absorption than when iron was supplied in the nutrient solutions. Journal Series Paper736. University of Georgia, College of Agriculture Experiment Stations, College Station, Athens, Ga. 30601.     

A precise spacing between the NPA domains of aquaporins is essential for silicon permeability in plants

The controversy surrounding silicon (Si) benefits and essentiality in plants is exacerbated by the differential ability of species to absorb this element. This property is seemingly enhanced in species carrying specific nodulin 26‐like intrinsic proteins (NIPs), a subclass of aquaporins. In this work, our aim was to characterize plant aquaporins to define the features that confer Si permeability. Through comparative analysis of 985 aquaporins in 25 species with differing abilities to absorb Si, we were able to predict 30 Si transporters and discovered that Si absorption is exclusively confined to species that possess NIP‐III aquaporins with a GSGR selectivity filter and a precise distance of 108 amino acids (AA) between the asparagine–proline–alanine (NPA) domains. The latter feature is of particular significance since it had never been reported to be essential for Si selectivity. Functionality assessed in the Xenopus oocyte expression system showed that NIPs with 108 AA spacing exhibited Si permeability, while proteins differing in that distance did not. In subsequent functional studies, a Si transporter from poplar mutated into variants with 109‐ or 107‐AA spacing failed to import, and a tomato NIP gene mutated from 109 to 108 AA exhibited a rare gain of function. These results provide a precise molecular basis to classify higher plants into Si accumulators or excluders.     

The Effect of Micro-organisms on the Absorption of Inorganic Nutrients by Intact Plants: II. UPTAKE AND UTILIZATION OF PHOSPHATE BY BARLELY PLANTS GROWN UNDER STERILE AND NON-STERILE CONDITIONS

The uptake of phosphate by barley plants grown under sterileand non-sterile conditions has been compared from solutionsranging in concentration between 0.001 to 10.0 ppm P. If specialprecautions are not taken to exclude microorganisms their activityon or in plant roots greatly modifies the absorption and utilizationof phosphate in plants, especially when the external concentrationis low. More phosphate is incorporated into nucleic acids, phospholipids,and phosphoproteins in the roots; at 0.001 ppm P these compoundsaccount for over 60 per cent of the phosphate absorbed comparedwith about 15 per cent in plants grown under sterile conditionsand even at 1.0 ppm P there is a twofold difference. The immobilizationof phosphate in the roots reduces its transfer to the shoots;at 0.001 ppm P, 2 as compared with 20 per cent of the phosphateabsorbed is transferred to the shoots. This effect decreaseswith increasing concentration but small differences are stillapparent up to about 0.5 ppm P. A further effect of micro-organisms is apparent when plantsare transferred from dilute solutions to phosphate-free solutions.Under non-sterile conditons there is an almost tenfold increasein the loss to these solutions of previously absorbed phosphate. It is evident that conclusions on the mechanism of absorptionof phosphate, based on experiments in which the actions of micro-organismshave been ignored, require reinvestigation.     

硅在植物体内的分布和吸收及其在病害逆境胁迫中的抗性作用

硅在地壳中含量位居第二位,尽管还没有被列为植物生长的必需营养元素,但它在促进植物生长发育和营养吸收、提高植物对非生物逆境胁迫和生物逆境胁迫的抗性等方面都具有重要作用。综述了近些年来国内外关于硅在植物体内的分布、吸收及其生理效应,重点介绍了硅在病害逆境胁迫中的抗性作用机理。高等植物以单硅酸[Si(OH)4]的形式吸收硅,存在硅的主动吸收和被动吸收机制。硅主要沉积在叶片及叶鞘表皮细胞,形成硅化细胞和角质-硅双层结构,能增强寄主植物细胞壁的机械强度和稳固性,从而延缓和抵御病菌的侵入和扩展。更多的证据表明,硅处理能增加植物叶片保护酶(过氧化物酶、多酚氧化酶、苯丙氨酸解氨酶等)活性和诱导寄主产生次生代谢抗性物质(如植保素、多酚类化合物、木质素),从而激活植物的防御系统,增强对病原菌的抵抗能力。分子水平上的研究显示,硅能诱导与植物防御机制相关的基因表达,参与抗病信号分子(如水杨酸、茉莉酸和乙烯)在信号传导中的作用。     

硅和干旱胁迫对水稻叶片光合特性和矿质养分吸收的影响

硅被认为是植物生长的有益元素,它能增强植物对非生物逆境和生物逆境胁迫的抗性。以抗旱性不同的一对水稻近等基因系w-14-和w-20为实验材料,采用盆栽实验,研究了干旱胁迫下硅处理对水稻生长性状、光合生理特性和矿质养分吸收的影响。结果表明,在正常水分条件下硅处理对水稻的生长及生理特性没有明显影响。干旱胁迫显著降低水稻植株的生长,叶绿素含量、叶绿素荧光参数Fv/Fm及Fv/F0值显著降低,光合作用受到明显抑制。加硅能提高干旱胁迫条件下水稻植株的生物量、水分利用效率、叶片叶绿素含量、净光合速率和蒸腾速率,而气孔导度和细胞间隙CO2浓度则下降。无论干旱与否,施硅后水稻的叶片硅含量均显著上升。两个水稻品系叶片的无机离子含量在干旱胁迫条件下均呈显著增加的趋势,而硅处理后材料w-14的叶片K+、Na+、Ca2+、Mg2+、Fe3+含量分别降低16.38%,24.50%,19.70%,21.52%,18.58%,w-20则分别降低11.64%,12.11%,16.06%,11.11%和19.15%,并使之回复到与对照更接近的水平。研究结果表明了硅提高水稻植株的抗旱性与光合作用的改善和矿质养分的调节有关。     

Effect of replacing nutrient potassium by sodium on uptake and distribution of sodium in tomato plants

Summary Tomato plants (Lycopersicon esculentum cv. Amberley Cross) were grown in a series of nutrient solutions in which 0, 60, 90, 95, 98 and 99 per cent of the K was replaced by Na. The plants selectively absorbed K relative to Na from the nutrient solutions and transported K to the shoots in preference to Na. In the nutrient solution having the highest K/Na ration most of the Na taken up by the plants accumulated in the roots, but as the K was progressively replaced by Na an increasing proportion of the total Na absorbed was transported to the leaves. Sodium was present at up to 2.4 per cent of the dry wt of whole, fully-expanded leaves without there being any apparent visual signs of damage or reduction in the rate of growth of the plants. On closer examination it was found that most of the Na transported to the leaves was excluded from the laminar tissue and accumulated in the adjacent petioles. The ability of the roots and petioles to retain large amounts of Na depended on an adequate supply of K to the plants.     

The absorption and transport of manganese by perennial ryegrass and white clover as affected by silicon

Summary The effects of added silicon on the absorption and transport of manganese in perennial ryegrass (an accumulator of Si) were determined and compared with those found in white clover (which has restricted Si uptake). The plants were grown in flowing solution culture in two experiments with Si in the nutrient solution maintained at 0, 10 or 20 mgl⁻¹ and Mn at 0.005 mgl⁻¹. By the final harvests, the plants contained concentrations of both Mn and Si that were comparable to those found in field-grown plants. In common with other findings, white clover had very much lower concentrations of Si in both shoots and roots than did ryegrass but there was no effect of Si treatment on the growth of either species. In both species, the concentrations of Mn were initially greater in roots than in shoots, but values in both plant parts decreased with time and by the final harvests, were similar. The rates of absorption of Mn by roots and its subsequent transport to shoots were also similar in both species. In contrast to findings for other species in other studies based on conventional solution culture, there was no effect of added Si on either absorption or transport of Mn in clover or ryegrass. It was therefore concluded that any effect of Si on the behaviour of Mn in plants must result from changes in distribution and partitioning within leaf tissues and cells.     

Spectrophotometric titrations of micellar Schiff''s bases prepared from pyridoxal 5′-phosphate

Electron absorption and equilibrium of the Schiffs bases prepared between pyridoxal 5′-phosphate (PLP) and dodecylamine (DODA) or some other shorter chain amines have been studied in nonionic and cationic micellar solutions with various pH of the bulk solution. In the presence of the nonionic (Triton X-100) micelles the Schiffs bases formed between PLP and DODA were embedded into the micelles because the absorption occured at 335 nm, indicative of the nonpolar milieu. This absorption was constant at pH 5–10. At pH 3–5, the tautomeric form absorbing at 415 nm appeared. This resembles the titration of glycogen phosphorylate or that of Schiffs bases in methanol. Short chain amines absorbed at 415 nm, which is typical of Schiffs bases in aqueous solutions. Tryptophan also absorbed first at 415 nm but the absorption changed to 325 nm with a half-time of ～20 min. This was interpreted as being due to formation of the cyclic structure catalysed by micelles. The pH-dependent equilibrium constant of the reaction between PLP and DODA in Triton X-100 solution had a maximum at pH9, the value being 3500 M^?1, about ten times greater than the value of ethylamine at the same pH. Spectral properties of PLP-DODA imines in the cationic micelles (cetyltrimethylammonium bromide) resembled those in the nonionic micelles, except that at low pH the absorption peak in the 415 nm region did not appear. The equilibrium constant of PLP-DODA had maximum at pH 9, the value being as high as 118000 M^?1. Different properties of nonionic and cationic micelles and the design of micellar model systems of PLP enzymes are discussed.     

THE APHICIDAL ACTION OF SOME SYSTEMIC INSECTICIDES APPLIED TO SEEDS

When large seeds such as broad bean are soaked in certain systemic insecticides, notably demeton, the plants which they produce are toxic to aphids. With small seeds the effect is difficult to detect.
Experiments with demeton solutions and broad beans show that equal quantities of water and demeton are absorbed. Beans vary greatly in the rate at which they absorb solution, so, to reduce variations, about 24 hr. soaking is necessary. The insecticidal activity of the plant is directly related to the quantity of solution absorbed by the seed. Larger bean seeds absorb more solution than small beans and the plants are more toxic. After short periods of soaking (4 hr.) there is more insecticide in the seed coat than in the cotyledons, after 24 hr. there is more in the cotyledons. Some of the toxic material in the seed reaches the growing plant via the soil and roots. The material in the cotyledons can pass directly to the growing plant. As some of the material absorbed by the seed passes into the soil, any factors such as an increase in soil volume or heavy watering which tend to dilute the insecticides reduce the quantity of toxic material reaching the plant. The same quantity of demeton is more effective when absorbed by a seed than when watered on to the soil around it. Seeds soaked in insecticide, dried, and stored for one month produced plants toxic to aphids.     

离子吸收分布与几种荒漠植物适应性的关系

用压力室灌流挤压法结合原子吸收分光光度计测定了胡杨、沙枣、柽柳、梭梭和花棒等5种荒漠优势植物组织以及细胞内和质外体溶液中K+、Na+含量,并用TPS-1型光合蒸腾测定系统和露点微伏压计测定了叶片(同化枝)的蒸腾速率和组织渗透势,以分析荒漠植物离子吸收特点与其适应性的关系。结果表明:5种植物叶片(同化枝)中K+含量差异较小,但Na+含量却有极显著差异,其中梭梭Na+含量最高、胡杨和柽柳次之、花棒和沙枣相对较低,且梭梭和柽柳的根系和组织细胞膜对Na+也具有更高的透性。另外,实验结果还显示组织Na+含量与组织渗透势和蒸腾失水率均呈显著负相关,即Na+的吸收、积累可能在渗透调节和减少水分散失中具有重要作用。由此可见,梭梭和柽柳能够通过大量吸收和积累无机离子来降低渗透势、增强吸水力,同时减少蒸腾失水,具有很强的荒漠环境适应能力;而胡杨蒸腾耗水量较大、花棒和沙枣生理吸水的动力不足,与梭梭和柽柳相比,其荒漠环境适应能力相对较弱。     

Role of leaf apoplast in silicon-mediated manganese tolerance of Cucumis sativus L.

Silicon (Si) supplied as sodium silicate (1·8 mm ) clearly decreased symptoms of manganese (Mn) toxicity in Cucumis sativus L. (cv. Chinesische Schlange) grown in nutrient solution with low to elevated Mn concentrations (0·5–1000 µm ). Despite approximately the same total Mn content in the leaves, plants not treated with Si had higher Mn concentrations in the intercellular washing fluid (IWF) compared with plants treated with Si, especially in the BaCl₂‐ and DTPA‐exchangeable fraction of the leaf apoplast. The Mn concentration of the IWF correlated positively with the severity of Mn‐toxicity symptoms and negatively with the Si supply. Furthermore, in Si‐treated plants less Mn was located in the symplast (< 10%) and more Mn was bound to the cell wall (> 90%) compared with non‐Si‐treated plants (about 50% in each compartment). Manganese present in Si‐treated plants is therefore less available and for this reason less toxic than in plants not treated with Si. It is concluded that Si‐mediated tolerance of Mn in C. sativus is a consequence of stronger binding of Mn to cell walls and a lowering of Mn concentration within the symplast. These results support the role of Si as an important beneficial element in plant nutrition.     

Study on the Absorbed Fingerprint-Efficacy of Yuanhu Zhitong Tablet Based on Chemical Analysis,Vasorelaxation Evaluation and Data Mining

Yuanhu Zhitong Tablet (YZT) is an example of a typical and relatively simple clinical herb formula that is widely used in clinics. It is generally believed that YZT play a therapeutical effect in vivo by the synergism of multiple constituents. Thus, it is necessary to build the relationship between the absorbed fingerprints and bioactivity so as to ensure the quality, safety and efficacy. In this study, a new combinative method, an intestinal absorption test coupled with a vasorelaxation bioactivity experiment in vitro, was a simple, sensitive, and feasible technique to study on the absorbed fingerprint-efficacy of YZT based on chemical analysis, vasorelaxation evaluation and data mining. As part of this method, an everted intestinal sac method was performed to determine the intestinal absorption of YZT solutions. YZT were dissolved in solution (n = 12), and the portion of the solution that was absorbed into intestinal sacs was analyzed using rapid-resolution liquid chromatography coupled with quadruple time-of-flight mass spectrometry (RRLC-Q-TOF/MS). Semi-quantitative analysis indicated the presence of 34 compounds. The effect of the intestinally absorbed solution on vasorelaxation of rat aortic rings with endothelium attached was then evaluated in vitro. The results showed that samples grouped by HCA from chemical profiles have similar bioactivity while samples in different groups displayed very different. Moreover, it established a relationship between the absorbed fingerprints and their bioactivity to identify important components by grey relational analysis, which could predict bioactive values based on chemical profiles and provide an evidence for the quantification of multi-constituents.     

Nitrate reduction in the roots and shoots of wheat seedlings

Summary Intact wheat seedlings cultured in high nitrate solutions (high-NO ₃ ^- cultures) reduced NO ₃ ^- when placed for 24 hr in dilute CaSO₄ solutions although they leaked NO ₃ ^- back to solution during this period. Most of the reduction seemed to occur in shoots since in parallel experiments detached shoots reduced nearly as much of the previously absorbed NO ₃ ^- as intact cultures. Detached roots leaked greater quantities of NO ₃ ^- back to solution than did intact cultures, and failed to reduce any of their previously absorbed NO ₃ ^- during the experimental period. Seedlings of identical age cultured without a nitrogen source and rich in carbohydrate reserves (low-N cultures) rapidly absorbed NO ₃ ^- from dilute Ca(NO₃)₂ solutions and reduced 80% of that absorbed. Detached low-N roots also absorbed NO ₃ ^- and reduced 40% of that absorbed. Total NO ₃ ^- reduction by intact low-N cultures over the 24-hr period was comparable to that of high-NO ₃ ^- cultures in spite of the fact that in vitro nitrate reductase activity of the former did not reach the levels found initially or at the end of the period in the latter, and that the total NO ₃ ^- absorbed by low-N cultures was less than that initially present in high-NO ₃ ^- cultures.Paper No. 3155 of the Journal Series of the North Carolina State University Agricultural Experiment Station, Raleigh, North Carolina. These investigations were supported by the U.S. Atomic Energy Commission Contract No. At-(40-1)-2410.     

The absorption of manganese (III) in oat plants

Summary The absorption of Mn (III)-pyrophosphate complex by oat plants, cultured in a liquid medium with nutrient solutions, has been studied. The results indicate that the Mn supplied in this way is accumulated in the plant in a much more intense form. The root is the organ which through its Mn content best reflects the concentration of Mn in the medium in a directly proportional relationship, at the same time that the inflorescence is able to regulate the uptake of the element. It appears that the Mn (III)-pyrophosphate complex is less active compared with Mn (II) as ion, since with the same concentration in the plant less dry matter is produced. It is possible that it remains in the plant, at least partially, in the complex form. Nevertheless, the inflorescence does not distinguish between both forms of the element, as if in this organ they were rendered, or arrived in the same form. An antagonism between the Mn supplied and the Fe content in various parts of the plant is observed, especially when the Mn is added in the form of complex; except that, as noted above, the inflorescence and in this case also the roots does not distinguish between the two forms of the nutrient. re]19751218     

Sugar Absorption and Surface Carbohydrase Activity of Peltigera polydactyla (Neck.) Hoffm.

A method suitable for the study of the physiology of absorptionof substances from solution and of respiration of Peltigerapolydactyla was elaborated making use of discs of tissue whichcould be floated on solutions. The rate of absorption of hexosesugars by the discs was sensitive to temperature, the presenceof inhibitors, such as sodium fluoride and silver nitrate, butrelatively insensitive to hydrogen ion concentration. Glucosewas absorbed preferentially to fructose from equimolar solutions.Absorption of sugar from sucrose solutions involved inversionby an enzyme system held on the cell surface. This system wasrelatively unaffected by exposure to moderate temperature, tosodium fluoride or silver nitrate but sensitive to hydrogenion concentration. Sucrose did not seem to be absorbed as suchand the glucose was absorbed preferentially from the productsof inversion. All parts of the thallus were equally effectivein inversion but absorption was mainly into the algal layer.The entry into the tissues was associated with a respiratoryrise.