Toxicity of Lanthanum Against Rhizoctonia solani and Its Effect on Disease-Related Enzymes

Thoroughexperimentsandpracticeaboutrare earth(RE)elementshavebeenconductedsince 1970.ScientistsinChinahavesolvedaseriesofkey technologiesandappliedREelementssuccessfullyin agricultureproduction,andmadeChinabecomethe firstcountryapplyingREasacommercialprod…     

Toxicity of Lanthanum to Pathogenic Fungi and Its Morphological Characteristics

Rare earth (RE) ,a kind of natural mineral hasbeen used as a beneficial element to crops for quite alongti me . Withthe solution of a series of keytechnolo-gies such as extraction,separation of radioactive ingre-dients ,sanitary toxicology,and environmental safety,China became the first countryto apply commercial REproducts asfertilizer or growthsti mulatorin agriculture ,which produced considerable economic and social ben-efits[1 ,2].RE has been found to have some controllingeffects on many…     

Chitinolytic activity of an endophytic strain of Bacillus cereus

Bacillus cereus strain 65, previously isolated as an endophyte of Sinapis, was shown to produce and excrete a chitinase with an apparent molecular mass of 36 kDa. The enzyme was classified as a chitobiosidase because it was able to cleave diacetylchitobiose (GlcNAc)2 from the non-reducing end of trimeric chitin derivatives. The chitinase exhibited activity over the pH range 4.5-7.5 and was stable between pH 4.0 and 8.5. The enzyme had an isoelectric point of 6.4. Application of B. cereus 65 directly to soil significantly protected cotton seedlings from root rot disease caused by Rhizoctonia solani.     

Effects of La^3＋ on ATPase Activities of Plasma Membrane Vesicles Isolated from Casuarina Equisetifolia Seedlings under Acid Rain Stress

Asamainkindofmembranetransporter ,plasmamembraneATPasesfacilitatethetransportofminerals ,sugars,metabolites ,andothercompoundsacrossthemembraneofthecells ,onlybywhichcouldplantcellscommunicatewithenvironmenttotransfersubstanceandinformation ,whichisessentialforplantgrowthandcellularhomeostasis[1] .Astheexperimentmateri als ,thehighlypurifiedplasmamembranevesiclesfromCasuarinaequisetifoliaseedlingscultivatedunderartificialacidrainstress ,wereisolatedbyaqueoustwo-phasepartitioningmethods .Thest…     

Effect of Lanthanum on Mycelium Growth and Some Pathogenic Factors

Three soil-transmitted pathogenic fungi including Rhizoctonia solani, Fusarium solani, and Pythium sp. were selected to investigate the effect of lanthanum on their growth and the pathogenic enzymes using liquid culture. Variance analysis shows significant differences among treatments with different concentrations of lanthanum （Rhizoctonia solani F = 6.75 〉 F0.01= 5.99; Fusarium solani F = 18.1 〉 F0.01 = 5.99, Pythium sp. F = 23.29 〉 F0.01 = 5.99）. The inhibitory effect of lanthanum on pathogenic fungi increased with an increase in La concentration. The activities of the three pathogenic enzymes per gram mycelium were promoted remarkably. However, the quantity or the activities of the total enzymes were inhibited because of the strong inhibition of mycelium growth by lanthanum. Meanwhile, the effect of lanthanum on toxins of pathogenic fungi were studied using the seed germination experiment. Toxins of pathogenic fungi are influenced by lanthanum and the virulence decreases significantly with the increase of lanthanum concentration.     

Bcl-2 inhibits cell death of serum-free mouse embryo cells caused by epidermal growth factor deprivation

China has accumulated a rich body of empirical knowledge of the use of medicinal plants for the treatment of various diseases throughout its long history. Chemical studies on Chinese medicinal plants provide a valuable material base for the discovery and development of new drugs of natural origin. In this article recent chemical work on various Chinese medicinal plants is reviewed, including Mussaenda pubescens (Rubiaceae), Isatis indigotica (Cruciferae), Euphorbia fischeriana, and E. ebracteolata (Euphorbiaceae), and Stemona species (Stemonaceae). The structural diversity of the medicinal chemical constituents of the above plants is discussed.     

Mechanism of Effect of Lanthanum Nitrate on Vigor of Aged Rice Seeds

Ｓｅｅｄｓｅａｒｌｙｄｅｇｅｎｅｒａｔｅｄｏｒａｇｅｄｂｙｕｎ ｓｕｉｔａｂｌｅｃｕｌｔｉｖａｔｉｏｎｏｒｕｎｓｔｏｒａｇｅｔｅｃｈｎｉｑｕｅｓｍａｙｒｅｓｕｌｔｉｎｄｅｃｒｅａｓｉｎｇｏｆｓｅｅｄｖｉｇｏｒａｎｄｏｆｔｈｅｃｒｏｐｓｏｕｔｐｕｔ,ｅｓｐｅｃｉａｌｌｙｆｏｒｒｉｃｅ.Ｒａｒｅｅａｒｔｈｓａｃｃｅｌｅｒａｔｅｔｈｅｇｅｒｍｉｎａｔｉｏｎａｎｄｇｒｏｗｔｈｏｆｔｈｅｃｒｏｐｓ ,ｓｕｃｈａｓｒｉｃｅ ,ｗｈｅａｔ,ｂａｒｌｅｙ ,ｖｅｇ ｅｔａｂｌｅｓａｎｄｏｉｌｐｌａｎｔｓ[1～ 3] .Ｔｈｅｓｔ…     

Effect of plant residues on the parasitic activity of soilborne pathogens and the saprophytic microflora of the soil. I. Model trials with Rhizoctonia solani Kühn (author's transl)]

1. In glass-house trials the influence of residues of clover, grass, and mixtures (1:1) of them added to natural and partially sterilized loam soil upon the parasitic activity of Rhizoctonia solani and the soil micro-organisms and their activity was analyzed. 2. Burying of plant residues (1%) increased the content of organic substance in soil for 8 weeks and longer. 3. The soil reaction (pH) was not noteworthy affected by application of clover or grass residues. 4. However, the populations of bacteria and actinomycetes were increased, especially by adding clover dried. In natural soil, the maximum of stimulation was reached later than in soil sterilized. Adding of grass and roots of grass enlarged the spectrum of fungi observed in the soil amended. Roots of grass stimulated the cellulose-decomposing organisms remarkably. 5. The activity of dehydrogenase (AD) was influenced in different manner: in natural soil fresh clover, grass, mixtures of them, and clover dried increased, and fresh roots of clover, grass, and mixtures of them diminished AD; in soil sterilized the most variants stimulated this activity. 6. All plants residues increased the cellulolytic activity of soil for a long time, but in sterilized soil this effect reached its maximum earlier than in natural soil amended and did not last so long, too. 7. The possible explanations for the inhibition of parasitic activity of Rhizoctonia solani caused by burying plant residues are discussed.     

Lysine synthesis and catabolism are coordinately regulated during tobacco seed development

The regulation of synthesis and accumulation of the essential amino acid lysine was studied in seeds of transgenic tobacco plants expressing, in a seed-specific manner, two feedback-insensitive bacterial enzymes: dihydrodipicolinate synthase (EC 4.2.1.52) and aspartate kinase (EC 2.7.2.4). High-level expression of the two bacterial enzymes resulted in only a slight increase in free lysine accumulation at intermediate stages of seed development, while free lysine declined to the low level of control plants toward maturity. To test whether enhanced catabolism may have contributed to the failure of free lysine to accumulate in seeds of transgenic plants, we analyzed the activity of lysine-ketoglutarate reductase (EC 1.5.1.7), an enzyme that catabolizes lysine into saccharopine. In both the control and the transgenic plants, the timing of appearance of lysine-ketoglutarate reductase activity correlated very closely with that of dihydrodipicolinate synthase activity, suggesting that lysine synthesis and catabolism were coordinately regulated during seed development. Notably, the activity of lysine-ketoglutarate reductase was significantly higher in seeds of the transgenic plants than in the controls. Coexpression of both bacterial enzymes in the same plant resulted in a significant increase in the proportions of lysine and threonine in seed albumins. Apparently, the normal low steady-state levels of free lysine and threonine in tobacco seeds may be rate limiting for the synthesis of seed proteins, which are relatively rich in these amino acids.     

Effect of La~(3+)on Activities of Antioxidant Enzymes in Wheat Seedlings under Mercury Stress

Ｓｉｎｃｅ 1 970ｓ ,ＲＥＥｓ (ｒａｒｅｅａｒｔｈｅｌｅｍｅｎｔｓ)ｆｅｒｔｉｌｉｚｅｒｈａｓｂｅｅｎｅｘｔｅｎｓｉｖｅｌｙｒｅｓｅａｒｃｈｅｄｏｎａｐｐｌｉｃａｔｉｏｎｉｎａｇｒｉｃｕｌｔｕｒｅａｎｄｔｈｅｉｒｐｈｙｓｉｏｌｏｇｉ ｃａｌｅｆｆｅｃｔｓ .Ｔｈｅｒｅｗｅｒｅｍａｎｙｅｘｐｅｒｉｍｅｎｔａｌｄａ ｔａ .ＳｏｍｅｒｅｓｅａｒｃｈｅｒｓｒｅｐｏｒｔｅｄｔｈａｔＲＥＥｓｃａｎｎｏｔｏｎｌｙｐｒｏｍｏｔｅｐｌａｎｔｇｒｏｗｔｈ ,ｂｕｔａｌｓｏｅｎ ｈａｎｃｅｔｈｅｓｔｒｅｓｓｔｏｌｅｒａｎｃｅ .…     

Nitric Oxide Alleviates Oxidative Stress Caused by Lanthanum in Rice Leaves

The effect of NO on lanthanum-induced antioxidant activities in rice was evaluated. The results showed that the uptake and translocation of La from root to shoot were obviously inhibited by 10μmol·L^-1 sodium nitropmsside （SNP）, a donor of NO, in the seedlings grown in Mura B nutrient solution with 100μmol·L^-1 La. Although the content of ascorbate acid （AsA） were scarcely affected by La or NO in our experiment, La decreased significantly the activity of SOD and content of GSH, while promoted H202 content in leaves. Furthermore, NO blocked these La effects. Taken together, the results suggested that NO relieved La toxicity in rice. A possible role for NO effects on antioxidant activity was discussed.     

Expression of functional oat phytochrome A in transgenic rice

To investigate the biological functions of phytochromes in monocots, we generated, by electric discharge particle bombardment, transgenic rice (Oryza sativa cv Gulfmont) that constitutively expresses the oat phytochrome A apoprotein. The introduced 124-kD polypeptide bound chromophore and assembled into a red- and far-red-light-photoreversible chromoprotein with absorbance spectra indistinguishable from those of phytochrome purified from etiolated oats. Transgenic lines expressed up to 3 and 4 times more spectrophotometrically detectable phytochrome than wild-type plants in etiolated and green seedlings, respectively. Upon photo-conversion to the far-red-absorbing form of phytochrome, oat phytochrome A was degraded in etiolated seedlings with kinetics similar to those of endogenous rice phytochromes (half-life approximately 20 min). Although plants overexpressing phytochrome A were phenotypically indistinguishable from wild-type plants when grown under high-fluence white light, they were more sensitive as etiolated seedlings to light pulses that established very low phytochrome equilibria. This indicates that the introduced oat phytochrome A was biologically active. Thus, rice ectopically expressing PHY genes may offer a useful model to help understand the physiological functions of the various phytochrome isoforms in monocotyledonous plants.     

Microcystin uptake inhibits growth and protein phosphatase activity in mustard (Sinapis alba L.) seedlings

Mustard (Sinapis alba L.) seeds were cultivated for seven days on a solid nutrient medium supplemented with 040 microg microcystin-RR per ml. Microcystin-RR affected seedling growth (IC50 0.8 microg/ml) and microcystin concentrations > or =5.0 microg/ml produced malformed plants. The inhibition of protein phosphatase 1 and 2A activity correlated with the growth inhibition. The seedlings were also shown to take up 3H-dihydromicrocystin-LR derived radioactivity up to a level corresponding to ca. 80 ng toxin per mg plant protein.     

稀土对水稻种子活力及抗重金属污染的影响

水稻种子经稀土元素La或Ce处理后,发芽势、发芽率、发芽指数、幼苗生长速度、活力指数都明显增加,田间的生长速度、产量甚至品质也显著提高,收获的籽粒中重金属Hg、Cd、Cr、Pb含量大幅降低,从而全面提高了种子活力。     

稀土在杜仲上的应用研究

选用易于观察研究的杜仲幼苗、幼林、种子、扦插用的枝条作为试验材料,研究了稀土在杜仲上的应用效果和施用技术,并研制了一种高效价廉的林用促长剂     

Gene transfer via pollen-tube pathway for anti-fusarium wilt in watermelon

In order to obtain transgenic fusarium wilt resistant watermelon plants, squash DNA was introduced into the ovaries of watermelon plants via the pollen-tube pathway. The introduction of foreign genes into ovaries was accomplished using co-transformation with the CaMV35S-GUS as a marker. Transformed watermelon plants contained integrated copies of the GUS activity and the seeds of transformed progeny produced a blue color when stained with 5-bromo-4-chloro-3-indolyl glucuronide, whereas seeds from untransformed control plants did not. Of 200 transformed seedlings, ten were wilt resistant. The presence of the GUS activity in the genome of stable transgenic seedlings was confirmed by Southern blot analysis. Furthermore, the generation of random amplified polymorphic DNA (RAPD) fingerprints using primers with embedded restriction sites showed amplification products unique to these transgenic plants. Primers OPA-1 and OPA-9 gave distinct band patterns of genomic DNA using the polymerase chain reaction.     

Molecular cloning, structural analysis, and expression in Escherichia coli of a chitinase gene from Enterobacter agglomerans

The gene chiA, which codes for endochitinase, was cloned from a soilborne Enterobacter agglomerans. Its complete sequence was determined, and the deduced amino acid sequence of the enzyme designated Chia_Entag yielded an open reading frame coding for 562 amino acids of a 61-kDa precursor protein with a putative leader peptide at its N terminus. The nucleotide and polypeptide sequences of Chia_Entag showed 86.8 and 87.7% identity with the corresponding gene and enzyme, Chia_Serma, of Serratia marcescens, respectively. Homology modeling of Chia_Entag's three-dimensional structure demonstrated that most amino acid substitutions are at solvent-accessible sites. Escherichia coli JM109 carrying the E. agglomerans chiA gene produced and secreted Chia_Entag. The antifungal activity of the secreted endochitinase was demonstrated in vitro by inhibition of Fusarium oxysporum spore germination. The transformed strain inhibited Rhizoctonia solani growth on plates and the root rot disease caused by this fungus in cotton seedlings under greenhouse conditions.     

The somatostatin analogue octreotide protects against ethanol-induced microcirculatory stasis and elevated vascular permeability in rat gastric mucosa

The plant pathogenic isolate RI-64 of anastomosis group 4 of Rhizoctonia solani possesses three linear DNA plasmids (pRS64-1, -2, and -3). Unique poly(A)- RNA, 0.5 kb in length and hybridizable with the pRS64 DNAs was found in mycelial cells of the isolate RI-64. The overall homology at the nucleotide level between pRS64-1, -2, and -3, and the cDNA prepared from the poly(A)- RNA was 100%, 73%, and 84%, respectively. The open reading frames found in pRS64-1, -2, and -3 (ORF1-1, ORF2-1, and ORF3-1) are 68 amino acids long. The amino acids sequence showed no significant homology with known proteins. Extracts from Escherichia coli cells expressing ORF1-1 contain a specific protein of 7 kDa. Antisera raised against the ORF1-1 product obtained from E. coli cells cross-reacted with the specific proteins found in the mycelia. The results indicate that the DNA plasmids found in R. solani contain a sequence that encodes a specific protein which may be involved in determination of plant pathogenicity.     

Effects of Lanthanum on Redox Systems in Plasma Membranes of Casuarina equisetifolia Seedlings Under Acid Rain Stress

Theplasmamembraneisapenetrablebarrier ,whichcancontroltheexchangeofsubstancesacrossmembranesincells ,andalsoistheintermediumandreceptorofenergyorinformationtransferencebetweencellsandenvironment.Theplasmamembraneredoxsystem(PMRS)meanstheelectrontransferchainsonplasmamembrane .Owingtohavethepossibilityofejectingprotons ,energizingplasmamembraneandhavingthefunctionofacceleratingtransportationofsoluteacrossmembrane ,theplasmamembraneredoxsystemswerepaidmuchattentionto[1] .Acidrainisoneofthemost…     

Foliar application of rare earth elements on soybean(Glycine max(L)):Effects on biometrics and characterization of phytotoxicity

This study aims at investigating the effects of foliar application of aqueous solutions of La~(3+)and Ce~(3+)nitrates on soybean plants(Glycine max).First,we observe that Triton HW 1000 surfactant at 0.01 vol%reduces droplets contact angle and increases their drying time.Under greenhouse conditions,the foliar treatments do not affect chlorophyll content,plant height,number of leaves,number of pods,number of seeds per pod,and average seed weight.However,the treatments induce phytotoxicity since foliar injuries appear after the spraying.Microprobe X-ray fluorescence spectroscopy combined to scanning electron microscopy shows that the leaf lesions are positively correlated to accumulation of Ce and La on the leaf surface and also promote structural alteration to the epidermal cells.X-ray absorption near edge structure shows that the La and Ce nitrates are partially bio transformed into oxides by the leaves which might explain the harmful effects.