Improvement of cotton fiber quality by transforming the<Emphasis Type="Italic"> acsA</Emphasis> and<Emphasis Type="Italic"> acsB</Emphasis> genes into<Emphasis Type="Italic"> Gossypium hirsutum</Emphasis> L. by means of vacuum infiltration

A novel method for the genetic transformation of cotton pollen by means of vacuum infiltration and Agrobacterium-mediated transformation is reported. The acsA and acsB genes, which are involved in cellulose synthesis in Acetobacter xylinum, were transferred into pollen grains of brown cotton with the aim of improving its fiber quality by incorporating useful prokaryotic features into the colored cotton plants. Transformation was carried out in cotton pollen-germinating medium, and transformation was mediated by vector pCAMBIA1301, which contains a reporter gene -glucuronidase (GUS), a selectable marker gene, hpt, for hygromycin resistance and the genes of interest, acsA and acsB. The integration and expression of acsA, acsB and GUS in the genome of transgenic plants were analyzed with Southern blot hybridization, PCR, histochemical GUS assay and Northern blot hybridization. We found that following pollination on the cotton stigma transformed pollen retained its capability of double-fertilization and that normal cotton seeds were produced in the cotton ovary. Of 1,039 seeds from 312 bolls pollinated with transformed pollen grains, 17 were able to germinate and grow into seedlings for more than 3 weeks in a nutrient medium containing 50 mg/l hygromycin; eight of these were transgenic plants integrated with acsA and acsB, yielding a 0.77% transformation rate. Fiber strength and length from the most positive transformants was 15% greater than those of the control (non-transformed), a significant difference, as was cellulose content between the transformed and control plants. Our study suggests that transformation through vacuum infiltration and Agrobacterium mediated transformation can be an efficient way to introduce foreign genes into the cotton pollen grain and that cotton fiber quality can be improved with the incorporation of the prokaryotic genes acsA and acsB.Communicated by D. Bartels     

Variation in biological characteristics and esterase patterns among populations of Bemisia tabaci, and the association of one population with silverleaf symptom induction

Biological characteristics (oviposition and survival rates) and esterase banding patterns in native PAGE were investigated to evaluate variation among three populations of Bemisia tabaci Gennadius (Homoptera: Aleyrodidae). Reproductive capabilities of whiteflies from cotton (Gossypium hirsutum L.) and pumpkin (Cucurbita maxima Duchesne) populations were similar on the three host plant species tested. These populations, which had the same wild-type field origin, reproduced better on either cotton and pumpkin than on poinsettia (Euphorbia pulcherrima Willdenow). In contrast, poinsettia whiteflies exhibited relatively similar reproductive capabilities for the three host species tested. Pumpkin and cotton whiteflies had similar esterase banding patterns (A type), while poinsettia whiteflies yielded a different banding pattern (B type). In transmission studies, whiteflies from cotton or pumpkin sources did not induce silverleaf (SSL) or white stem (WS) symptoms in Cucurbita spp. tested. In contrast, poinsettia whiteflies were associated routinely with SSL and WS symptoms in Cucurbita spp. following colonization by whitefly adults. From these data, it was possible to correlate a specific esterase banding pattern (A or B) with reproductive capabilities and the ability to induce SSL and WS symptoms.     

Extraction and preliminary characterizaion of a mycobacteriolytic preparation (stazyme) from aStaphylococcus strain: mycobactericidal activity and its use in rapid extraction of mycobacterial DNA

The clear culture filtrate from 1-L culture of a laboratory contaminant ofStaphylococcus (coagulase^– strain, designated Clavelis) was filtered, concentrated, dialyzed, and the proteins were precipitated. The precipitate was washed, concentrated, and aliquoted (about 4 mg of total proteins/ml, designated as Stazyme). The crude preparation was subjected to gel filtration on Sephadex G-75, and the fractions were screened for their lytic ability againstMycobacterium smegmatis. Native proteins in the stazyme were electrophoretically separated, electroeluted, and their lytic activity againstM. smegmatis was compared with parallel controls (partially purified proteins extracted from the same quantity of the uninoculated bacterial growth medium). Only stazyme preparations caused significant growth inhibition ofM. smegmatis, M. chelonae, M. xenopi, M. tuberculosis, andM. kansasii. Stazyme essentially possessed a lytic activity measured with purifiedM. smegmatis andMicrococcus lysodeikticus cell walls and showed high bactericidal activity againstM. smegmatis, M. chelonae, andM. tuberculosis. It was also able to rapidly lyse intactM. smegmatis organisms, permitting significant yield of mycobacterial DNA.     

Novel effect of aromatic compounds on the iron-dependent expression of theEscherichia coli K12 manganese superoxide dismutase (sodA) gene

Summary InEscherichia coli, the superoxide dismutase genes (sodA andsodB) sense the availability of Fe through the action of thefur locus [E. C. Niederhoffer, C. M. Naranjo, K. L. Bradley, J. A. Fee (1990) Control ofEscherichia coli superoxide dismutases (sodA andsodB) genes by the ferric uptake regulation (fur) locus,J. Bacteriol. 172, 1930–1938]. Previous work from other laboratories has shown that a variety of metal chelators and of redox-active aromatic compounds can dramatically induce expression ofsodA. Here we show that non-redox-active, non-metal-chelating aromatic compounds also enhance expression of a chromosomalsodA gene fusion and that these effects are strongly modulated by the Fur phenotype (Fur^±) and by the availability of iron in the culture medium. The compounds studied were ethidium bromide, hemin, 2,2-bipyridine, 1,10-phenantroline, 4,7-phenantroline, rhodamine B1, rhodamine 6G, and, for comparison to previous studies, Paraquat.Abbreviations DTPA diethylenetriaminepentaacetic acid - Paraquat N,N-dimethyl-1,1-bipyridene - bpy 2,2-bipyridine - phen 1,10-phenanthroline - 4,7-phen 4,7-phenanthroline     

Some pathological studies in two species of Phytophthora

Summary The paper deals with some detailed pathological investigations with two species ofPhytophthora, viz.,Phytophthora palmivora andP. parasitica var.macrospora causing severe fruit rots ofAchras sapota andAnona squamosa respectively. Both the isolates were found pathogenic to a variety of fruits including papaya, tomato, chillis, banana, fig, apple, cucumber, guava, orange, onion bulb and potato tuber. They were, however, non-pathogenic to carrot, zinger, turmeric andColocasia corms. In the seedling inoculation experiment they showed pathogenic nature to castor bean, brinjal, cotton, sesamum, pea, French bean,Cactus sp. andBryophyllum leaves. It is interesting to note that only the Isolate S caused infection to the plants ofVinca rosea L., whereas the Isolate C failed to do so.This work frames up a part of Senior author's M.Sc. (Agri.) Thesis, approved by the University of Poona, India.Respectively, Ex-Junior Research Fellow (1958–60), Indian Council of Agricultural Research, New Delhi; Principal and Professor of Plant Pathology, College of Agriculture, Junagad, (Gujarat) and Mycologist, Wheat Rust Research Station, Mahabaleshwar (Satara Dist.) India.     

Relation of nitrogen fertilizers and manure to vascular wilt of egyptian cotton caused by four fusaria species and strains

Summary Four different species and strains ofFusarium, namely,F. oxysporum f.vasinfectum (Atk.)Snyder &Hansen,F. solani (Mart.)App. &Wr.,F. vasinfectum (Atk.) f₁ Wr. strainFahmy, andF. vasinfectum Atk. are responsible for cotton wilt in U.A.R. Pathogenicity experiments have shown that the four experimentalFusaria possess varying degrees of pathogenicity towards two susceptible cotton varieties, namely, Karnak and Bahtim 190. On the other hand, Ashmouni cotton proved resistant to the fourFusaria. Variability of pathogenicity of the experimentalFusaria is not only related to host cotton plant or parasite, but also to nitrogenous fertilizer or manurial treatment of the soil. Resistance of Ashmouni cotton was not broken in presence of sodium nitrate, ammonium nitrate or stable manure added to soil inoculated with any of the fourFusaria. The application of nitrogen fertilizers or manure resulted on the whole, in increased wilt-disease incidence of the susceptible cotton varieties. Stable manure enhanced predisposition to vascular-wilt more than other nitrogen treatments, especially in presence of the virulentF. oxysporum f.vasinfectum or both strains ofF. vasinfectum Atk. Ammonium nitrate induced the sudden appearance of mottling characteristic of vascular-wilt of cotton when Bahtim 190 plants were raised in nitrogen-fertilized soil inoculated withF. solani (Mart.)App. &Wr. At the same time, the raised affected plants showed increased growth-vigour and enhanced maturity of their leaves.     

Activity of dihydrofolate reductase in the mollicutesAcholeplasma laidlawii andMycoplasma gallisepticum and their susceptibility to antifolates

Mycoplasma gallisepticum andAcholeplasma laidlawii were found to possess dihydrofolate reductases exhibiting similar specific activities and kinetics, with values in the range of those reported for other microorganisms. The apparent Km values for dihydrofolate in enzymes ofM. gallisepticum andA. laidlawii are 7.95±0.13 and 7.50±0.11 M, and for NADPNH 8.46±0.25 and 9.32±0.18 M, respectively.M. gallisepticum is 3300-fold more resistant to methotrexate than isA. laidlawii; concentrations causing 50% inhibition were 200.00 and 0.06 M, respectively. This is in contrast to almost the same sensitivity to that drug exhibited by the dihydrofolate reductases of both microorganisms.M. gallisepticum is also 3600-fold more resistant to trimethoprim than isA. laidlawii, and the concentrations for 50% inhibition of growth were 1800.0 and 0.5 M, respectively. The high resistance was found to be due partially to a 130-fold lower affinity of the target enzyme for this antifolate, but another mechanism, presumably impaired transport, must also be involved. This is the first report of dihydrofolate reductase activity in Mollicutes.     

DNA polymorphisms in the ψβ1- and β-globin gene regions in asian macaques

DNA polymorphisms in the ₁--globin gene region in nine Asian macaques(Macaca fuscata, M. mulatta, M. nemestrina, M. cyclopis, M. fascicularis, M. arctoides, M. radiata, M. maura, andM. assamensis) were examined using several restriction endonucleases and the human ₁, IVS2, and IVS2 probes. TheBamHI site 3 to the -globin gene was polymorphic inM. fuscata andM. mulatta, while the HincII site and the EcoRI site in the ₁-globin gene region was highly polymorphic inM. fuscata andM. mulatta, respectively. These polymorphic sites also seem to be present in other Asian macaques. The present study of the polymorphism at theBamHI site 3 to the -globin gene in Asian macaques supports, at the nuclear DNA level, the idea that thefascicularis group includingM. fuscata, M. mulatta, M. cyclopis, andM. fascicularis is different from other Asian macaque groups.This study was supported in part by the Cooperation Research Program of the Primate Research Institute, Kyoto University.     

Inhibition by excitatory sulphur amino acids of the high-affinityl-glutamate transporter in synaptosomes and in primary cultures of cortical astrocytes and cerebellar neurons

A detailed kinetic study of the inhibitory effects ofl- andd-enantiomers of cysteate, cysteine sulphinate, homocysteine sulphinate, homocysteate, and S-sulpho-cysteine on the neuronal, astroglial and synaptosomal high-affinity glutamate transport system was undertaken.d-[³H] Aspartate was used as the transport substrate. Kinetic characterisation of uptake in the absence of sulphur compounds confirmed the high-affinity nature of the transport systems, the Michaelis constant (K _m) ford-aspartate uptake being 6 M, 21 M and 84 M, respectively, in rat brain cortical synaptosomes and primary cultures of mouse cerebellar granule cells and cortical astrocytes. In those cases where significant effects could be demonstrated, the nature of the inhibition was competitive irrespective of the neuronal versus glial systems. The rank order of inhibition was essentially similar in synaptosomes, neurons and astrocytes. Potent inhibition (K _iK _m) of transport in each system was exhibited byl-cysteate, andl- andd-cysteine sulphinate whereas substantially weaker inhibitory effects (K _i>10–1000 times the appropriateK _m value) were exhibited by the remaining sulphur amino acids. In general, inhibition: (i) was markedly stereospecific in favor of thel-enantiomers (except for cysteine sulphinate) and (ii) was found to decrease with increasing chain length. Computer-assisted molecular modelling studies, in which volume contour maps of the sulphur compounds were superimposed on those ofd-aspartate andl-glutamate, demonstrated an order of inhibitory potency which was, qualitatively, in agreement with that obtained quantitatively by in vitro kinetic studies.Special issue dedicated to Dr. Elling Kvamme     

Sur l'état actuel des dermatophytes en Roumanie

Summary The actual state of dermatophytes in Romania is briefly reviewed. From the 20 species discovered, up to now, 14 belonged to the group of human and animal origin, the other 6 to geophilic dermatophytes.The most frequently isolated wereT. mentagrophytes, (var.interdigitale),M. audouinii, T. violaceum andT. rubrum, which altogether caused more than 50 % of the human ringworm found in the last 15 years.WhileT. mentagrophytes still remains the agent no. 1 of tinea pedis in Romania andT. rubrum keeps the first place in the nail involvements by dermatophytes, the first organism of tinea capitis areM. audouinii andT. violaceum, the former causing mainly the epidemic foci. Such epidemics may also be due toT. ferrugineum. The number of cases byT. schönleinii is more and more reduced. The infections byT. verruccosum are increasing. The rarity of cases due toT. gallinae, toT. equinum and toT. mengninii are pointed out.From the so called geophilic dermatophytes,M. gypseum, K. ajelloi andChrysosporium keratinophilum are mostly isolated from the Romanian soil.T. terrestre, T. evolceanui, T. indicum andM. cookei are infrequently found. A few isolates ofT. mentagrophytes andT. quinckeanum were also discovered in the soil.     

Ecophysiological aspects of growth and nitrogen fixation inAzospirillum spp.

The nitrogenase activity ofAzospirillum spp. is efficiently regulated by environmental factors. InA. brasilense andA. lipoferum a rapid switch off of nitrogenase activity occurs after the addition of ammonium chloride. As in photosynthetic bacteria, a covalent modification of nitrogenase reductase (Fe-protein) is involved. InA. amazonense, a non-covalent mechanism causes only a partial inhibition of nitrogenase activity after ammonium chloride is added. In anaerobic conditions, nitrogenase reductase is also switched off by a covalent modification inA. brasilense andA. lipoferum. Short-time exposure ofAzospirillum to increased oxygen levels causes a partially reversible inhibition of nitrogenase activity, but no covalent modification is involved.Azospirillum spp. show variations in their oxygen tolerance. High levels of carotenoids confer a slightly improved oxygen tolerance. Certain amino acids (e. g. glutamate, aspartate, histidine and serine) affect growth and nitrogen fixation differently inAzospirillum spp. Amino acids may influence growth and nitrogen fixation ofAzospirillum in the association with plants.Azospirillum brasilense andA. halopraeferens are the more osmotolerant species. They utilize most amino acids poorly and accumulate glycine betaine, which also occurs in osmotically stressed grasses as a compatible solute to counteract osmotic stress. Nitrogen fixation is stimulated by glycine betaine and choline. Efficient iron acquisition is a prerequisite for competitive and aerotoleran growth and for high nitrogenase activity.Azospirillum halopraeferens andA. amazonense assimilate iron reasonably well, whereas growth of someA. brasilense andA. lipoferum strains is severely inhibited by iron limitation and by competition with foreign microbial iron chelators. However, growth of certain iron-limitedA. brasilense strains is stimulated by the phytosiderophore mugineic acid. Thus, various plant-derived substances may stimulate growth and nitrogen fixation ofAzospirillum.     

The uptake of serotonin and dopamine by homogenates of frozen rat and human brain tissue

A recently described procedure of freezing and thawing, which allows retention of metabolic and functional integrity, has been applied in the study of serotonin and dopamine uptake into frozen rat and post mortem human frozen tissue. TheK _m andV _max for the serotonin uptake into human hypothalamus were estimated to be 0.12 M and 0.03 nmol/g/min respectively. TheK _m andV _max for the dopamine uptake into human putamen were estimated to be 0.28 M and 0.13 nmol/g/min respectively. The results indicate that the freezing procedure does not affect the uptake sites for these transmitters. The storage time before freezing is however of importance for theV _max value. TheK _m value for the uptake, on the other hand, seems to be rather resistant to storage time before freezing.     

A comparison of the fine structure ofMicrococcus diversus,Neisseria catarrhalis andNeisseria sicca

Examination of thin sections ofMicrococcus diversus, Neisseria catarrhalis andN. sicca reveals a cytoplasmic membrane, nuclear region and ribosomes which correspond to those recognized in other bacteria. Their cell walls are multilayered and resemble those of gram-negative microorganisms. Structures suggestive of mesosomes were observed inM. diversus andN. catarrhalis. These cytological observations concur with the findings of Kocur for the fine structure ofMicrococcus denitrificans andM. halodenitrificans. The taxonomic position of the problematic species in the genusMicrococcus is discussed.This study was supported by a grant from United States Department of Agriculture (USDA) Forest Service 4000, Grant 1.     

A submicroscopical study of leaves of alfalfa,Basil, and tobacco experimentally infected with lucerne mosaic virus

Summary The leaves of three species of plants (Medicago sativa L.,Ocymum basilicum L., andNicotiana tabacum L., cv.Samsun), previously infected with lucerne mosaic virus (LMV), were studied in the electron microscope. In the leaves ofM. sativa andO. basilicum the infection was systemic, while in the leaves ofN. tabacum the infection was local. In all the three species LMV particles were always detected only in the cytoplasm. Apart from the presence of virus particles in the cytoplasm, no ultrastructural alterations were found inM. sativa andN. tabacum. InO. basilicum, the green leaf areas did not show any prominent alterations, while the yellow leaf areas showed marked alterations of the chloroplasts. In these, the lamellar system was scarcely developed, and the few thylakoids tended to fragment, curl and disappear. In the chloroplast stroma, there was an abnormal development of filamentous structures, resembling the stromacentre.Publication n. 53 of Centro Nazionale Virus Vegetali, Consiglio Nazionale delle Ricerche, sections I and II.     

Effect of lime additions to acid strip-mine spoil on survival,growth and nitrogen fixation (acetylene reduction) of several woody legume and actinomycete-nodulated species

Summary An acid mine spoil in Southern Indiana was amended with lime (CaCO₃) (0.0, 12.5, 25 and 39t/ha) and planted withElaegnus umbellata Thunb.,Alnus glutinosa Gaertn.,Robinia pseudoacacia L.,Robinia fertilis Ashe, Arnot,Myrica pensylvania Lois,Caragana arborescens L. andShepherdia argentea Nutt. Survival and soil data were collected periodically and plants were harvested 15 months after planting. Nodule and top dry weights were determined and acetylene reduction assays performed on the nodules.Addition of lime caused significant increases in pH, and 39 t/ha of lime were required to maintain a pH above 5.5. Survival of plant material was greatest at the highest lime addition, although response of individual species varied.Elaeagnus umbellata, R. pseudoacacia, R. fertilis Arnot, andA. glutinosa appeared more tolerant of the harsh conditions. OnlyC. arborescens showed a linear increase in top dry weight due to lime addition.Alnus glutinosa andS. argentea achieved statistically the same growth regardless of pH, andR. fertilis Arnot andE. umbellata did not increase in top dry weight above an addition of 25 t/ha.Robinia pseudoacacia achieved maximum top dry weight at 25 t/ha, whereasM. pensylvanica growth declined with increasing pH. Nodule dry weights increased with increasing pH; however,S. argentea showed greater nodule dry weights at lower lime levels. Acetylene reduction rates increased with lime addition.Elaegnus umbellata did not respond above 25 t/ha lime, whereasA. glutinosa did not show an increase until this point.     

Purification and properties of extracellularβ-fructofuranosidases fromAureobasidium sp. ATCC 20524

Summary Two extracellular -fructofuranosidases (E-1 andE-2) fromAureobasidium sp. ATCC 20524, producing 1-kestose (1^F--fructofuranosyl-sucrose) from sucrose, were purified to homogeneity. Molecular weights of the enzymes were estimated to be about 304000 (E-1) and 315000 (E-2) Da by gel filtration. The enzymes contained 33% (w/w) (E-1) and 27% (w/w) (E-2) carbohydrate. TheK _m values for sucrose ofE-1 andE-2 andE-2 were 0.34 and 0.28 M, respectively. were 0.34 and 0.28 M, respectively. The enzymatic profiles of these enzymes were almost identical to intracellular enzymesP-1 andP-2 except for the differences in carbohydrate content andK _m values ofE-2 andP-2.     

Developmental times and oviposition rates of predatory mitesTyphlodromus pyri andAmblyseius andersoni (Acari: Phytoseiidae) reared on different foods

The developmental times and the reproduction of two resistant Italian strains ofTyphlodromus pyri Scheuten andAmblyseius andersoni (Chant) were studied in the laboratory by rearing them on the spider mitesPanonychus ulmi (Koch) andEotetranychus carpini (Oud.), on the eriophyidColomerus vitis (Pgst.) and on pollen ofMesembryanthemum criniflorum. The response ofT. pyri andA. andersoni females to a spider mite supply (P. ulmi orE. carpini) of 4, 8 and 16 adult female prey per female predator per day was also studied.Development ofT. pyri onE. carpini andC. vitis required a shorter period than onM. criniflorum pollen, while intermediate values were recorded forP. ulmi. When the highest number of prey was offered, the influence of different foods on oviposition rates ofT. pyri was not significant. An increase in spider mite supply favoured a shorter pre-oviposition period and higher oviposition rates.Development ofA. andersoni was faster on pollen than on spider mites, while intermediate values were found concerningC. vitis. Differences statistically significant were recorded for development onP. ulmi andC. vitis. Colomerus vitis proved to be the more suitable food in terms of oviposition. The oviposition rate decreased when feeding uponP. ulmi, but reached intermediate values onE. carpini andM. criniflorum. Increasing spider mite densities caused shorter pre-oviposition times and higher oviposition rates. Using a given number ofE. carpini females, rather than those ofP. ulmi, resulted in higher oviposition rates and shorter pre-oviposition times.For both predators, the results suggest a higher intrinsic rate of population increase onE. carpini orC. vitis than onP. ulmi.The research was supported by a grant from Regione Veneto (Lotta biologica ed integrata nel controllo di insetti ed acari dannosi).The general lines of the research have been planned by C. Duso. The authors contributed equally to the experimental work.     

Time- and dose-dependent effects of protein kinase C on proximal bicarbonate transport

Summary Activation of protein kinase C has been shown to cause both stimulation and inhibition of transport processes in the brush-border membrane and renal tubule. This study was designed to examine the dose-response nature and time-dependent effect of 4 -phorbol-12-myristate-13-acetate (PMA) on the rates of bicarbonate absorption (J _HCO3) and fluid absorption (J _v) in the proximal convoluted tubule (PCT) of rat kidney. Bicarbonate flux was determined by total CO₂ changes between the collected fluid and the original perfusate as analyzed by microcalorimetry. Luminal perfusion of PMA (10^–10 10^–5 M) within 10 min caused a significant increase ofJ _HCO3 andJ _v. A peaked curve of the dose response was observed with maximal effect at 10^–8 M PMA on both bicarbonate and fluid reabsorption, which could be blocked completely by amiloride (10^–3 m) and EIPA (10^–5 M). On the other hand, with an increase of perfusion time beyond 15 min, PMA (10^–8 and 10^–6 M) could inhibitJ _HCO3 andJ _v. Amiloride (10^–3 M) or EIPA (10^–5 M) significantly inhibitsJ _HCO3 andJ _v, while there is no additive effect of PMA and amiloride or EIPA on PCT transport. An inactive phorbol-ester, 4-phorbol, that does not activate protein kinase C, had no effects onJ _HCO3 andJ _v. Capillary perfusion of PMA (10^–8 M) significantly stimulate bothJ _HCO3 andJ _v; however, PMA did not affect glucose transport from either the luminal side or basolateral side of the PCT. These results indicate that activation of endogenous protein kinase C by PMA could either stimulate or inhibit both bicarbonate and fluid reabsorption in the PCT dependent on time and dose, and these effects are through the modulation of Na⁺/H^– exchange mechanism.     

Somatic embryogenesis and plant regeneration of pepper in liquid media

A protocol was developed for regeneration of pepper (Capsicum annuum var. Ace) through somatic embryogenesis in liquid media. For embryogenic callus formation, mature zygotic embryo explants were used on basal Murashige and Skoog medium with 9.05 M 2,4-dichlorophenoxyacetic acid and 3% sucrose. Embryogenic callus was transferred to liquid basal Murashige and Skoog medium with 4.52 M 2,4-dichlorophenoxyacetic acid and 3% sucrose in order to increase the mass of the embryogenic culture. After pretreatment with potassium citrate, cells were placed into embryo initiation medium with 6 g l^-1 l-proline and a decreased (10 mM) ammonium concentration. Embryos were matured in 1.89 M abscisic acid containing half-strength Murashige and Skoog medium and converted into plants bothin vivo andin vitro at up to a 97% efficiency.     

Antagonism between Rhizoctonia solani causing damping — off and selected rhizospheric microflora of some egyptian cotton varieties

Summary Seven bacterial isolates and many species of fungi have been isolated from the rhizospheres of Ashmouni and Karnak cotton variety seedlings. Two strains ofBacillus subtilis and two fungi, namelyAspergillus terreus andAspergillus flavus proved to be antagonistic toRhizoctonia solani on glucose — peptone agar. Other antagonistic bacterial isolates were slow growers on the agar medium, and hence were not chosen for further studies. Similarly, most of the other rhizospheric fungi of cotton were of the compatible type and were, therefore, rejected.