Studies on the rhizosphere mycoflora of broad bean and cotton

Summary The fungal flora of the rhizosphere of three varieties of broad bean and cotton was studied by the dilution-plate technique. The numbers of fungi were higher in the rhizosphere than in the non-rhizosphere soil. Plant type and age, and soil type have a significant influence of the nature and numbers of fungal flora associated with plant roots.Cladosporium was relatively more abundant in the rhizosphere of broad bean varieties, whilePenicillium was found to constitute a high percentage of fungi found in the rhizosphere of cotton varieties. Plant variety has no influence on the nature of such fungal flora.     

Studies on the rhizosphere mycoflora of broad bean and cotton

Summary Seed and root exudates from three varieties of both broad bean and cotton grown aseptically were analyzed for amino acids and sugars. Broad bean varieties were found to excrete considerable amounts of amino compounds with 15 different amino acids, while cotton varieties excreted less consisting of 12 amino acids. Five sugars were identified in the seed and root exudates from broad bean varieties, while three were present in the seed and root exudates from cotton varieties. Seed and root exudates stimulated spore germination and growth of fungi isolated from the rhizosphere.     

Studies on the rhizosphere mycoflora of broad bean and cotton

Investigations were made on the effect of species of fungi isolated from therhizosphere of broad bean (Vicia faba Linn.) variety Giza I, and cotton (Gossypium barbadense Linn.) variety Giza 47, on plant growth. Broad bean rhizosphere fungi differently affected plant growth.Fusarium moniliforme, Penicillium martensii, Rhizopus stolonifer, andCladosporium sphaerospermum stimulated both root and shoot growth.Aspergillus niger andAlternaria tenuis have an inhibitory effect on plant growth. On the other hand, the rhizosphere fungi of cotton namely,Penicillium cyclopium, Aspergillus terreus, Cephalosporium sp.,Aspergillus niger, Cladosporium sphaerospermum, andFusarium oxysporum stimulated plant growth.     

The phytotoxic effect of exogenous ethanol on Euphorbia heterophylla L.

This study investigated the effects of exogenously applied ethanol on Euphorbia heterophylla L., a troublesome weed in field and plantation crops. Ethanol at concentrations ranging from 0.25 to 1.5% caused a dose-dependent inhibition of germination and growth of E. heterophylla. Measurements of respiratory activity and alcohol dehydrogenase (E.C. 1.1.1.1) activity during seed imbibition and initial seedling growth revealed that ethanol induces a prolongation of hypoxic conditions in the growing tissues. In isolated mitochondria, ethanol inhibited the respiration coupled to ADP phosphorylation, an action that probably contributed to modifications observed in the respiratory activity of embryos. A comparison of the effects of methanol, ethanol, propanol and acetaldehyde on germination and growth of E. heterophylla indicates that alcohol dehydrogenase activity is required for the observed effects, with the conversion of ethanol to acetaldehyde playing a role in the ethanol-induced injuries.     

Chromosome number and cytogenetics of Euphorbia heterophylla L

Euphorbia heterophylla L. (Euphorbiaceae) is a herbaceous species of great economic importance due to its invasive potential and consequent damage to agriculture and pasture land. For the first time, we provide information on its chromosome number, morphology, and behavior of mitotic chromosomes. Seeds were germinated and submitted to four treatments to obtain metaphases: 0.5% colchicine for 2 to 5 h, at ambient temperature; 0.5% colchicine for 16 to 24 h; 0.0029 M 8-hydroxyquinoline (8-HQ) for 2 to 5 h at ambient temperature, and 0.0029 M 8-HQ for 16 to 24 h at 4 degrees C. The material was then fixed in methanol:acetic acid (3:1) and kept at -20 degrees C for 24 h. Roots were macerated in the enzyme solution of Flaxzyme (NOVO FERMENT)-distilled water (1:40) at 34 degrees C for 2 h and later fixed again. Chromosome preparations were obtained by the dissociation of the apical meristems. The best chromosome preparations were obtained with the use of 8-HQ for 21 h 30 min at 4 degrees C. E. heterophylla showed 2n = 28 chromosomes. The short arm of the largest pair of chromosomes of the complement (pair number 1) displayed a secondary constriction while the nucleolus was observed in the interphasic cell. Structural rearrangements were also observed in the E. heterophylla L. genome. The genomic instability associated with polyploidy may be the result of selection shaped by environmental adaptations and/or human-induced manipulation through agricultural practices.     

Accumulation of non-utilizable starch in laticifers of Euphorbia heterophylla and E. myrsinites

Starch biosynthesis and degradation was studied in seedlings and mature plants of Euphorbia heterophylla L. and E. myrsinites L. Mature embryos, which lack starch grains in the non-articulated laticifers, develop into seedlings that accumulate starch rapidly when grown either in the light or the dark. Starch accumulation in laticifers of dark-grown seedlings was ca. 47 and 43% of total starch in light-grown controls in E. heterophylla and E. myrsinites, respectively. In light-grown seedlings, starch was present in laticifers as well as parenchyma of stems and leaves, whereas in dark-grown seedlings starch synthesis was almost exclusively limited to laticifers. In 7-month-old plants placed into total darkness, the starch in chyma was depleted within 6 d, whereas starch in laticifers was not mobilized. The starch content of latex in plants during development of floral primordia, flowering, and subsequent fruit formation remained rather constant. The results indicate that laticifers in seedlings divert embryonal storage reserves to synthesize starch even under stress conditions (darkness) in contrast to other cells, and that starch accumulated in laticifers does not serve as a metabolic reserve. The laticifer in Euphorbia functions in the accumulation and storage of secondary metabolites yet retains the capacity to produce, but not utilize starch, a primary metabolite.     

Studies on the rhizosphere mycoflora of broad bean and cotton. Effect of fungal filtrate on plant growth

The dominating rhizosphere fungi of broad bean (Vicia faba Linn.) variety “Giza 1”, and cotton (Gossypium barbadense Linn.) variety “Giza 47”, were grown in liquid medium. After 10 days, filtrates were obtained and sterilized by filtration through sintered-glass filter. Plants were grown in sterile sand which was supplemented with nutrient solution. Every plant was irrigated with fungal filtrate, unconsumed medium, and water. The filtrates of the rhizosphere fungi of both broad bean and cotton stimulated plant growth.     

Effect of soil amendement with root extract ofhibiscus cannabinus L. on its rhizosphere mycoflora

Summary Rhizosphere mycoflora ofH. cannabinus was studied in potted condition after its root extract obtained from two month old plants. Isolations of fungi from the root regions were done at the interval of 15 days by dilution plate method. Estimation of fungi/g dry soil showed a negative rhizosphere effect. A higher number of fungal species was recorded in the treated non-rhizosphere as compared to their number in the rhizosphere. Qalitative analysis of the fungal flora was done and the variation was recorded. Root extract was analysed by paper chromatography. Altogether 7 amino acids and 3 sugars were detected.     

Chemical Characterization of Euphorbia heterophylla L. Essential Oils and Their Antioxidant Activity and Allelopathic Potential on Cenchrus echinatus L.

The genus Euphorbia attracted the attention of many researchers worldwide from natural products, bioactivity, and ecological perspective. The essential oils (EOs) of Euphorbia heterophylla are poorly studied. Therefore, the present study aimed to provide a detailed profile of the E. heterophylla EOs as well as to determine their antioxidant and allelopathic activities. The EOs from aerial parts of E. heterophylla were extracted using hydrodistillation and analyzed via GC/MS. The antioxidant activity was determined based on scavenging of the free radical, 1,1‐diphenyl‐2‐picrylhydrazyl and H₂O₂. Various concentrations of the EOs were tested against the noxious weed, Cenchrus echinatus. Thirty‐five compounds were identified representing 100 % of the total mass. Four classes of components were characterized, among which terpenoids were the main components (88.70 %). Monoterpenes represented the main class (69.48 %), followed by sesquiterpenes (18.63 %), and only one diterpenoid, kaur‐16‐ene, was identified. 1,8‐Cineole (32.03 %), camphor (16.54 %), β‐elemene (5.92 %), endo‐borneol (4.94 %), limonene (4.27 %), pentatriacontane (3.91 %), and α‐pinene (3.89 %) were the major compounds. The EOs composition of Egyptian E. heterophylla ecospecies was comparable to that of other reported Euphorbia species, although it showed no correlation with Nigerian E. heterophylla ecospecies. The EOs from E. heterophylla aerial parts exhibited significant antioxidant activity. Moreover, a concentration of 100 μL L^?1 of the EOs reduced the germination, root, and shoot growth of C. echinatus by about 93.95 %, 84.6 %, and 57.8 %, respectively. Therefore, the EOs from E. heterophylla could be integrated into the control of this weed, as eco‐friendly biocontrol method. Further study is needed to characterize their allelopathic activity under field conditions as well as to evaluate their durability and biosafety.     

Multiple forms of endo-1,4-beta-glucanases in the endosperm of Euphorbia heterophylla L

Germinating seeds of Euphorbia heterophylla L. contain endo-1,4-beta-glucanases which degrade carboxymethylcellulose (CMC). The activity decreased approximately 66% in extracts of endosperm containing isopropanol or ethanol. The endoglucanases were isolated from endosperm extracts using ammonium sulphate fractionation followed by Sephacryl S-100-HR chromatography resulting in two main peaks: I and II. Peak I endoglucanase was further purified about 15-fold on DEAE-Sephadex A50 and then by affinity chromatography (CF11-cellulose). Peak II endoglucanases were further purified 10-fold on CM-cellulose chromatography. The results indicated the occurrence of a 66 kDa endoglucanase (fractionated by SDS-PAGE and visualized by activity staining using Congo Red). Several acidic (pI 3.0 to 5.7) and basic (pI 8.5 to 10.0) forms from both peaks which differed in their capacities for degrading CMC or xyloglucans from Copaifera langsdorffii or Hymenaea courbaril were detected.     

Fungal pathogens of Euphorbia heterophylla and E. hirta in Brazil and their potential as weed biocontrol agents

A two-year survey of the fungi associated with two important congeneric pantropical weeds, Euphorbia heterophylla and E. hirta, was conducted in part of their native range in southern Brazil. Sampling was concentrated mainly in Rio de Janeiro State and ten species were identified as pathogens of these weeds. Two taxa, Botrytis ricini and Uromyces euphorbiae, were common to both weed hosts. Alternaria euphorbiicola, Bipolaris euphorbiae, Melampsora sp., Oidium sp. and Sphaceloma poinsettiae were recorded only from E. heterophylla, whereas Colletotrichum gloeosporioides, Sphaceloma sp. and Sphaerotheca fuliginea were restricted to E. hirta. Botrytis ricini and Colletotrichum gloeosporioides are new records for E. hirta, and Alternaria euphorbiicola and Sphaerotheca fuliginea are new host records for Brazil. Bipolaris euphorbiae, previously identified as Helminthosporium sp., is considered to be the correct name for the causal agent of a major disease of E. heterophyllum in Brazil. The potential of these pathogens as biocontrol agents is discussed and the mycobiota associated with both these weeds worldwide is reviewed.This revised version was published online in October 2005 with corrections to the Cover Date.     

Effect of virus infection on the rhizosphere mycoflora of papaya plants

Summary Rhizosphere mycoflora of PLRV (Papaya Leaf Reduction Virus)- infected and healthy papaya plants have been investigated at the pre-flowring, flowering and post-flowering stages of plants. The fungal population per g of soil was higher in rhizosphere of diseased plants at all the three stages than that of healthy ones. The increased C/N ratio in the leaves of PLRV-infected papaya plants is responsible for the increased rhizosphere mycoflora concentration of infected plants.     

泽漆化学成分及其体外抗肿瘤活性研究

利用正相硅胶柱层析、葡聚糖凝胶Sephadex LH-20、制备薄层层析、反相制备色谱等离手段和1H、13C NMR等波谱技术,从泽漆(Euphorbia helioscopia L.)中分离鉴定了10个化合物,分别为β-谷甾醇(β-sitosterol,1),大戟甘(euphornin,2),大戟甘D(euphomin D,3),A(euphohelioscopin A,4),槲皮素(quercetin,5),没食子酸(gallic acid,6),咖啡酸(caffeie acid,7),没食子酸乙酯(ethyl gallate,8),杨梅素(myrecetin,9),金丝桃苷(hypero-side,10),其中化合物7、8、9是首次从该植物中分得,通过体外抗肿瘤活性研究,化合物6和10作为泽漆的抗肿瘤活性成分属首次报道.     

Isolation and partial characterization of a lectin from Euphorbia heterophylla seeds.

An N-acetylgalactosamine-specific lectin was isolated from Euphorbia heterophylla seeds by affinity chromatography on cross-linked arabinogalactan. It is a dimeric protein of two identical subunits of Mr 32 000, and differs structurally from all previously known Euphorbiaceae lectins. Its distribution over the seed is typical in that it is merely confined to the primary axes.     

Effect of certain chemical fertilizers on the rhizosphere mycoflora ofOryza sativa linn

The present paper deals with the study of the effect of potassium fertilizer (Potassium sulphate) on rhizosphere mycoflora ofOryza sativa. The fertilization improves the microbial activity both in rhizosphere and nonrhizosphere regions. 40 lbs/acre dose of the fertilizer proved best for paddy growth and rhizosphere fungal poulation. The highest fungal population was recorded at the time of flowering of the plants.     

Foliar spray of gibberellic acid and its influence on the rhizosphere and rhizoplane mycoflora

Summary The effect of foliar spray of Gibberellic acid in different concentrations was studied. The variation in the number of fungi/g of dry soil in rhizosphere was found to be significant in case ofD. alba andO. sanctum and insignificant in case ofW. somnifera. Qualitatively, no marked difference was observed in the rhizosphere fungal flora of sprayed and control plants.     

α-Naphthalene Acetic Acid Regulated Anthocyanins,Polyphenols and Associated Enzymes in Euphorbia heterophylla L. Seedling Explant Cultures

Stem and leaf explants of Euphorbia heterophylla L. were cultured on Murashige and Skoog’s medium (MSM) supplemented with α-naphthalene acetic acid (NAA) at different concentrations. Fresh weight of callus from both the explants increased by augmenting NAA. However, rhizogenesis decreased as measured by the fresh weight of root mass. Anthocyanin and polyphenol accumulation, activities of phenylalanine ammonia lyase, peroxidase and polyphenol oxidase decreased with elevated NAA concentration. Plantlet regeneration occurred in the absence of exogenous cytokinins. Possibility of replacing hazardous synthetic food colourants by anthocyanins produced in vitro is suggested.     

Effect of foliar spray of hormones on the rhizosphere mycoflora of leguminous weeds

Summary The effect of the foliar spray of two hormonesviz indole acetic acid and gibberellic acid on the rhizosphere mycoflora ofCassia tora L. andCrotalaria medicaginea Lamk., two leguminous weeds, has been studied at different stages of growth of the plants. Three sprays of the aqueous solutions of the hormones were made from the seedling stage onwards and, in all, five samplings of the rhizospheres were made. Estimation of the mycoflora was made by the dilution plate method as described in the text, using dextrose-peptone-agar-rose bengal medium. Statistically significant increase in the total number of fungi was observed in the rhizosphere of sprayed plants. With regard to the total number of species, there was no significant difference between the treated and control plants. It has been concluded that the stimulation of the rhizosphere mycoflora on foliar application of hormones might be due to the enhanced sporulation of fungi in the rhizosphere effected by the exudation of stimulatory factors from the roots.Part of doctoral thesis, Banaras Hindu University (1966).     

Effect of certain chemical fertilizers on the rhizosphere mycoflora of Oryza sativa Linn

Summing up, it may be concluded that Superphosphate fertilization stimulated the fungal flora both in rhizosphere and corresponding nonrhizosphere regions and a few selected fungal species were preferentially stimulated at different stages of the plant growth.Department of Botany, Banaras Hindu University, Varanasi-5 (India).