Influence of arbuscular mycorrhizae on the metabolism of maize under drought stress

A greenhouse experiment was carried out to investigate the influence of the arbuscular mycorrhizal (AM) fungus (Glomus intraradices Schenck & Smith) on metabolic changes in tropical maize (Zea mays L.) under drought. Two cultivars, Tuxpeno sequia CO (drought sensitive) and C8 (drought resistant), were subjected for 3 weeks to water stress following tasselling (75–95 days after sowing). Fully expanded 7th or 8th leaves were sampled and assessed for levels of chlorophyll, sugars, proteins, and amino acids. Chlorophyll content was not altered either by water stress or the presence of mycorrhizae. Mycorrhizal plants (M+) had higher total and reducing sugars than nonmycorrhizal plants (M-) at the end of 3 weeks of the drought cycle. An increase in protein content was observed with drought stress in M + plants of the cultivar C0. Most of the amino acids showed a linear increase during the period of water stress in M+ and M- plants for both cultivars. Total amino acids increased by 40.6% and 43.7% in M- plants of C0 and C8, respectively. With the presence of AM fungus, amino acid levels increased by only 10.7% and 19.2% of leaf dry mass in C0 and C8, respectively. Alanine, asparagine, glutamine, and glycine accounted for 70% of the amino acid pool. Under drought, AM inoculation enabled the plants to retain considerable amounts of sugars and proteins, especially in the drought-sensitive cultivar C0. This may be of physiological importance in helping the plant to withstand moderate drought.     

Effect of temperature on pseudo-self-compatibility in Trifolium pratense L.

Summary A relatively high temperature treatment, applied during anthesis, was shown to enhance self-seed production through pseudo-self-compatibility in normally self-incompatible red clover (Trifolium pratense L.). The self-seeds were produced in cultures of excised stems held in 2.5 percent sucrose. The stems were excised when petal color was beginning to appear in the buds. During anthesis the cultures were incubated with the flower heads at 40 ° and the stems at 25 °C. When most of the florets per head had opened the cultures were transferred to 20 °C and held at that temperature during the period of pollen growth through the styles and also during seed development. The addition of calcium nitrate and boric acid to the culture medium did not enhance anthesis, seed weight, or the number of seeds produced.Plant genotype and the environment provided before anthesis were the primary factors influencing the number of self-seed produced. Although not all attempts to produce self-seed have been successful, with repeated trials all clones we tested produced some seed.

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Zusammenfassung Durch eine Behandlung normalerweise selbstunverträglichen Rotklees (Trifolium pratense L.) mit verhältnismäßig hohen Temperaturen während der Anthesis ergab sich eine Erhöhung des Samenertrages durch Pseudo-Selbstverträglichkeit. Die Samen aus der Selbstbefruchtung wurden an Kulturen abgeschnittener Stengel erzielt, die in 2.5% Sucrose gehalten wurden. Die Stengel waren zu dem Zeitpunkt, an dem die Petalenfarbe in den Knospen sichtbar wurde, abgeschnitten worden. In einem Brutraum wurden die Blütenköpfe während der Anthesis bei 40 °C und die Stengel durch Eintauchen der Kulturgläser in ein Wasserbad bei 25 °C gehalten. Sobald sich die Mehrzahl der Blütchen geöffnet hatte, wurden die Kulturen in 20 °C übergeführt und in dieser Temperatur während des Pollenwachstums durch die Griffel und auch während der Samenentwicklung belassen. Eine Beigabe von Kalziumnitrat und Borsäure zum Kulturmedium steigerte weder die Anthesis noch das Samengewicht und die Anzahl der erzeugten Samen. Der Genotyp der Pflanze und die Umwelt vor der Anthesis waren die Primärfaktoren, die die Anzahl der Samen aus Selbstbefruchtung beeinflußten. Obwohl nicht alle Versuche, Samen aus Selbstbefruchtung zu erzielen, erfolgreich waren, erzeugten in wiederholten Versuchen doch alle untersuchten Klone etwas Samen.

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Cooperative research by Crops Research Division, Agricultural Research Service, U.S. Department of Agriculture and the Kentucky Agricultural Experiment Station. This paper (No. 68-3-102) is published with permission of the Director, Kentucky Agricultural Experiment Station.     

Plant regeneration from hypocotyl and petiole callus of Trifolium pratense L.

Red clover (Trifolium pratense L.) seedlings were screened for the ability to regenerate plantlets from hypocotyl-derived callus tissue. Media sequences described by Beach and Smith (1979) and Collins and Phillips (1982) and a variation using media from both sequences were tested. Plantlets were regenerated from three out of 642 genotypes. In all three cases, callus was initiated on B5C medium and regeneration was accomplished on SPL medium. Attempts to regenerate plants from petiole-derived callus tissue have so far been successful only with regenerants of clone F49. Petiole callus from epicotyl-derived F49 plants proved to be non-regenerative. Pollen viability varied significantly among individuals regenerated from callus cultures of clone F49. Root tip squashes from F49 regenerants revealed the normal diploid chromosome number (2n=14). The frequency of regeneration within progeny from reciprocal crosses between F49 regenerants and several non-regenerative genotypes was 29%.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - BAP benzylaminopurine - KN kinetin - NAA -naphthaleneacetic acid     

Influence of arbuscular mycorrhizal mycelial exudates on soil bacterial growth and community structure

Plant root systems colonized by arbuscular mycorrhizal (AM) fungi have previously been shown to influence soil bacterial populations; however, the direct influence of the AM extraradical mycelium itself on bacterial growth and community composition is not well understood. In this study, we investigated the effects of exudates produced by AM extraradical mycelia on the growth and development of an extracted soil bacterial community in vitro. The chemical composition of the mycelial exudates was analysed using proton nuclear magnetic resonance spectrometry. Following the addition of exudates to a bacterial community extracted from soil, bacterial growth and vitality were determined using a bacterial vitality stain and fluorescence microscopy. Changes in community composition were also analysed at various times over the course of 3 days by terminal restriction fragment length polymorphism analysis, in combination with cloning and sequencing of 16S rRNA genes. Mycelial exudates increased bacterial growth and vitality and changed bacterial community composition. Several Gammaproteobacteria, including a taxon within the Enterobacteriaceae, increased in frequency of occurrence in response to AM mycelial exudates. This study is the first attempt to identify carbohydrates from the extraradical mycelium of an AM fungus, and demonstrates the direct effects of mycelial exudates on a soil bacterial community.     

Influence of the zinc hyperaccumulator Thlaspi caerulescens J. & C. Presl. and the nonmetal accumulator Trifolium pratense L. on soil microbial populations

Metal hyperaccumulator plants like Thlaspi caerulescens J. & C. Presl. are used for phytoremediation of contaminated soils. Since little is known about the rhizosphere of hyperaccumulators, the influence of T. caerulescens was compared with the effects of Trifolium pratense L. on soil microbes. High- and low-metal soils were collected near a zinc smelter in Palmerton, Penn. Soil pH was adjusted to 5.8 and 6.8 by the addition of Ca(OH)2. Liming increased bacterial populations and decreased metal toxicity to levels allowing growth of both plants. The effects of the plants on total (culturable) bacteria, total fungi, as well as cadmium- and zinc-resistant populations were assessed in nonrhizosphere and rhizosphere soil. Both plants increased microbial populations in rhizosphere soil compared with nonrhizosphere soil. Microbial populations were higher in soils planted with T. pratense, but higher ratios of metal-resistant bacteria were found in the presence of T. caerulescens. We hypothesize that T. caerutescens acidifies its rhizosphere. Soil acidification in the rhizosphere of T. caerulescens would affect metal uptake by increasing available metals around the roots and consequently, increase the selection for metal-resistant bacteria. Soil acidification may be part of the hyperaccumulation process enhancing metal uptake from soil.     

Diversity and PAH growth abilities of bacterial strains isolated from a contaminated soil in Slovakia

Different abandoned industrial areas contaminated by polycyclic aromatic hydrocarbons (PAHs) are present in Slovakia. These environmental burdens are very dangerous to the health of human and environment. The bioremediation, based on the use of hydrocarbons degrading microorganisms, is a promising strategy to sanitize these polluted sites. The aim of this investigation was to assess the bacterial diversity of a PAHs-contaminated soil and to select the potential hydrocarbonoclastic bacteria which can be used for different bioremediation approaches. The bacterial strains were isolated on minimal medium agar supplemented with a mixture of PAHs. Seventy-three isolated strains were grouped by ribosomal interspacer analysis in 15 different clusters and representatives of each cluster were identified by 16S rRNA sequencing. The PAHs degradation abilities of all bacterial isolates were estimated by the 2,6-dichlorophenol indophenol assay and by their growth on minimal broth amended with a mixture of PAHs. Different kinds of strains, members of the genus Pseudomonas, Enterobacter, Bacillus, Arthrobacter, Acinetobacter and Sphingomonas, were isolated from the contaminated soil. Four isolates (Pseudomonas putida, Arthrobacter oxydans, Sphingomonas sp. and S. paucimobilis) showed promising PAHs-degrading abilities and therefore their possible employing in bioremediation strategies.     

Influence of arbuscular mycorrhizae on photosynthesis and water status of maize plants under salt stress

The influence of arbuscular mycorrhizal (AM) fungus Glomus mosseae on characteristics of the growth, water status, chlorophyll concentration, gas exchange, and chlorophyll fluorescence of maize plants under salt stress was studied in the greenhouse. Maize plants were grown in sand and soil mixture with five NaCl levels (0, 0.5, 1.0, 1.5, and 2.0 g/kg dry substrate) for 55 days, following 15 days of non-saline pretreatment. Under salt stress, mycorrhizal maize plants had higher dry weight of shoot and root, higher relative chlorophyll content, better water status (decreased water saturation deficit, increased water use efficiency, and relative water content), higher gas exchange capacity (increased photosynthetic rate, stomatal conductance and transpiration rate, and decreased intercellular CO(2) concentration), higher non-photochemistry efficiency [increased non-photochemical quenching values (NPQ)], and higher photochemistry efficiency [increased the maximum quantum yield in the dark-adapted state (Fv/Fm), the maximum quantum yield in the light-adapted sate (Fv'/Fm'), the actual quantum yield in the light-adapted steady state (varphiPSII) and the photochemical quenching values (qP)], compared with non-mycorrhizal maize plants. In addition, AM symbiosis could trigger the regulation of the energy biturcation between photochemical and non-photochemical events reflected in the deexcitation rate constants (kN, kN', kP, and kP'). All the results show that G. mosseae alleviates the deleterious effect of salt stress on plant growth, through improving plant water status, chlorophyll concentration, and photosynthetic capacity, while the influence of AM symbiosis on photosynthetic capacity of maize plants can be indirectly affected by soil salinity and mycorrhizae-mediated enhancement of water status, but not by the mycorrhizae-mediated enhancement of chlorophyll concentration and plant biomass.     

Phenanthrene toxicity and dissipation in rhizosphere of grassland plants (Lolium perenne L. and Trifolium pratense L.) in three spiked soils

Rhizodegradation is a technique involving plants that offers interesting potential to enhance biodegradation of persistent organic pollutants such as polycyclic aromatic hydrocarbons (PAHs). Nevertheless, the behaviour of PAHs in plant rhizosphere, including micro-organisms and the physico-chemical soil properties, still needs to be clarified. The present work proposes to study the toxicity and the dissipation of phenanthrene in three artificially contaminated soils (1 g kg^-1 DW). Experiments were carried out after 2 months of soil aging. They consisted in using different systems with two plant species (Ryegrass—Lolium perenne L. var. Prana and red clover—Trifolium pratense L. var. fourragère Caillard), three kinds of soils (a silty-clay-loam soil “La Bouzule”, a coarse sandy-loam soil “Chenevières” and a fine sandy-loam soil “Maconcourt”). Phenanthrene was quantified by HPLC in the beginning (T ₀) and the end of the experiments (30 days). Plant biomass, microbial communities including mycorrhizal fungi, Rhizobium and PAH degraders were also recorded. Generally phenanthrene contamination did not affect plant biomass. Only the red clover biomass was enhanced in Chenevières and La Bouzule polluted soils. A stimulation of Rhizobium red clover colonisation was quantified in spiked soils whereas a drastic negative phenanthrene effect on the mycorrhization of ryegrass and red clover was recorded. The number of PAH degraders was stimulated by the presence of phenanthrene in all tested soils. Both in ryegrass and red clover planted soils, the highest phenanthrene dissipation due to the rhizosphere was measured in La Bouzule soils. On the contrary, in non-planted soils, La Bouzule soils had also the lowest pollutant dissipation. Thus, in rhizospheric and non-rhizospheric soils the phenanthrene dissipation was found to depend on soil clay content.     

Rhizodeposition and the enhanced mineralization of 2,4-dichlorophenoxyacetic acid in soil from the Trifolium pratense rhizosphere

Enhanced biodegradation of organic xenobiotic compounds in the rhizosphere is frequently recorded although the specific mechanisms are poorly understood. We have shown that the mineralization of 2,4-dichlorophenoxyacetic acid (2,4-D) is enhanced in soil collected from the rhizosphere of Trifolium pratense[e.g. maximum mineralization rate=7.9 days-1 and time at maximum rate (t1)=16.7 days for 12-day-old T. pratense soil in comparison with 4.7 days-1 and 25.4 days, respectively, for non-planted controls). The purpose of this study was to gain a better understanding of the plant-microbe interactions involved in rhizosphere-enhanced biodegradation by narrowing down the identity of the T. pratense rhizodeposit responsible for stimulating the microbial mineralization of 2,4-D. Specifically, we investigated the distribution of the stimulatory component(s) among rhizodeposit fractions (exudates or root debris) and the influence of soil properties and plant species on its production. Production of the stimulatory rhizodeposit was dependent on soil pH (e.g. t1 for roots grown at pH 6.5 was significantly lower than for those grown at pH 4.4) but independent of soil inorganic N concentration. Most strikingly, the stimulatory rhizodeposit was only produced by T. pratense grown in non-sterile soil and was present in both exudates and root debris. Comparison of the effect of root debris from plant species (three each) from the classes monocotyledon, dicotyledon (non-legume) and dicotyledon (legume) revealed that legumes had by far the greatest positive impact on 2,4-D mineralization kinetics. We discuss the significance of these findings with respect to legume-rhizobia interactions in the rhizosphere.     

Pollination in vitro: effects on the growth of pollen tubes,seed set and gametophytic self-incompatibility in Trifolium pratense L. and T. repens L.

Summary Growth of pollen tubes and seed set were compared after hand pollination in situ and in vitro in two self-incompatible species, Trifolium pratense and Trifolium repens. Adhesion of pollen grains to the stigma was greater in vitro for both species. After cross-pollination, in vitro culture gave a significant increase in the cumulative growth of pollen tubes in pistils of T. pratense compared to in situ conditions. After selfing in T. repens, pollen tube growth was significantly increased by in vitro culture of florets. Seed set after crossing in situ and in vitro was similar for both species. Seed set after selfing in vitro was not increased in T. pratense. Several genotypes of T. repens were classified as very good, good and poor selfers based on their capacity for seed set following selfing in situ. In vitro pollination increased self seed formation by 1.7-, 18.0- and 31.0-fold for each class, respectively. Ovules located nearest to the style were fertilized more often after selfing than after crossing.     

The effect of growth regulator Tytanit dose on Medicago x varia T. Martin and Trifolium pratense L. yield and nutritional value

The aim of the research was to evaluate the effect of foliar application of different doses of Tytanit as a biostimulant on the yield and nutritional value of Medicago × varia T. Martin and Trifolium pratense L. It was assumed that titanium application during any life cycle of alfalfa hybrid and red clover would contribute to their growth, digestibility, and total protein content. In addition, it was expected that increasing doses of Tytanit up to 0.6 dm³ ha⁻¹ would improve the yield and quality of forage plants. Different doses of Tytanit in different ways affected the yield. However, the largest dose of 0.6 dm³ turned out to be the most effective. It contributed to a 38% increase in the yield of hybrid alfalfa and to a 31% increase in the red clover yield. Individual doses of Tytanit in different ways affected accumulation of protein and crude fibre in the dry matter. Used at 0.4 and 0.6 dm³ doses it increased the amounts of protein and crude fibre relative to control. The smallest dose had no significant effect on these parameters. Tytanit did not improve dry matter digestibility, and there was no statistically significant variation as a result of its application. Foliar application of the biostimulant resulted in an increase in the concentration of phosphorus, potassium, and magnesium in plant dry matter. High content of calcium in the plant species before Tytanit application increased further as a response to 0.2 and 0.4 dm³ doses, with a slight increase in the ratio of K: (Ca + Mg) and an excessive growth of the Ca: P ratio, which reduced hybrid alfalfa and red clover nutritional values. Thus, Tytanit doses used in the experiment significantly increased hybrid alfalfa and red clover yields, but the nutritional value of the plants did not improve.     

Characterization of bacterial communities associated with Brassica napus L. growing on a Zn-contaminated soil and their effects on root growth

The interaction between plant growth-promoting bacteria (PGPB) and plants can enhance biomass production and metal tolerance of the host plants. This work aimed at isolating and characterizing the cultivable bacterial community associated with Brassica napus growing on a Zn-contaminated site, for selecting cultivable PGPB that might enhance biomass production and metal tolerance of energy crops. The effects of some of these bacterial strains on root growth of B. napus exposed to increasing Zn and Cd concentrations were assessed. A total of 426 morphologically different bacterial strains were isolated from the soil, the rhizosphere, and the roots and stems of B. napus. The diversity of the isolated bacterial populations was similar in rhizosphere and roots, but lower in soil and stem compartments. Burkoholderia, Alcaligenes, Agrococcus, Polaromonas, Stenotrophomonas, Serratia, Microbacterium, and Caulobacter were found as root endophytes exclusively. The inoculation of seeds with Pseudomonas sp. strains 228 and 256, and Serratia sp. strain 246 facilitated the root development of B. napus at 1,000 µM Zn. Arthrobacter sp. strain 222, Serratia sp. strain 246, and Pseudomonas sp. 228 and 262 increased the root length at 300 µM Cd.     

In vitro culture and the incidence of somaclonal variation in regenerated plants of Trifolium pratense L.

Red clover (Trifolium pratense L.) cvs ‘Altaswede’ (2n = 2x = 14) and ‘Norseman’ (2n = 4x = 28) have been used to investigate tissue culture initiation, plant regeneration and the occurrence of somaclonal variation. After callus induction shoots were induced both when calli on L2 medium containing 2 mg l⁻¹ 2,4-dichlorophenoxy acetic acid (2,4-D), 2 mg l⁻¹ 6-benzylaminopurine (BA) and 2 mg l⁻¹ 6-amino-purine (AP) were subcultured on media containing naphthalene acetic acid (NAA) (0.05 mg l⁻¹) and kinetin (KIN) (0.05 or 0.5 mg l⁻¹) and when embryogenic calli were cultured and subcultured on L2 medium containing 0.002 mg l⁻¹ 4-amino-3,5,6-trichloropicolinic acid (PIC) and 0.2 mg l⁻¹ BA. Shoot tip cultures were also established to induce multiple shoots for regeneration of plants via organogenesis.Regenerants from different regeneration pathways were evaluated for chromosome number stability, morphology and several biochemical traits. Regenerated plants showed stable isozyme banding patterns for malate dehydrogenase, 6-phosphogluconate dehydrogenase, phosphoglucose isomerase, phosphoglucomutase and shikimate dehydrogenase, as well as their nodule leghemoglobin profiles. Variations were detected in the chromosome number of some regenerants as well as in leaflet length-to-width ratio and leaflet number. Factors related to the incidence of somaclonal variation are discussed.     

Influence of phosphate and ammonia on the growth, exopolysaccharide production and symbiosis of Rhizobium leguminosarum bv. trifolii TA1 with clover (Trifolium pratense)

The Rhizobium-legume interaction is sensitive to a number of environmental factors, among which phosphate (Pi) and ammonium availability are the most important. We investigated the effect of Pi and ammonia concentration on exopolysaccharide production and symbiosis Trifolium pratense with Rhizobium leguminosarum bv. trifolii TA1 (RtTA1). The optimal Pi concentration in the bacterial growth medium for RtTA1 growth and exopolysaccharide production was in the range from 0.9 mM to 8.1 mM. Independently of Pi concentration, ammonium (NH4Cl) concentration above 8.1 mM in the culture medium significantly decreased EPS production, indicating a regulatory role of this nutrient on the EPS production in the RtTA1 strain. Pi availability has a beneficial effect on both partners of symbiosis. Pi concentration in the plant medium in the range from 1.7 mM to 5 mM was optimal for nodule formation, nodule occupancy and nitrogen fixation ability. Despite of T. pratense cv. Bryza tolerance on high Pi concentration, 20 mM Pi occurs to be nearly phytotoxic, which negatively affects almost all symbiotic parameters. Large amounts of starch were accumulated in the nodules formed by clover grown on medium containing high Pi concentration.     

Influence of compaction from wheel traffic and tillage on arbuscular mycorrhizae infection and nutrient uptake by Zea mays

Interactive effects of seven years of compaction due to wheel traffic and tillage on root density, formation of arbuscular mycorrhizae, above-ground biomass, nutrient uptake and yield of corn (Zea mays L.) were measured on a coastal plain soil in eastern Alabama, USA. Tillage and soil compaction treatments initiated in 1987 were: 1) soil compaction from tractor traffic with conventional tillage (C,CT), 2) no soil compaction from tractor traffic with conventional tillage (NC,CT), 3) soil compaction from tractor traffic with no-tillage (C,NT), and, 4) no soil compaction from tractor traffic with no-tillage (NC,NT). The study was arranged as a split plot design with compaction from wheel traffic as main plots and tillage as subplots. The experiment had four replications. In May (49 days after planting) and June, (79 days after planting), root biomass and root biomass infected with arbuscular mycorrhizae was higher in treatments that received the NC,NT treatment than the other three treatments. In June and July (109 days after planting), corn plants that received C,CT treatment had less above-ground biomass, root biomass and root biomass infected with mycorrhizae than the other three treatments. Within compacted treatments, plants that received no-tillage had greater root biomass and root biomass infected with mycorrhizae in May and June than plants that received conventional tillage. Corn plants in no-tillage treatments had higher root biomass and root biomass infected with mycorrhizae than those in conventional tillage. After 7 years of treatment on a sandy Southeastern soil, the interactive effects of tillage and compaction from wheel traffic reduced root biomass and root biomass infected with mycorrhizae but did not affect plant nutrient concentration and yield. ei]J H Graham     

The effect of soil compaction on growth and P uptake by Trifolium subterraneum: interactions with mycorrhizal colonisation

The effects of vesicular-arbuscular mycorrhizal (VAM) colonisation on phosphorus (P) uptake and growth of clover (Trifolium subterraneum L.) in response to soil compaction were studied in three pot experiments. P uptake and growth of the plants decreased as the bulk density of the soil increased from 1.0 to 1.6 Mg m^-3. The strongest effects of soil compaction on P uptake and plant growth were observed at the highest P application (60 mg kg^-1 soil). The main observation of this study was that at low P application (15 mg kg^-1 soil), P uptake and shoot dry weight of the plants colonised by Glomus intraradices were greater than those of non-mycorrhizal plants at similar levels of compaction of the soil. However, the mycorrhizal growth response decreased proportionately as soil compaction was increased. Decreased total P uptake and shoot dry weight of mycorrhizal clover in compacted soil were attributed to the reduction in the root length. Soil compaction had no significant effect on the percentage of root length colonised. However, total root length colonised was lower (6.6 m pot^-1) in highly compacted soil than in slightly compacted soil (27.8 m pot^-1). The oxygen content of the soil atmosphere measured shortly before the plants were harvested varied from 0.18 m³m^-3 in slightly compacted soil (1.0 Mg m^-3) to 0.10 m³m^-3 in highly compacted soil (1.6 Mg m^-3).     

Pollen-stigma Interaction in the Leguminosae: Constituents of the Stylar Fluid and Stigma Secretion of Trifolium pratense L.

The style of T. pratense is hollow, and the canal contains awatery secretion which forms the medium through which the pollentubes grow after penetrating the stigma head. In self-incompatiblegenotypes, incompatible pollen germinates freely and the tubespenetrate the stigma, but they are arrested in the canal afterpassing an inflated zone (entasis) proximal to the stigma head.The stylar fluid contains sucrose, glucose and traces of galactoseand arabinose, as well as a range of proteins. Comparison ofthe proteins in the stigma eluate and stylar fluid by microgradientgel electrophoresis shows that the spectra are broadly similar;but in addition to various minor differences, two major glycoproteinsare present in the stigma secretion which are absent from thestyle, while one in the stylar fluid is not represented in thestigma. Six esterase isoenzymes are present in the stylar fluid,and three of these also in the stigma eluate; there are alsodifferences in acid phosphatase isoenzymes. Leguminosae, Trifolium pratense L., pollen-stigma interaction, self-incompatibility, stigma eluate secretion, stylar secretion     

Studies on strains of Microsporon gypseum isolated from soil

Summary 180 samples collected from different types of soils were examined for presence of dermatophytes.17 strains ofM. gypseum isolated from these samples were studied for their morphology, perfect stage formation and animal pathogenicity. Two isolates could be induced to produce perfect stage,Nannizia incurvata and only one isolate was pathogenic to guinea pig.