Stereotactic radiotherapy for head and neck paragangliomas: How long should we wait for treatment response?

BACKGROUND AND PURPOSE

Stereotactic radiotherapy (SRT) is an effective treatment for head & neck (H&N) paragangliomas. Nevertheless, the timeline for achieving a tumor-volume-reduction (TVR) remains unclear.

MATERIALS AND METHODS

Sixty-three cases with H&N paragangliomas received definitive SRT and were evaluated retrospectively. Statistical Package for the Social Sciences (SPSS) v23.0 (IBM, Armonk, NY, USA) was used for statistics.

RESULTS

Sixty-eight lesions were irradiated, with glomus jugulotympanicum being the most common location (44 %). Median tumor diameter and volume were 3 cm (range, 1-7.6 cm) and 15.4 cm3 (range,1-185 cm3), respectively. Median dose was 25 Gy (range, 12-37.5 Gy) in 5 fractions (range, 1-5 fractions). Median follow-up was 40 months (range, 3-184 months). Treatment response, evaluated at a median 4.6 months post-SRT (range: 3-11 months), revealed TVR in 26 cases (41 %). During follow-up, 13 additional cases showed TVR, resulting in an overall TVR rate of 62 %. The median duration for attaining TVR was 9 months (range, 3-36 months) after SRT, and TVR occurred ≥ 12 months in 42 % of cases. Patients without prior surgery (p = 0.03) and with a longer follow-up (p = 0.04) demonstrated a higher rate of TVR. The likelihood of TVR tends to increase as the SRT dose increases (p = 0.06). Overall local control (LC) rate was 100 %. No ≥ grade 3 acute or late toxicities were observed.

CONCLUSION

While SRT demonstrates an excellent LC rate for H&N paragangliomas, it's important to note that the response to treatment may require time. TVR may last beyond the initial year of treatment in a substantial proportion of patients.

Association of mycoheterotrophic Gentianaceae with specific Glomus lineages

Some plant species took an alternative evolutionary pathway in which they lost their photosynthetic capacity to depend exclusively on carbon supplied by arbuscular mycorrhizal fungi (AMF) in an association called mycoheterotrophy. Among them is Voyriella parviflora, a species of the family Gentianaceae, which is found in tropical regions such as the Amazon basin. Here, we assessed the identity of AMF symbionts associated with this species. DNA was isolated from eight Gentianaceae specimens and from litter and surrounding roots of photosynthetic plants. The atp1 gene was amplified by Sanger sequencing to determine the taxonomic affiliation of the mycoheterotrophic plants. A 280 bp region of the 18S rRNA gene of AMF was amplified with primers NS31/AML2 by high-throughput sequencing. The mycoheterotrophic specimens were assigned to V. parviflora with a bootstrap support of 72%. Glomus was the most abundant AMF genus, both in the mycoheterotrophic plants and in the litter and roots of photosynthetic plants. In addition, a few Glomus genotypes were abundantly enriched in the mycoheterotrophic plants, with only a few specimens colonized by Gigaspora, Acaulospora, and Scutellospora in a low proportion. These genotypes formed a cluster within a larger clade, suggesting that V. parviflora shows a preferential association with a narrow Glomus lineage which is not phylogenetically close to a previously identified V. parviflora's associated lineage. Furthermore, detecting fungi from other families suggests that V. parviflora is colonized by other genera, although with low frequency. These findings provide new insights into the association between AMF and mycoheterotrophic species and highlight the importance of considering trap culture-independent approaches in understanding this symbiosis.

An analysis from the CAPACITY database of outcomes of preoperative embolization before carotid body tumor surgery compared with resection alone

OBJECTIVE

There is no definitive consensus on the impact of preoperative embolization on carotid body tumor (CBT) treatment. The objective of this study was to compare surgical outcomes of patients who underwent preoperative embolization before CBT resection vs patients who underwent resection alone.

METHODS

The CAPACITY registry included 1432 patients with CBT from 11 medical centers in four different countries. The group of patients undergoing CBT resection with preoperative embolization was matched in a 1:6 ratio from a pool of patients from the CAPACITY database, using a generated propensity score with patients who did not underwent preoperative embolization.

RESULTS

A total of 553 patients were included for analysis. Mean patient age was 56.23 ± 12.22 years. Patients were mostly female (n = 469; 84.8%). Bilateral CBT was registered in 60 patients (10.8%). Seventy-nine patients (14.3%) underwent preoperative embolization. Embolized patients had larger CBT sizes than non-embolized patients (33.8 mm vs 18.4 mm; P = .0001). Operative blood loss was lower in the embolized group compared with the non-embolized group (200 mL vs 250 mL; P = .031). Hematomas were more frequent in the non-embolized group (0% vs 2.7%; P = .044). Operative time, rates of stroke, cranial nerve injuries, and death were not statistically significant between groups.

CONCLUSIONS

Embolization before CBT resection was associated with significantly lower blood loss and lower neck hematomas than patients who underwent resection alone. Operative time, stroke, cranial nerve injuries, and death were similar between groups.

Glomus tumor mimicking digital adenocarcinoma

Glomus tumors are uncommon, benign lesions commonly located on the digits of the hands and are diagnostically challenging. This is because hemangiomas or ganglion cysts are more commonly identified in those locations. Our case report underlines the diagnostic challenge of a glomus tumor and the importance of immunohistochemical staining.

Glomus Tumor of the Pterygopalatine Fossa: A Rare Case Report

The pterygopalatine fossa (PPF) is a challenging space and pathological processes in this anatomical space are uncommon. This report presents a case of glomus tumor right PPF in a 65 years old female patient who underwent tumor removal by endoscopic transnasal-transmaxillary approach with preoperative selective embolization of the right internal maxillary artery.

strains mitigate the adverse effects of drought on maize (Zea mays L.)

Maize (Zea mays L.) is an economically important source of food and feed. This species is highly sensitive to drought, which is the most limiting factor for the biomass yield of a crop. Thus, maize cultivation methods should be improved, especially by environment-friendly agricultural practices, such as microorganisms. Here, we provide evidence that Glomus sp. and Bacillus sp. modulate maize response to drought. Inoculation of maize seeds by these microorganisms restored the proper photosynthetic activity of the plant under drought and stabilized the osmoprotectant content of the leaf. The beneficial effect of Glomus sp. and Bacillus sp. was also related to the stabilization of cell redox status reflected by hydrogen peroxide content, antioxidant enzymes, and malondialdehyde level in leaves. As we revealed by several methods, shaping maize response to drought is mediated by both microorganism-mediated modifications of cell wall composition and structure of leaves, such as downregulating pectin, affecting their methylation degree, and increasing hemicellulose content. Overall, we provide new information about the mechanisms by which Glomus sp. and Bacillus sp. induce drought tolerance in maize, which is a promising approach for mitigating abiotic stresses.

The Long-Term Outcome of CyberKnife-Based Stereotactic Radiotherapy for Head and Neck Paragangliomas: A Single-Center Experience

OBJECTIVE

To assess long-term outcomes of hypofractionated stereotactic radiotherapy (hSRT) for head and neck paragangliomas (HNPGs).

METHODS

Patients who underwent hSRT with CyberKnife for HNPGs from 2010 to 2019 were retrospectively reviewed.

RESULTS

A total of 34 HNPGs in 29 patients were identified. Mean patient age was 50 ± 16 years, and 15 patients (52%) were female. Fifteen patients (55%) had undergone previous procedures. Four cases (14%) were functional in hormone production. According to the Fisch classification, 1 (3%) case was B, 12 (42%) cases were C, 14 (48%) cases were D, and 2 (7%) cases were unclassified.¹ The median prescribed dose covering 95% of the planning target volume was 2500 cGy (interquartile range 2100-2600 cGy), and the median target volume was 10 cm³ (interquartile range 6.0-18.3 cm³). The local control rate was 97%. The median progression-free survival was 66 months (interquartile range 28-95 months), and 96% of patients were free of tumor progression at 8 years. During follow-up, 1 case (3%) resulted in permanent facial nerve palsy (House-Brackmann grade II), and another case (3%) resulted in asymptomatic cerebellar radiation necrosis. Univariate and multivariate analysis showed that no previous surgical history (odds ratio 8.58, 95% confidence interval 1.2-59.7, P = 0.03) was a positive predictor of symptomatic improvement.

CONCLUSIONS

hSRT for HNPGs was an effective treatment with minimal side effects over the long term and may have a role as first-line therapy, especially for symptomatic nonfunctional HNPGs, for better symptom control.

Enigmatic and Unusual Cases of Upper Extremity Pain: Mislabeling As Malingerers

With the intricate anatomy of the hand and upper extremity, there are many possible etiologies of pain. In addition, one must be alert to conditions typically affecting other areas of the body presenting in the hand and upper extremity. To add to the complexity of diagnosis, one must also be aware of potential secondary gains. With this in mind, a thorough history, physical examination, and broad differential can help avoid mislabeling patients with uncommon ailments. In this article, we present 4 cases of unusual causes of hand and upper extremity pain.

Extradigital glomus tumor of the anterior knee

The benign glomus tumor is an uncommon cause of crippling pain most commonly associated with the fingers. This sheep in wolf’s clothing is identified by careful examination, confirmed by MRI, and often resolved with a simple procedure. Here we present a patient with chronic knee pain of 21 years duration.

Inoculation with arbuscular mycorrhizal fungi alleviates harmful effects of drought stress on damask rose

This study was conducted to examine the role of arbuscular mycorrhiza fungi (AMF) in alleviating the adverse effects of drought stress on damask rose (Rosa damascena Mill.) plants. Four levels of drought stress (100, 75, 50, and 25% FC) were examined on mycorrhizal and non-mycorrhizal plants in pots filled with sterilized soil. Our results showed that increasing drought stress level decreased all growth parameters, nutrient contents, gas exchange parameters, and water relations indicators. Under different levels of drought stress, mycorrhizal colonization significantly increased all studied parameters. P n, g s, and E of the mycorrhizal plants was higher than those of non-mycorrhizal plants under different levels of drought stress. The increase in those rates was proportional the level of the mycorrhizal colonization in the roots of these plants. Majority of growth, nutrition, water status and photosynthetic parameters had a great dependency on the mycorrhizal colonization under all levels of drought stress. The results obtained in this study provide a clear evidence that AMF colonization can enhance growth, flower quality and adaptation of rose plants under different drought stress levels, particularly at high level of drought stress via improving their water relations and photosynthetic status. It could be concluded that colonization with AMF could help plants to tolerate the harmful effects caused by drought stress in arid and semi-arid regions.

Physiological response of Cucurbita pepo var. pepo mycorrhized by Sonoran desert native arbuscular fungi to drought and salinity stresses

Plants response to symbiosis with arbuscular mycorrhizal fungi (AMF) under water stress is important to agriculture. Under abiotic stress conditions native fungi are more effective than exotics in improving plant growth and water status. Mycorrhization efficiency is related to soil fungi development and energy cost-benefit ratio. In this study, we assessed the effect on growth, water status and energy metabolism of Cucurbita pepo var. pepo when inoculated with native AMF from the Sonoran desert Mexico (mixed isolate and field consortium), and compared with an exotic species from a temperate region, under drought, low and high salinity conditions. Dry weights, leaf water content, water and osmotic potentials, construction costs, photochemistry and mycorrhization features were quantified. Under drought and low salinity conditions, the mixed isolate increased plant growth and leaf water content. Leaf water potential was increased only by the field consortium under drought conditions (0.5-0.9MPa). Under high salinity, the field consortium increased aerial dry weight (more than 1g) and osmotic potential (0.54MPa), as compared to non-mycorrhized controls. Plants inoculated with native AMF, which supposedly diminish the effects of stress, exhibited low construction costs, increased photochemical capacity, and grew larger external mycelia in comparison to the exotic inoculum.

Brace yourself: an unusual case of knee pain, an extradigital glomangioma of the knee

The differential diagnosis for knee pain is extensive. Glomus tumors comprise approximately 1.6% of soft-tissue tumors in the extremities. Classic subungual tumors occur more frequently in women, whereas ectopic locations are more common in men. Unusual locations include the stomach; lungs; trachea; bones; intestines; fallopian tubes; and intraneural, neuromal, and intravenous locations. We present the case of a 50-year-old man with a 12-year history of enlarging right knee mass found to be a glomangioma. This case report discusses the incidence, presentation, imaging characteristics, histology, and management of glomus tumors of the knee.

Spinal Glomus Arteriovenous Malformation Manifesting with a Subarachnoid Hemorrhage

BACKGROUND

Spinal arteriovenous malformations (AVMs) are rare lesions that may cause serious neurologic morbidity. With developments in endovascular technology and embolic materials, endovascular management of spinal AVMs has gained popularity.

CASE DESCRIPTION

A 61-year-old woman presented with the worst headache of her life and an acute onset of nausea and vomiting and was shown to have a grade 2 subarachnoid hemorrhage (SAH) on computed tomography scan. A 6-vessel cerebral angiogram was negative for any vascular abnormalities. Magnetic resonance imaging and magnetic resonance angiography of the neck showed a flow-related enhancement compatible with a vascular abnormality at the level of C2. Cervical spinal angiography showed a cervical spinal cord glomus (type II) AVM at the level of C2 draining into perimedullary venous plexus. Transarterial Onyx embolization was performed and resulted in complete occlusion of the AVM. The patient made a complete neurologic recovery.

CONCLUSIONS

Spinal AVMs manifesting as intracranial SAH are uncommon. These lesions are frequently overlooked on cerebral angiography and account for a small proportion of angiogram-negative SAHs. A negative angiogram in the setting of SAH should prompt a comprehensive evaluation of the cervical segmental arterial supply to exclude a cervical spinal AVM. Endovascular embolization may be effective in treating spinal glomus AVMs with good clinical outcomes and with complete angiographic obliteration. Onyx embolic agent should be considered as the agent of choice to manage spinal glomus AVMs.

Synergistic effects of Arbuscular mycorrhizal fungi and plant growth promoting rhizobacteria in bioremediation of iron contaminated soils

Three Arbuscular mycorrhizal fungi (AMF) from Glomus, Acaulospora and Scutellospora, and four plant growth promoting rhizobacteria (PGPR) isolates related to genera Streptomyces, Azotobacter, Pseudomonas and Paenibacillus were found to be effective in phytoremediation of Fe(3+) contaminated soil where Pennisetum glaucum and Sorghum bicolor were growing as host plants. Co-inoculation of AMF and PGPR showed better results in comparison to either, AMF and PGPR under pot conditions. Both AMF and PGPR were able to produce siderophores. AMF and PGPR associated to P. glaucum and S. bicolor plants increased the extent of iron absorption. AMF and PGPR combination exhibited superior (p < 0.01) phytoremediation efficiency with P. glaucum compared to S. bicolor. These findings warrant further investigations of these synergistic interactions and large-scale in situ studies for bioremediation of iron-contaminated soils.

Expanding genomics of mycorrhizal symbiosis

The mycorrhizal symbiosis between soil fungi and plant roots is a ubiquitous mutualism that plays key roles in plant nutrition, soil health, and carbon cycling. The symbiosis evolved repeatedly and independently as multiple morphotypes [e.g., arbuscular mycorrhizae (AM), ectomycorrhizal (ECM)] in multiple fungal clades (e.g., phyla Glomeromycota, Ascomycota, Basidiomycota). The accessibility and cultivability of many mycorrhizal partners make them ideal models for symbiosis studies. Alongside molecular, physiological, and ecological investigations, sequencing led to the first three mycorrhizal fungal genomes, representing two morphotypes and three phyla. The genome of the ECM basidiomycete Laccaria bicolor showed that the mycorrhizal lifestyle can evolve through loss of plant cell wall-degrading enzymes (PCWDEs) and expansion of lineage-specific gene families such as short secreted protein (SSP) effectors. The genome of the ECM ascomycete Tuber melanosporum showed that the ECM type can evolve without expansion of families as in Laccaria, and thus a different set of symbiosis genes. The genome of the AM glomeromycete Rhizophagus irregularis showed that despite enormous phylogenetic distance and morphological difference from the other two fungi, symbiosis can involve similar solutions as symbiosis-induced SSPs and loss of PCWDEs. The three genomes provide a solid base for addressing fundamental questions about the nature and role of a vital mutualism.

Unusual presentation of glomus tympanicum tumour: New bone formation in the middle ear

The objective of this study is to increase awareness of the rare presentation, diagnostic difficulties and management of glomus tympanicum of the middle ear. A 49 years old male, with a background of hypertension and epilepsy, presented with a two month history of left sided conductive hearing loss, pulsatile tinnitus and headache. Clinically and radiologically a diagnosis of glomus tympanicum was made. Intraoperatively, extensive osteogenesis of the middle ear resulting in ossicular fixation and erosion was found. This patient required a two stage operation for full clearance of disease. A stapedectomy drill was used to drill off the bony overgrowth surrounding the ossicles resulting in improved hearing thresholds and full clearance of the disease at two year follow up. Glomus tympanicum can result in new bone formation in the middle ear with resultant ossicular fixation and conductive hearing loss. This can be effectively treated surgically with restoration of hearing.

A Glomus Tumour of the Elbow: A Case Report and Review of the Literature

Extradigital glomus tumours are relatively uncommon. We present a case report of a glomus tumour of the elbow and review of the literature with regards to the clinical features, work-up and management of these tumours, to highlight the importance of considering a glomus tumour as part of the differential diagnosis in patient with atypical pain around the elbow.

Direct and indirect influences of arbuscular mycorrhizal fungi on phosphorus uptake by two root hemiparasitic Pedicularis species: do the fungal partners matter at low colonization levels?

BACKGROUND AND AIMS

Because most parasitic plants do not form mycorrhizal associations, the nutritional roles of arbuscular mycorrhizal (AM) fungi in them have hardly been tested. Some facultative root hemiparasitic Pedicularis species form AM associations and hence are ideal for testing both direct and indirect effects of AM fungi on their nutrient acquisition. The aim of this study was to test the influence of AM inoculation on phosphorus (P) uptake by Pedicularis rex and P. tricolor.

METHODS

(32)P labelling was used in compartmented pots to assess the contribution of the AM pathway and the influence of AM inoculation on P uptake from a host plant into the root hemiparasites. Laboratory isolates of fungal species (Glomus mosseae and G. intraradices) and the host species (Hordeum vulgare 'Fleet') to which the two Pedicularis species showed obvious responses in haustorium formation and growth in previous studies were used.

KEY RESULTS

The AM colonization of both Pedicularis spp. was low (<15 % root length) and only a very small proportion of total plant P (<1 %) was delivered from the soil via the AM fungus. In a separate experiment, inoculation with AM fungi strongly interfered with P acquisition by both Pedicularis species from their host barley, almost certainly because the numbers of haustoria formed by the parasite were significantly reduced in AM plants.

CONCLUSIONS

Roles of AM fungi in nutrient acquisition by root parasitic plants were quantitatively demonstrated for the first time. Evidence was obtained for a novel mechanism of preventing root parasitic plants from overexploiting host resources through AM fungal-induced suppression of the absorptive structures in the parasites.

Occurrence of Arbuscular Mycorrhizal Fungi in Rhizosphere of Jatropha curcas L. in Arid and Semi Arid Regions of India

A study was conducted to identify common arbuscular mycorrhizal (AM) fungi present in rhizosphere of Jatropha curcas L., an important bio-diesel crop, from different arid and semi arid regions of India viz., Jodhpur (Rajasthan), Hissar (Haryana), Jhansi and Lalitpur (Uttar Pradesh) and Hyderabad (Andhra Pradesh). A total of 20 AM species were recorded, which consisted of two species of Acaulospora and 18 species of Glomus. The highest frequency of occurrence was recorded for Glomus intraradix (100%), followed by Acaulospora scrobiculata (83%), G. etunicatum (50%) and Glomus 1 (50%). Maximum species richness was recorded at Jodhpur, followed by Jhansi, Hissar, Hyderabad and Lalitpur. The results seem to suggest that species richness was more in arid regions as compared to semi arid areas.

Influence of Inoculation with the Endomycorrhizal Fungi and Trichoderma viride on Morphological and Physiological Growth Parameters of Rauwolfia serpentina Benth. Ex. Kurtz

Two arbuscular mycorrhizal fungi, Glomus mosseae and Acaulospora laevis either alone or in combination with Trichoderma viride showed the dependence of Rauwolfia serpentina on endomycorrhizal fungi. After 60 days, G. mosseae singly or in combination with Trichoderma viride showed enhanced height increment compared to control plants. Maximum phosphorus content was shown by plants treated with G. mosseae plus T. viride (0.444 ± 2.62) in roots and (0.437 ± 4.71) in shoots. Phosphorus content in roots was more than that in shoots. Chlorophyll content and stomatal conductivity also showed similar trend.

AM Fungal Diversity in Selected Medicinal Plants of Kanyakumari District, Tamil Nadu, India

The association of Arbuscular Mycorrhizal Fungi (AMF) with three medicinally important plants viz., Eclipta prostrata, Indigofera aspalathoides, I. tinctoria collected from three different localities of Kanyakumari District, South India was examined. The study reports the colonization percentage, diversity and species richness of different AM fungi in the rhizosphere of the three medicinal plants and discusses the impact of soil physicochemical characteristics such as soil texture, pH and available macro- and micro nutrient content on AM fungal communities. A total 21 AM fungal species were identified in field conditions of the three plants from three sites. AM fungal species richness, colorization percentage and Shannon index were found to be high in the two Indigofera sp. growing in the hilly areas of Kanyakumari District and were low in E. prostrata collected from the damp regions in the foothills of the three study sites. Five species registered 100% frequency in all the study sites of the three medicinally important plants with Glomus as the dominant genera. The study states that the mean colonization and diversity patterns were dependant on edaphic factors and type of vegetation.

The Distribution of Cytoplasm and Nuclei within the Extra-radical Mycelia in Glomus intraradices, a Species of Arbuscular Mycorrhizal Fungi

Nuclear distribution within the extra-radical fungal structures and during spore production in the arbuscular mycorrhizae fungus Glomus intraradices was examined using an in vitro monoxenic culture system. A di-compartmental monoxenic culture system was modified using a nitrocellulose membrane and a coverglass slip for detailed observations. Nuclear distribution was observed using the fluorescent DNA binding probes SYBR Green I and DAPI. Both septate and non-septate mycelial regions were observed, but cytoplasmic contents were only found within non-septate mycelia. Nuclear fluorescent staining revealed that the non-septate hyphal region contained nuclei only with cytoplasm, and that nuclear distribution was limited by septa. Swollen hyphal bodies were often associated with septate and empty-looking hyphae. Cytoplasmic contents filled the swollen hyphal body from the non-septate hyphal region following removal of the septa. As a consequence, the swollen body developed into a new spore. These observations provide understanding about the distribution of AM fungal nuclei within extra-radical mycelia and during spore formation. The results suggest a mechanism by which the development of a cytoplasm-containing mycelium is controlled by the formation or removal of septa to efficiently maintain and proliferate essential contents. This mechanism may provide a survival strategy to the fungus.

Effects of interspecific interactions of arbuscular mycorrhizal fungi on growth of soybean and corn

Growth responses of Zea mays and Glycine max to colonization by mixture of combination of three species of arbuscular mycorrhizal (AM) fungi, two species of Glomus and a species of Scutellospora were compared. In Zea mays, plants inoculated with single species of AM fungi showed significantly higher in dry weight than non-mycorrhizal plant for all three AM fungal species. Also, growth of plants inoculated with spores of two species of AM fungi was significantly higher than nonmycorrhizal control except for plants inoculated with two Glomus species. When three species of AM fungi were inoculated, the plants showed the highest growth. In Glycine max, plants with single AM fungal species inoculation were not significantly different in plant growth from nonmycorrhizal plants. When the plants were inoculated with combination of two or more AM fungal species, their growth significantly increased compared to nonmycorrhizal plants. In both plant species, mycorrhizal root colonization by Scutellospora species was significantly lower than by Glomus species.

Increased Salinity Tolerance of Cowpea Plants by Dual Inoculation of an Arbuscular Mycorrhizal Fungus Glomus clarum and a Nitrogen-fixer Azospirillum brasilense

Pot greenhouse experiments were carried out to attempt to increase the salinity tolerance of one of the most popular legume of the world; cowpea; by using dual inoculation of an Am fungus Glomus clarum and a nitrogen-fixer Azospirillum brasilense. The effect of these beneficial microbes, as single- or dual inoculation-treatments, was assessed in sterilized loamy sand soil at five NaCl levels (0.0~7.2 ds/m) in irrigating water. The results of this study revealed that percentage of mycorrhizal infection, plant height, dry weight, nodule number, protein content, nitrogenase and phosphatase activities, as well as nutrient elements N, P, K, Ca, Mg were significantly decreased by increasing salinity level in non-mycorrhized plants in absence of NFB. Plants inoculated with NFB showed higher nodule numbers, protein content, nitrogen concentration and nitrogenase activities than those of non-inoculated at all salinity levels. Mycorrhized plants exhibited better improvement in all measurements than that of non-mycorrhized ones at all salinity levels, especially, in the presence of NFB. The concentration of Na(+) was significantly accumulated in cowpea plants by rising salinity except in shoots of mycorrhizal plants which had K(+)/Na(+) ratios higher than other treatments. This study indicated that dual inoculation with Am fungi and N-fixer Azospirillum can support both needs for N and P, excess of NaCl and will be useful in terms of soil recovery in saline area.

Role of arbuscular mycorrhizal fungi in phytoremediation of soil rhizosphere spiked with poly aromatic hydrocarbons

Results from an innovative approach to improve remediation in the rhizosphere by encouraging healthy plant growth and thus enhancing microbial activity are reported. The effect of arbuscular mycorrhizal fungi (Am) on remediation efficacy of wheat, mungbean and eggplant grown in soil spiked with polyaromatic hydrocarbons (PAH) was assessed in a pot experiment. The results of this study showed that Am inoculation enhanced dissipation amount of PAHs in planted soil, plant uptake PAHs, dissipation amount of PAHs in planted versus unplanted spiked soil and loss of PAHs by the plant-promoted biodegradation. A number of parameters were monitored including plant shoot and root dry weight, plant tissue water content, plant chlorophyll, root lipid content, oxido-reductase enzyme activities in plant and soil rhizosphere and total microbial count in the rhizospheric soil. The observed physiological data indicate that plant growth and tolerance increased with Am, but reduced by PAH. This was reflected by levels of mycorrhizal root colonization which were higher for mungbean, moderate for wheat and low for eggplant. Levels of Am colonization increased on mungbean > wheat > eggplant. This is consistent with the efficacy of plant in dissipation of PAHs in spiked soil. Highly significant positive correlations were shown between of arbuscular formation in root segments (A)) and plant water content, root lipids, peroxidase, catalase polyphenol oxidase and total microbial count in soil rhizosphere as well as PAH dissipation in spiked soil. As consequence of the treatment with Am, the plants provide a greater sink for the contaminants since they are better able to survive and grow.

24-Methyl/methylene sterols increase in monoxenic roots after colonization by arbuscular mycorrhizal fungi

•  Characteristic sterols of transformed carrot (Daucus carota) and chicory (Cichorium intybus) roots colonized by different strains of arbuscular mycorrhizal (AM) fungi were identified. •  Sterols were extracted, analysed and identified by gas chromatography/mass spectrometry (GC-MS) from monoxenic cultures of mycorrhizal and nonmycorrhizal roots. After colonization by Glomus intraradices, Glomus proliferum and Glomus sp., carrot and chicory roots exhibited a significantly higher 24-methyl/methylene sterol content. A correlation was established between the content of the sum of 24-methyl cholesterol, 24-methylene cholesterol and 24-methyl desmosterol. •  This study clearly established that the increment of these characteristic sterols is an appropriate indicator of colonization by AM fungi of transformed roots. •  Metabolic origin and specificity of these sterols in mycorrhizal roots was researched. The 24-methyl/methylene sterol increase was observed only when the interaction between fungus and plant was completely established and the fungus was present inside the roots.

Phospho-imaging as a tool for visualization and noninvasive measurement of P transport dynamics in arbuscular mycorrhizas

• A new method is described for monitoring hyphal ³² P transport in compartmented, monoxenic mycorrhizal root cultures. Nondestructive time-course measurements of P transport in hyphae were obtained by capturing digital autoradiograms on P-imaging screens, and comparing with growth observed by optical scanning. ³² P distribution measured by densitometry on the day of harvest closely agreed with values obtained by liquid scintillation counting after destructive harvest. • Virtually all labeled PO₄ was absorbed by arbuscular mycorrhizal (AM) hyphae, but transfer to the roots appeared to be incomplete. P transport was not unidirectional towards the roots, as ³² P was also transported from the root compartment to the hyphal compartment. Net P flux rates were calculated for hyphae crossing between compartments, taking bidirectional flow into account. • Amounts of transported P were poorly correlated with extra-radical hyphal length and root d. wt, but highly correlated with the number of hyphae crossing the barrier separating the two compartments. Such correlations were highest when only hyphae with detectable protoplasmic streaming were considered. • The method was tested using radiolabeled P sources, H₂ PO₄ ^- and cytidine triphosphate (CTP), and the AM fungi, Glomus intraradices and G. proliferum. Fungal transport of ³² P from CTP was much slower than from PO₄ for both fungi.

Cross walls in arbuscular trunk hyphae form after loss of metabolic activity

•  A time-course of Allium porrum colonized by Glomus coronatum examined the formation of cross walls in arbuscular trunk hyphae in relation to the development and senescence of arbuscules. •  Mycorrhizal structures visualized using nitroblue tetrazolium as a vital stain indicated metabolically active arbuscules and intercellular hyphae with counterstaining by acid fuchsin. The intrahyphal location and intact nature of cross walls was examined using confocal microscopy. Their presence was correlated with the metabolic status of the mycorrhizal unit (i.e. arbuscule branches, arbuscular trunk hypha and intercellular hypha) using an interdependence magnified intersects technique (IMIT). •  Loss of metabolic activity was observed first from arbuscule branches, then from trunk hypha and lastly from intercellular hyphae. Cross walls were seen in trunk hyphae of many inactive arbuscules. The incidence of cross walls increased with time and was associated with loss of activity. •  Observations suggest cross walls appeared after loss of metabolic activity in arbuscule branches in several plant-fungal combinations. The implications of cross-wall formation for mechanisms of transfer of nutrients between fungus and plant are discussed.

Differences in glucosinolate patterns and arbuscular mycorrhizal status of glucosinolate-containing plant species

Under defined laboratory conditions it was shown that two glucosinolate-containing plant species, Tropaeolum majus and Carica papaya, were colonized by arbuscular mycorrhizal (AM) fungi, whereas it was not possible to detect AM fungal structures in other glucosinolate-containing plants (including several Brassicaceae). Benzylglucosinolate was present in all of the T. majus cultivars and in C. papaya it was the major glucosinolate. 2-Phenylethylglucosinolate was found in most of the non-host plants tested. Its absence in the AM host plants indicates a possible role for the isothiocyanate produced from its myrosinase-catalysed hydrolysis as a general AM inhibitory factor in non-host plants. The results suggest that some of the indole glucosinolates might also be involved in preventing AM formation in some of the species. In all plants tested, both AM hosts and non-hosts, the glucosinolate pattern was altered after inoculation with one of three different AM fungi (Glomus mosseae, Glomus intraradices and Gigaspora rosea), indicating signals between AM fungi and plants even before root colonization. The glucosinolate induction was not specifically dependent on the AM fungus. A time-course study in T. majus showed that glucosinolate induction was present during all stages of mycorrhizal colonization.

Scutellospora calospora (Nicol. & Gerd.) Walker & Sanders associated with subterranean clover produces non-infective hyphae during sporulation

Subterranean clover (Trifolium subterraneum L.) inoculated with either Scutellospora calospora (Nicol. & Gerd.) Walker & Sanders or Glomus sp. (WUM 10(1)) was grown in 3 kg of Lancelin sand surrounding a fine mesh bag (< 38 μm) filled with 400 g of steamed sand. The mesh size was chosen to allow hyphae to penetrate but to exclude plant roots. Every week, from 3 wk after planting the original plants, subterranean clover seeds were sown into the sand inside the mesh bags. The last sowing date was 8 wk from sowing of the original plants. The seedlings, with their roots growing inside the mesh bags, were allowed to grow for 3 wk. At that stage the seedlings and the original plants were harvested and their roots assessed for mycorrhizal colonization. The percentage of root length of the original plants colonized by S. calospora decreased from the first harvest onwards, while colonization by Glomus sp. maintained a similar level at all harvests. Seedlings growing in pots whose original plants were colonized by S. calospora had a her percentage of root length colonized at the first two harvests but levels of Colonization decreased substantially thereafter. Seedlings in the Glomus sp. treatment on the other hand, had similar levels of colonization at all but the last harvest. The length of hyphae g^-1 soil in the mesh hues increased throughout the experiment for both fungi. However, the length of hyphae in the S. calospora treatment increased at a faster rate. Spore production by S. calospora commenced 7 wk after sowing the original plants. These results indicate that the hyphae produced by S. colospora after internal colonization had stopped increasing were largely non-infective, and that these hyphae are primarily involved in the production of spores.

Further evidence for a correlation between nodulation genotypes in alfalfa (Medicago sativa L.) and mycorrhiza formation

The vesicular-arbuscular (VA) mycorrhizal status of three alfalfa (Medicago sativa L.) nodulation genotypes (nod⁺ fix⁺ , nod⁺ fix^- and nod^- fix^- ) was investigated using pot cultures of three fungal species from two genera (Glomus monosporum Gerd. & Trappe, Glomus fasciculatum (Thaxter) Gerd. & Trappe emend. Walker & Koske and Gigaspora margarita Becker & Hall). Roots of the nod⁺ fix⁺ genotype developed complete VA mycorrhizas with each fungus. Roots of the nod⁺ fix^- and nod^- fix^- genotypes did not develop normal VA mycorrhizal symbioses. Roots of the nod^- fix^- genotype had significantly more appressoria than roots of the other genotypes. Aborted appressoria were unable to penetrate the cortical cells of roots of nod⁺ fix^- and nod^- fix^- genotypes. Measurement of appressorium length, width and approximate contact area revealed significant differences in the size of appressoria produced by each VA mycorrhizal fungus on each alfalfa nodulation genotype. Histological studies of nod⁺ fix⁺ and nod^- fix^- genotypes colonized by Glomus versiforme (Karsten) Berch showed the presence of electron-dense material in aborted appressoria on roots of the nod^- fix^- genotype but not in appressoria on roots of the nod⁺ fix⁺ genotype.

The effect of magnesium ions on the vesicular-arbuscular mycorrhizal infection of maize roots

The effect of magnesium sulphate on the colonization of maize roots by a vesicular-arbuscular mycorrhizal fungus was studied in hydroponic culture. Increased concentration of MgSO₄ in the nutrient solution caused an increase in the percentage of root length infected. The highest infection levels were found when nutrient solutions contained 5 84-11.68 mmol 1^-1 of MgSO₄ . Root colonization was stimulated by the increased concentration of magnesium but not calcium or potassium ions in the nutrient solution. No significant difference occurred in the percentage of root length infected when magnesium chloride was replaced by magnesium sulphate. A broad range of magnesium sulphate concentrations did not cause significant differences in plant biomass. The stimulation of root colonization by magnesium cannot be explained by changes in pH or osmotic pressure of the nutrient solution.

Interactions between three alfalfa nodulation genotypes and two Glomus species

Seedlings of a non-nodulating alfalfa (Medicago sativa L.) genotype (nod^- fix^- ) and an ineffectively nodulating alfalfa genotype (nod⁺ fix^- ) exhibited resistance to vesiscular-arbuscular mycorrhizal (VA mycorrhizal) colonization, when grown in pot cultures inoculated with either Glomus versiforme (Daniels and Trappe) Berth or Glomus intraradices Schenck and Smith. Appressoria, showing considerable variation in size and shape, developed on the root surface, but failed to form any internal structures such as arbuscules and vesicies. Wild-type (nod⁺ fix^- ) alfalfa seedlings developed normal colonization. This phenomenon will be extremely useful in studying the processes of recognition and compatibility between plant species and VA mycorrhizal fungal species.

RESPONSES OF THREE VESICULAR - ARBUSCULAR MYCORRHIZAL FUNGI AT FOUR SOIL TEMPERATURES AND THEIR EFFECTS ON COTTON GROWTH

The effects of four soil temperatures on growth of Stoneville 213 cotton (Gossypium hirsutum L.) and root colonization by three vesicular-arbuscular mycorrhizal fungi were tested in soil temperature tanks in the glasshouse. Growth responses in fresh and dry weights of shoots and plant height were linear for noninoculated plants, but nonlinear for plants mycorrhizal with Glomus intraradices Schenck & Smith, Glomus ambisporum Smith & Schenck, or Gigaspora margarita Becker & Hall at soil temperatures of 18, 24, 30 and 36 °C. Total length of root and length of mycorrhizal root were positively correlated and increased as soil temperatures increased. However, total root length was not significantly changed by soil temperature in nonmycorrhizal plants. At 18 °C, shoot and root growth were not improved by mycorrhizas and total root length was actually suppressed by the endophytes. At 24, 30, and 36 °C, mycorrhizas stimulated plant growth. Shoot dry weights were maximum at 30 °C on plants mycorrhizal with G. margarita and G. intraradicvs and at 36 °C on plants inoculated with G. ambisporutn. Percent root colonization by the endophytes was less than 10% at 18 °C and ranged from 57 to 80% at temperatures of 24 °C or higher. All mycorrhizal plants had increased leaf tissue concentrations of P, Cu, Zn, and Mn with concentrations of Cu, Zn, and Mn greatest in plants mycorrhizal with G. ambisporum. The three mycorrhizal fungi generally stimulated plant growth equally well at 24 and 30 °C and G. ambisporum was slightly more effective as a symbiont at 36 °C than either G. intraradices or G. margarita.