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Adivevappar, Nagarajappa. 2001. Effect of VAM fungi on growth, yield and Drought tolerance of Papaya. University of Agricultural Sciences, Dharwad- 580 005 Karnataka state, India.


Title: The abundance and distribution of arbuscular mycorrhizal fungi in saline soils of the Tabriz Plain and their inoculation effects on the improvement of salt tolerance in onion and barley.
Author: ALIASGHARZADEH, N.
Degree: PH.D
Advision: (Major advisor) Professor Saleh Rastin,N.
Year: January, 2001
Institution: Department of Soil Science
Faculty of Agriculture
University of Tabriz
Tabriz,51664
IRAN
Fax:+98 (411) 3345332
E-mail: n-aliasghar@ark.tabrizu.ac.ir


Title: Foliar drought tolerance of mycorrhizal and nonmycorrhizal cowpea, soybean, bush bean and basil.
Author: Kubikova, Elena
Degree: M.S.
Supervisor: Auge', RM
Institution: Institute of Agriculture, University of Tennessee
Year: 2001
SUMMARY: The objective of this research was to compare the ability of mycorrhizal (M) plants (Glomus intraradices) and nonmycorrhizal plants to withstand dehydration. The legume experiment with cowpea (Vigna unguiculata), soybean (Glycine max L) and bush bean (Phaseolus vulgaris) and the basil experiments were conducted using three treatments: mycorrhizal (M),nonmycorrhizal with low phosphorus (NL), and nonmycorrhizal with high phosphorus (NH). Soybean, bush bean, cowpea and basil plants were exposed to slow, continuous drying episode and drought tolerance of intact foliage was studied. Drying episode continued until plants reached the lethal point, described in terms of leaf water potential (Q), or the water potential of the last surviving leaves. Stomatal conductance, osmotic adjustment, lethal soil matric potential (Qm ) and lethal leaf Q were measured to determine soil and leaf water status of M vs. NL or NH plants. Lethal leaf Q and soil matric Qm values did not differ among treatments in both experiments, except for soybean plants with NL treatment where -3.60 MPa compared to -3.19 for M treatment and -3.33 for NH treatment. Cowpea NL plants developed more osmotic adjustment than NH cowpea plants. Basil M plants had osmotic adjustment 0.16 MPa if compared to 0.06 and 0.08 MPa in NL or NH plants. Differences in lethal leaf Q among treatments would indicate that mycorrhizal symbiosis has changed the physiology of the host plant. Our experiments did not show differences in foliar dehydration tolerance or avoidance, but it helped plants osmotically adjust during drought on the example of basil.


Lahlali R. 2001. Amplification en aéroponie de trois espèces mycorhiziennes et mycorhization de certaines variétés de porte-greffes d'agrumes. Mémoire de 3 ème cycle (Master of plant pathology). ENAM, Maroc. 88p.
Abstract:The study was conducted in two parts. The first part concerned the amplification of three species of VAM, Glomus mosseae, G. intraradices and Sclerocystis sp. in aeroponic conditions. The second part consisted in two expriments. the first expriment aimed to evaluate the dependency on mycorrhization of five rootstock seelings: Sour orange (Citrus aurantium L.), Volkamer lemon (Citrus volkameriana), Carrizo citrange (Poncirus trifoliata (L) Raf. x C. sinensis (L.) Osbeck), Troyer citrange (Poncirus trifoliata (L) Raf. x C. sinensis (L.) Osbeck) and Trifoliate orange (Poncirus trifoliata (L). Raf.). The second expriment was designed to identify substrates permitting the best growth of mycorrhizal plants of Citrus volkameriana and Poncirus trifoliata by G. mosseae and G. intraradices.
The results obtained with amplification of three VAM species in aeroponic conditions showed that the genus Glomus adapt well to this culture technique. Indeed, root colonization rate by Glomus mosseae was 53.71 % in sorgum and 18.15 % in corn. The same species produced an average number of spores of 20.83 and 3.10 per centimeter of roots of sorghum and corn respectively. G. intraradices showed colonization rates 34.12 % and 50.74 % in roots of corn and sorgum respectively. In spite of the adjustment of Ph of the nutritive solution, Sclerocystis showed low intensities of mycorrhization. The two species of Glomus allowed a better production of vesicles, while these entities remain absent in Sclerocystis sp. The mycorrhization favored a denser root system with more ramification compared as to the check.
The five Citrus rootstock responded differently to the mycorrhization by both VAM species. All seedling citrus inoculated with both VAM species showed a greater shoot growth, larger stem diameter and larger leaf area compared to the nonmycorrhizal seedlings. Sour orange and Volkamer lemon seedlings are highly dependent of mycorrhizae. The frequencies and the intensities of mycorrhization are significantly affected by the variety of citrus. They are high in the rootstock seedlings infected by Glomus intraradices.
The expriment with substrates showed the mixtures "sand + peat" and "sand + peat + perlite" gave a better growth rate than mixture of "sand + perlite". The frequencies and the intensities of mycorrhization are not significantly affected by the substrate.


Title: Developmentally regulated proteins in Pinus sylvestris roots and ectomycorrhiza.
Author: Tarkka, M.T.
Degree: Ph.D.
Supervisor: Raudaskoski, M.
Institution: Dept. of Biosciences, University of Helsinki, Finland
The thesis can be downloaded from the address: http://ethesis.helsinki.fi/julkaisut/mat/bioti/vk/tarkka/
Year: 2001
E-mail: mika.tarkka@uni-tuebingen.de
SUMMARY: The development of pine root system and an ecologically important relationship between pine roots and fungal mycelium, ectomycorrhiza, were investigated at the molecular level. For the first time, developmentally regulated genes and proteins in Scots pine short roots and ectomycorrhiza with Suillus bovinus were identified. The protein patterns of different Scots pine root types were analysed by two-dimensional gel electrophoresis. The production of five proteins was found to be upregulated and the production of two proteins repressed during short root formation. In addition a single ectomycorrhiza-related polypeptide was detected. Amino acid sequencing and mass spectrometry were used to identify acidic short root-specific polypeptides as class III secretory peroxidases, which represent post-translationally modified forms of the same gene product. The corresponding cDNA, Psyp1 and two similar cDNA fragments probably encoding other members of Psyp1 gene family were isolated by reverse transcription-coupled polymerase chain reaction. The expression of Psyp1 is highest in short roots and down regulated during ectomycorrhiza formation. The function of the peroxidases may be related to the reduction of short root elongation, a specific feature of short root development. To further understand short root morphogenesis A- and B-type cyclin fragments were isolated from short roots and ectomycorrhiza. Furthermore, a change in a-tubulin production during short root formation and two a-tubulin proteins with ectomycorrhiza-specific production pattern were detected. Novel a-tubulin isotypes may be involved in structural rearrangements of microtubule cytoskeleton needed for differential cell wall synthesis and nutrient import and export in ectomycorrhiza. The fungal actin or tubulin protein production seemed not to be affected by ectomycorrhiza formation. In contrast to the single actin gene found in filamentous ascomycetes, two actin cDNAs were isolated from the cDNA library made from vegetative hyphae of Suillus bovinus and saprophytic Schizophyllum commune, both homobasidiomycetes. Northern hybridisation analysis showed that the actin genes from both fungi have different levels of expression, but no change in the expression pattern of S. bovinus actins was observed between vegetative and symbiotic hyphae. The cDNAs encoding universal regulators of actin cytoskeleton in eukaryotes, Cdc42 and Rac were also isolated from Suillus bovinus. They are expressed in vegetative hyphae and ectomycorrhiza. SbCdc42p was localized by IIF microscopy in vegetative hyphae and ectomycorrhiza, and its localisation pattern followed closely to that of the actin cytoskeleton. These results suggest that the small GTPases Cdc42 and Rac probably act in a similar manner in Suillus bovinus hyphae as in other eukaryotes and regulate the fungal morphogenesis at ectomycorrhiza formation through reorganisation of the actin cytoskeleton. The identified developmentally regulated genes and proteins will form a base for future work on ectomycorrhiza morphogenesis. The first isolated gene with short root-related expression pattern, Psyp1, will be used to reveal specific features of cell wall structure during root development and ectomycorrhiza formation. The changes in plant a-tubulin patterns and the presence of fungal Cdc42 and Rac in ectomycorrhiza emphasize the fundamental role of cytoskeleton in the establishment of plant-fungus interaction. In future, mutational analysis of the small GTPase cDNAs will be used to verify their role in the development of symbiotic hyphae.

 

 
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