Identification Of A Small Heat Shock Protein Associated With A Ras Mediated Signaling Pathway In Ectomycorrhizal Symbiosis

Initiation, development, and establishment of a functional ectomycorrhiza involve a series of biochemical events mediated by a number of genes from the fungus as well as the host plant. We have identified a heat shock protein gene from Laccaria bicolor (Lbhsp) that appears to play a role in these events. The size and characteristics of Lbhsp suggest that it belongs to the family of small heat-shock proteins described in the literature. Nucleotide sequencing of an almost full length cDNA indicated that the Lbhsp mRNA is about 611 nucleotides long and codes for a single protein of ~ 17 kDa. Isolation and characterization of the Lbhsp gene showed that it was made up of three exons separated by two small introns. Southern analysis suggested that the L. bicolor genome contains at least two copies of the Lbhsp gene. Temporal expression analyses revealed that the gene is expressed within 4 to 12 hours after interaction with red pine roots. The yeast two-hybrid studies showed that the Lbhsp was closely associated with the ras gene (Lbras) described earlier. The data suggest that Lbhsp may play a supporting role in ras-mediated mycorrhizal signaling pathways during various stages of ectomycorrhizal development.

This book provides an overview of the latest advances concerning symbiotic relationships between plants and microbes, and their applications in plant productivity and agricultural sustainability. Symbiosis is a living phenomenon including dynamic variations in the genome, metabolism and signaling network, and adopting a multidirectional perspective on their interactions is required when studying symbiotic organisms. Although various plant-microbe symbiotic systems are covered in this book, it especially focuses on arbuscular mycorrhiza (AM) symbiosis and root nodule symbiosis, the two most prevalent systems. AM symbiosis involves the most extensive interaction between plants and microbes, in the context of phylogeny and ecology. As more than 90% of all known species of plants have the potential to form mycorrhizal associations, the productivity and species composition, as well as the diversity of natural ecosystems, are frequently dependent upon the presence and activity of mycorrhizas. In turn, root nodule symbiosis includes morphogenesis and is formed by communication between plants and nitrogen-fixing bacteria. The biotechnological application of plant–microbe symbiosis is expected to foster the production of agricultural and horticultural products while maintaining ecologically and economically sustainable production systems. Designed as a hands-on guide, this book offers an essential resource for researchers and students in the areas of agri-biotechnology, soil biology and fungal biology.

Recent years have seen tremendous progress in unraveling the molecular basis of different plant-microbe interactions. Knowledge has accumulated on the mecha nisms of the microbial infection of plants, which can lead to either disease or resistance. The mechanisms developed by plants to interact with microbes, whether viruses, bacteria, or fungi, involve events that can lead to symbiotic association or to disease or tumor formation. Cell death caused by pathogen infection has been of great interest for many years because of its association with plant resistance. There appear to be two types of plant cell death associated with pathogen infection, a rapid hypersensitive cell death localized at the site of infection during an incompatible interaction between a resistant plant and an avirulent pathogen, and a slow, normosensitive plant cell death that spreads beyond the site of infection during some compatible interactions involving a susceptible plant and a virulent, necrogenic pathogen. Plants possess a number of defense mechanisms against infection, such as (i) production of phytoalexin, (ii) formation of hydrolases, (iii) accumulation of hydroxyproline-rich glycoprotein and lignin deposition, (iv) production of pathogen-related proteins, (v) produc tion of oligosaccharides, jasmonic acid, and various other phenolic substances, and (vi) production of toxin-metabolizing enzymes. Based on these observations, insertion of a single suitable gene in a particular plant has yielded promising results in imparting resistance against specific infection or disease. It appears that a signal received after microbe infection triggers different signal transduction pathways.

Not only an invaluable reference to what is known about lichen bionts and their interactions but also a guide to future studies. Compares various aspects of lichen-forming bionts with those of other fungi, algae and cyanobacteria. Features in-depth descriptions of culture methods. Includes over 1000 references representing a selective sampling in such subjects as air pollution, photosynthesis and respiration.

Ectomycorrhizal fungi play multifunctional roles during symbioses with higher plants. They can serve as bioprotectors, biofertilizers, bioremediators and stress indicators. Further, they are the true “mycoindicators” of forest ecosystems, where an enormous diversity of ectomycorrhizal fungi can be found. Some ectomycorrhizal fungi also produce edible sporocarps, i.e., fruiting bodies, which are important for the food industry. Ectomycorrhizal fungi also produce various metal chelating molecules, which are of remarkable biotechnological significance and which also secrete useful secondary metabolites. Molecular approaches are required for the identification and differentiation of fungi forming symbioses with higher plants, while molecular tools are important to understand how genes are expressed during symbiosis with higher plants. Students, researchers and teachers of botany, mycology, microbiology, forestry, and biotechnology will find a valuable source of information in this Soil Biology volume.

This open access book, written by world experts in aquaponics and related technologies, provides the authoritative and comprehensive overview of the key aquaculture and hydroponic and other integrated systems, socio-economic and environmental aspects. Aquaponic systems, which combine aquaculture and vegetable food production offer alternative technology solutions for a world that is increasingly under stress through population growth, urbanisation, water shortages, land and soil degradation, environmental pollution, world hunger and climate change.