الصفحة 1
الصفحة 1
Microbial Root Endophytes
Plant roots may not only be colonized by mycorrhizal fungi, but also by a myriad of bacterial and fungal root endophytes that are usually not considered by the investigators of classic symbioses. This is the first book dedicated to the interactions of non-mycorrhizal microbial endophytes with plant roots. The phenotypes of these interactions can be extremely plastic, depending on environmental factors, nutritional status, genetic disposition and developmental stages of the two partners. The book deals with diversity, life history strategies, interactions, applications in agriculture and forestry, methods for isolation, cultivation, and both conventional and molecular methods for identification and detection of these endophytes. The comprehensive reviews demonstrate the high diversity of interactions and will provoke further studies to better understand the mechanisms which determine whether a plant-microbial interaction remains asymptomatic, leads to disease or to a mutualistic interaction.
Microbial Activity in the Rhizosphere
The rhizosphere is a very complex environment in which the effects of the plant on soil microorganisms and the effects of the microorganisms on the plant are interacting and are interdependent. Plant root exudates and breakdown products attract microbes and feed them and, in turn, the plants often benefit from the microbes. Interactions among microorganisms and plant roots are essential for nutritional requirements of the plant. Plant growth, development and productivity are largely dependent on the soil environment in the root region rhizosphere. The new techniques of studying the rhizosphere enables us to get a much better understanding of the dynamics of the rhizosphere population, such rhizosphere studies being of interest to agriculturists, soilbiologists, chemists, microbiologists and molecular biologists. The rhizosphere microbes in?uence the root environment in several ways. They may change the oxidation-reduction potential, influence the availability of moisture and nutrients, produce growth inhibiting or growth promoting substances in the form of exudates, provide competition and possibly induce many other effects. My corrhizal associations are beneficial in mineral uptake and in increasing root surface area for effective ion absorption. Antagonism, ompetition and synergism in soil and the rhizoplane (rhizosphere) are the most important microbial interactions to consider in the study of rhizosphere biology. With the growing information on the production of growth regulators, competitiveness of the microbes in the rhizosphere, microsymbionts, and other factors, their effect upon plant growth will become more evident. Experiments on the introduction of microbes or their products in the rhizosphere will help to improve our understandingofthebiologyoftherhizosphere.
Medicinal roots and tubers for pharmaceutical and commercial applications
The root and tuber are vital parts of medicinal plants providing mechanical support, producing critical growth regulators, and storing food. Bioactive compounds obtained from plant roots and tubers demonstrate health benefits presenting antioxidative, antimicrobial, hypoglycaemic, hypocholesterolaemic, and immunomodulatory properties. Roots of many medicinal plants have been used for the treatment of disease and formulation of drugs, and they are also known for their commercial value, being used as an ingredient in the pharmaceutical and cosmetic industries.
Associative and endophytic nitrogen-fixing bacteria and cyanobacterial associations
Associative and Endophytic Nitrogen-fixing Bacteria and Cyanobacterial Associations This book is part of the seven-volume series that was launched a few years ago with the ambitious objectives of reviewing the field of nitrogen fixation from its earliest beginnings through the millennium change and of consolidating the relevant information - from fundamental to agricultural and environmental aspects – all in one place. Volume 5 covers the biology of bacteria that associate with n- leguminous plants. The subject matter includes a wide range of associations; it covers the bacterial species that associate either with the surface or within the tissues of grasses (often referred as plant growth-promoting rhizobacteria) and also the symbiotic associations that cyanobacteria form with fungi, algae, and both lower and higher plants. This volume does not deal with the Frankia-actinorhizal plant associations, which is the topic of Volume 6
