ARS | Publication request: TRACKING METABOLISM AND IMAGING TRANSPORT IN ARBUSCULAR MYCORRHIZAL FUNGI

Submitted to: Plant and Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 27, 2002
Publication Date: N/A

Interpretive Summary: Under the Low Input Sustainable Agricultural (LISA) program, new , more efficient, methods of growing food crops with lower inputs of fertilizers and pesticides are presently being evaluated. One important means for achieving this goal is through the development of a plant/microbe symbiotic system known as arbuscular mycorrhizas (AM), whereby a low concentration of fwidely dispersed nutrients can be efficiently delivered from the soil to the growing plant. In addition the association of such microorganisms or fungi impart disease resistance to the plant making the need for pesticide application considerably lower. Ideally, one would want to inoculate fields with such beneficial organisms ("biofertilizers") to facilitate the LISA approach to food production, however, since these organisms are presently obligate symbionts they can only be grown in association with the host plant. This limits our ability to make large quantities of pure cultures of these fungi needed for field inoculation. In this study we have learned how lipids are transported from the host plant to the fungal AM partner. These lipids were found to be the critical carbon nutrient for the fungus. Using this information we will now alter the composition of the nutrient supplied to the free living fungus in order to facilitate the completion of its life cycle.

Technical Abstract: In the last few years the application of modern techniques to the study of arbuscular mycorrhizas has greatly increased our understanding of the mechanisms underlying carbon metabolism in these mutualistic symbioses. Arbuscular mycorrhizal monoxenic cultures, nuclear magnetic resonance spectroscopy together with isotopic labeling, and analyses of expressed sequence tags (ESTs)have shed light on the metabolic processes taking plac in these interactions, particularly in the case of the mycobiont. More recently,in vivo multiphoton microscopy has provided us of some new insight in the allocation and translocation processes which play crucial roles in the distribution of host plant-derived C throughout the fungal colony. In this study we highlight recent advances in these fields, as well as raise questions and postulate regulatory mechanisms for C metabolism and translocation within the arbuscular mycorrhizal fungal colony.