Symbiosome-like intracellular colonization of cereals and other crop plants by nitrogen-fixing bacteria for reduced inpu

It has been forecast that the challenge of meeting increased food demand and protecting environmental quality will be won or lost in maize, rice and wheat cropping systems,and that the problem of environmental nitrogen enrichment is most likely to be solved by substituting synthetic nitrogen fertilizers by the creation of cereal crops that are able to fix nitrogen symbiotically as legumes do. In legumes, rhizobia present intraceliularly in membrane-bound vesicular compartments in the cytoplasm of nodule cells fix nitrogen endosymbiotically. Within these symbiosomes, membrane-bound vesicular compartments, rhizobia are supplied with energy derived from plant photosynthates and in return supply the plant with biologically fixed nitrogen, usually as ammonia. This minimizes or eliminates the need for inputs of synthetic nitrogen fertilizers. Recently we have demonstrated, using novel inoculation conditions with very low numbers of bacteria, that cells of root meristems of maize, rice, wheat and other major non-legume crops, such as oilseed rape and tomato, can be intracellularly colonized by the non-rhizobial, non-nodulating, nitrogen fixing bacterium, Gluconacetobacter diazotrophicus that naturally occurs in sugarcane. G. diazotrophicus expressing nitrogen fixing (nifH) genes is present in symbiosome-like compartments in the cytoplasm of cells of the root meristems of the target cereals and non-legume crop species, somewhat similar to the intracellular symbiosome colonization of legume nodule cells by rhizobia. To obtain an indication of the likelihood of adequate growth and yield, of maize for example, with reduced inputs of synthetic nitrogen fertilizers,we are currently determining the extent to which nitrogen fixation, as assessed using various methods, is correlated with the extent of systemic intracellular colonization by G. diazotrophicus,with minimal or zero inputs.

作 者： Edward C. Cocking Philip J. Stone Michael R. Davey   作者單位： Edward C. Cocking(Centre for Crop Nitrogen Fixation, School of Biology, University of Nottingham, University Park, Nottingham NG7 2RD, U.K.;Plant Sciences Division, School of Biosciences, University of Nottingham, Sutton Bonington, Loughborough LE12 5RD, U.K.)

Philip J. Stone(Centre for Crop Nitrogen Fixation, School of Biology, University of Nottingham, University Park, Nottingham NG7 2RD, U.K.)

Michael R. Davey(Plant Sciences Division, School of Biosciences, University of Nottingham, Sutton Bonington, Loughborough LE12 5RD, U.K.) 

刊 名： 中國科學C輯（英文版）  SCI 英文刊名： SCIENCE IN CHINA SERIES C (LIFE SCIENCES)  年，卷(期)： 2005 48(z2)  分類號： P5  關鍵詞： cereals   endosymbiotic nitrogen fixation   Gluconacetobacter diazotrophicus   intracellular colonization   legumes   synthetic nitrogen fertilizers