| Autor: |
Sabry, Sami R., Saleh, Saleh A., Batchelor, Caroline A., Jones, June, Jotham, Joan, Webster, Gordon, Kothari, Shanker L., Davey, Michael R., Cocking, Edward C. |
| Zdroj: |
Proceedings B: Biological Sciences; March 1997, Vol. 264 Issue: 1380 p341-346, 6p |
| Abstrakt: |
Nitrogen fixing nodules are formed on the roots and stems of the tropical legume Sesbania rostrataby Azorhizobium caulinodansas a result of crack entry invasion of emerging lateral roots. Advantage was taken of this invasion capability of A. caulinodansto determine whether inoculation of the non–legume wheat with A. caulinodanswould result in the endophytic establishment of azorhizobia within wheat roots. Advantage was also taken of the oxygen tolerance of the nitrogenase of free–living azorhizobia to assess the extent to which the endophytic establishment of azorhizobia in wheat roots would provide a niche for nitrogen fixation of benefit to the plant. Wheat was inoculated with A. caulinodansand grown in pots under controlled conditions, without added growth reglators and without addition of fixed nitrogen. Microscopic examination of the short lateral roots of inocluated wheat showed invasion of azorhizobia between cells of the cortex, within the xylem and the root meristem Acetylene reduction assays combined with analysis of tissue nitrogen levels indicated the likelihood that colonization led to nitrogenase activity. Inoculated wheat showed significant increases in dry weight and nitrogen content as compared with uninoculated controls. We discuss the extent to which this nitrogen fixation is likely to involve symbiotic nitrogen fixation, and we indicate the need for field trials to determine the extent to which inolculation of wheat with A. caulinodanswill reduce the requirement for inputs of nitrogenous fertilizers. |
| Databáze: |
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