Nod-Factors in Symbiotic Development of Root Hairs

摘要: Generally, root hairs emerge at the apical end of some epidermal cells, and elongate by polar growth tip (Cormack 1962; see Chapters 1 to 3 this volume). Young, elongating are extensively colonized soil-borne micro-organisms. Intimate associations between dissimilar organisms common, especially in nutrient poor environments. Prevalent amongst these nitrogen-fixing symbioses which photosynthetic provide carbohydrates exchange for organic nitrogen exported diazotrophs. Soil bacteria genera Azorhizobium, Bradyrhizobium, Mesorhizobium, Rhizobium Sinorhizobium (collectively called rhizobia) enter roots (and occasionally adventitious-roots on stems) legumes (family Leguminosae), induce formation highly specialised organs, nodules. Rhizobia present nodules convert an endo-symbiotic form, bacteroids, dinitrogen is reduced ammonia. Bacteroids within contribute a disproportionately large portion fixed global pool.