| Popis: |
The establishment of an endosymbiosis is the result of a complicated series of interactions for which D.C. Smith (1981) postulated a scheme of four stages: a contact, including events leading to contact, b incorporation into host matrix, c integration into regulatory mechanisms and d development of nutrient flows between (endo) symbiont and host. All stages may contain specific interactions which are only possible between homologous partners. However, if such specific interactions, which contain an element of recognition, are part of an essential step, their failure will prohibit all further stages. This failure will be most dramatic if it occurs early in the total sequence of interactions. These interactions form a very subtle, intricate pattern, for a main part operating at a subcellular level. This makes their analysis extremely difficult. Much information may be derived from comparisons with the deviations in the normal development, when less compatible combinations are studied. The progress in the microbial genetics of Rhizobium has markedly improved possibilities for such comparisons and enabled a further analysis of the interactions during infection and nodulation. |
