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Descripción
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| Rhizobia are Gram-?negative bacteria that can form structures called root nodules in symbiosis with legumes. These structures, allow the bacteria fixing atmospheric dinitrogen into ammonia, which can be used by the plant. At the same time, these bacteria receive carbon sources from the plant resulting in a symbiotic relationship. Secretion systems are nanostructures which have been identified in Gram-?negative bacteria that allow mainly the translocation of proteins. Six types of secretion systems have been identified named I to VI. Type III secretion system (T3SS) have been identified in several rhizobia. It allows the transfer of effector proteins called ?Nops?outside the bacteria or into eukaryotic cells which can affect symbiosis with legumes in a host specific manner. The aim of this work, is to analyse the T3SS in a Bradyrhizobium strain LmjC, isolated from Lupinus mariae-?josephae, an unique endemism found in alkaline soils in Eastern Spain. A knock-?out mutant was constructed in the rhcU gene encoding a structural component conserved in all T3SSs, in order to analyse its symbiotic phenotype with L. mariae-?josephae and L. angustifolius. The results with L. mariae-?josephae plants inoculated with the mutant showed an effective symbiosis, with nodules and nitrogenase activity similar to plants inoculated with the wild type strain LmjC. L. angustifolius inoculated with LmjC or with the rhcU mutant presented white no-? effective nodules . Therefore, these results indicate that rhcU does not play a role in the symbiotic process between L. mariae-?josephae and LmjC. | |
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Internacional
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Tipo de Tesis
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Master |
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Calificación
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Fecha
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