CONSTITUTIVE OVEREXPRESSION OF A HETEROLOGOUS AGGLUTININ IN RHIZOBIUM ETLI INTERFERES N2 FIXATION IN PHASEOLUS VULGARIS.

MONGIARDINI, E.J.; AUSMEES, N.; PÉREZ GIMÉNEZ, J.; ALTHABEGOITI, M.J.; LÓPEZ GARCÍA, S.L.; QUELAS, J.I.; FRYKBERG, L.; LODEIRO, A.R.

Iguazú, Misiones

Congreso; XL Reunión Anual - SAIB; 2004

Sociedad Argentina de Investigación Bioquímica y Biología Molecular

 The agglutinin known as RapA1 from R. leguminosarum bv. trifolii was constitutively overexpressed in a multicopy plasmid under the control of plac promoter in this same species as well as in R. etli or R. tropici. By comparison with control strains carrying the plasmid vector without rapA1 insert we observed that although the host specificity did not change, only the R. etli strain overexpressing RapA1 constitutively was affected in nodulation. It produced less total nodules and at a lower rate than the wild-type with plasmid vector alone. Neither a truncated form of RapA1 lacking its C-terminal end nor the entire gene overexpressed under the control of its own promoter had any effect. Forty day-old plants –at the beginning of flowering– maintained with N-free solution were dwarf and yellow when inoculated with the constitutively overexpressing strain, as uninoculated controls. By difference, the controls inoculated with the wild-type with plasmid vector alone were green and healthy, pointing out that the constitutive overexpression of RapA1 interfered N2 fixation.