The arbuscular mycorrhizal fungi of Lotus glaber.

ANALÍA SANNAZZARO; ANA MENÉNDEZ; EDGARDO ALBERTÓ Y OSCAR A RUIZ

Chascomús. Buenos Aires. Argentina

Taller; TALLER INTERDISCIPLINARIO SOBRE ASPECTOS GENETICOS, MOLECULARES Y FISIOECOLOGICOS DEL LOTUS SPP. Y SUS SIMBIONTES.; 2004

IIB-INTECh. Chascomús. Argentina

We intended to study the composition and structure of arbuscular mycorrhizal (AM) fungal community associated with Lotus glaber in sodic soils of the Salado River basin. Roots were cleared, stained with Trypan blue and the amount of intraradical mycorrhizal structures estimated by the slide method. Spores were identified after isolation by wet sieving and decanting. The chemical analysis of rhizospheric soil was performed. Spores of eighteen different AM species were detected. Glomus geosporum, the most frequently isolated AM fungus, was also the dominant one. Shannon-Wiener diversity index varied between 0.65 and 1.65. Morphological types of AM fungi associated with L. glaber were also studied. At least eight colonization patterns (IP) of AM fungi in roots of L. glaber were observed. Arum- and Paris-types of infection were found in the same plant species. This result supports the idea that the morphology of AM is not solely under plant control, but is also influenced by fungal identity. One IP presumably corresponding to G. intraradices and a second one possibly assignable to G. tenue were the most commonly found. Additionally, DNA from the root samples was isolated and intergenic DNA sequences from the AM fungi were amplified through a nested PCR with taxon-specific primers. Problems in cloning and sequencing caused that only two fragments had been successfully sequenced. Sequencing of these clones and the comparisons with the data in the Genbank revealed that the amplified fragments possess a high homology percentage with sequences from G. intraradices. Our findings reinforce previous suggestions that G. geosporum and G. intraradices are well adapted to sodic-saline conditions and would play a role in the resistance of L. glaber to these soils.