The arbuscular mycorrhizal fungi of Lotus glaber.

ANALÍA I. SANNAZZARO, ANA B. MENÉNDEZ, EDGARDO ALBERTÓ AND OSCAR A. RUIZ

Chascomús, Argentina

Taller; Taller interdisciplinario sobre aspectos genéticos, moleculares y ecofisiológicos del Lotus spp. y sus simbiontes.; 2005

INTECH - CONICET

We intended to study the composition and structure of arbuscular mycorrhizal (AM) fungalcommunity associated with Lotus glaber in sodic soils of the Salado River basin.Roots were cleared, stained with Trypan blue and the amount of intraradical mycorrhizalstructures estimated by the slide method. Spores were identified after isolation by wetsieving and decanting. The chemical analysis of rhizospheric soil was performed.Spores of eighteen different AM species were detected. Glomus geosporum, the mostfrequently isolated AM fungus, was also the dominant one. Shannon-Wiener diversity indexvaried between 0.65 and 1.65.Morphological types of AM fungi associated with L. glaber were also studied. At least eightcolonization patterns (IP) of AM fungi in roots of L. glaber were observed. Arum- andParis-types of infection were found in the same plant species. This result supports the ideathat the morphology of AM is not solely under plant control, but is also influenced by fungalidentity. One IP presumably corresponding to G. intraradices and a second one possiblyassignable to G. tenue were the most commonly found.Additionally, DNA from the root samples was isolated and intergenic DNA sequences fromthe AM fungi were amplified through a nested PCR with taxon-specific primers. Problemsin cloning and sequencing caused that only two fragments have been successfullysequenced. Sequencing of these clones and the comparisons with the data in the Genebankrevealed that the amplified fragments possess a high homology percentage with sequencesfrom G. intraradicesOur findings reinforce previous suggestions that G. geosporum and G. intraradices are welladapted to sodic-saline conditions and would play a role in the resistance of L. glaber tothese soils.