Diversity of endophytic bacteria isolated from Yerba mate (Ilex paraguariensis) leaves and stems.

PÉREZ, MA LAURA; COLLAVINO, MÓNICA M.; GALDEANO, ERNESTINA; SANSBERRO, PEDRO A.; MROGINSKI, LUIS A

Mar del Plata

Congreso; VIII Congreso Argentino de Microbiología General (SAMIGE); 2012

SAMIGE

The term endophyte refers to microorganisms that produce internal or inconspicuous infections in which the infected tissue is at least transiently asymptomatic. Although the endophytic bacteria-host plant interaction is not yet completely understood, many isolates have been found that affect the host plant physiology whether promoting plant growth, producing antimicrobial compounds or inducing plant defense responses. To analyze the endophytic bacteria community associated to yerba mate plants, we made 6 surveys during 2 years (summer and autumn 2010; summer, autumn and winter 2011) in 3 yerba mate clones (SI-49, LM y G-18) from an experimental clonal field of Las Marías S.A. in Virasoro, Loma Tubonet. Young and adult branches were analyzed. Plant samples were first disinfected with 70% ethanol for 2 mins and 20% commercial bleach for 20 mins and rinsed with sterilized deionized water and then homogenized in PBS and grown in enriched TSA medium with 100g/L cycloheximide. Colonies of the predominant morphology were selected at random from each plate. A collection of 326 isolates was established and so far a sample of 183 isolates (56%) has been characterized by Rep-PCR (Repetitive Extragenic Palindromic Sequence PCR) using ERIC1R-ERIC2 primers. 80 different fingerprints were observed using an 80% identity cutoff to discern groups. Higher species richness (Chao 1 estimator) was observed in summer and autumn 2010 and winter 2011 samples, and lower in autumn 2011 surveys. One isolate representing each fingerprint pattern was identified by 16S rARN gene partial sequence analysis. These results associated the isolates with genus Curtobacterium, Herbiconiux, Leucobacter, Mycobacterium, Microbacterium, Aeromicrobium, Cellulosimicrobium, Kineococcus, Methylobacterium, Agrobacterium, Rhizobium, Roseomona, Bacillus, Paenibacillus, Staphylococcus, Sphingomonas, Brevundimonas. The dominant group corresponded to order Actinomycetales (59% of analyzed isolates) while the dominant genus were Curtobacterium and Microbacterium (44% ). The bacteria genus identified in yerba mate leaves and stems were different from those that had been previously isolated from yerba mate roots and rhizosphere.