Arbuscular Mycorrhizal Fungi and Rhizospheric Bacteria Diversity Along an Altitudinal Gradient in South American Puna Grassland

Abstract

Rhizospheric soil samples were taken from Puna native grasses along an altitudinal gradient. Biodiversity of arbuscular mycorrhizal fungi (AMF) and associated bacteria was analyzed considering altitude and grasses photosynthetic pathways (metabolic type C3, C4). Cultivation-dependent approaches were applied to obtain further information about the phylogeny of the dominating cultivable aerobic-heterotrophic bacteria communities present in rhizospheric soil samples. In average, the bacterial count ranged between 1.30 x 10(2) and 8.66 x 10(4) CFU g(-1) of dry weight of soil. Individual bacterial colonies of aerobic heterotrophic bacteria grown on R2A medium were morphologically grouped and identified as typical soil bacteria belonging to the genera Bacillus, Pseudomonas, and Arthrobacter. Ten AMF taxa were found: Acaulospora sp., A. laevis, A. spinosa, Gigaspora sp., Gi. ramisporophora, Glomus sp., Gl. aggregatum, Gl. ambisporum, Gl. sinuosum, and Scutellospora biornata. AMF diversity decreased with altitude.

Occurrence of arbuscular mycorrhizal fungi in high altitude sites of the Patagonian Altoandina region in Nahuel Huapi National Park (Argentina)

“…For example, spore abundance has been found to decrease with increasing elevation (Gai et al 2012) but also to pass through a maximum at an intermediate altitude (Li et al 2014;Coutinho et al 2015). AMF species richness furthermore has been reported as not affected (Li et al 2014) or decreasing (Lugo et al 2008;Gai et al 2012) with increased elevation or has been observed to peak at intermediate altitudes in an altitude gradient (Coutinho et al 2015). In contrast, the present study has indicated no correlation between AMF spore number and species richness with increasing altitude (Fig.…”

“…We disagree with the conclusion of Gai et al (2012) that a general pattern of AMF diversity and abundance over gradients in elevation can be detected worldwide. Our results along with recently published studies (Li et al 2014;Coutinho et al 2015) contrast with the patterns found by others (Lugo et al 2008;Schmidt et al 2008), thus suggesting that the variation in spore abundance and species richness over altitude gradients is, in fact, site-dependent and that variable conditions among those common to mountain environments -e. g., low temperatures, rainfall and moisture regimes, and frostinginfluence the abundance and richness of AMFs in different ways.…”

“…Previous investigations have indicated that plants occurring in the high Andes of Peru at altitudes of up to 5,391 m (Schmidt et al 2008) and in the Bolivian Andes at heights between 3,700 and 4,000 m are associated with AMF and dark septate endophytes. The species richness of AMF in high-altitude environments has also been reported (Lugo et al 2008;Oehl et al 2011a;Oehl & Koerner 2014) and new resident species described (Oehl et al 2012;Palenzuela et al 2014).…”

“…In addition|, 42 species from 11 genera were registered from the rupestrian fields in over five different habitat types ranging from 1,121 to 1,192 m of altitude in southeastern Brazil (Carvalho et al 2012). In Argentina, Lugo et al (2008) detected 10 species and 4 genera over a transect of altitudes ranging from 3,320 to 3,870 m.…”

Arbuscular mycorrhizal colonization and growth of Eremanthus incanus Less. in a highland field

“…Throughout this paper, we used the recent revision of Scutellospora by Oehl et al (2008) since it is more practical for spore identification. Lugo et al (2008) also found ten AMF species in the Puna highlands (Argentina), and notably two species (A. spinosa and D. biornata) were in common.…”