Microbial community biogeographic patterns in the rhizosphere of two Brazilian semi-arid leguminous trees

Abstract

Arid environments are regular and well distributed over all continents and display drought characteristics whether full-time or seasonal. This study aims to characterize how the microbial communities of the rhizosphere of two leguminous trees from the Brazilian semi-arid biome the Caatinga are geographically and seasonally shaped, as well as the factors driving this variation. With that purpose, the soil rhizosphere from two leguminous trees (Mimosa tenuiflora and Piptadenia stipulacea (Benth.) Ducke) were sampled in two different seasons: rainy and drought at five different sites. Assessment of bacterial and archaeal communities occurred by T-RFLP analysis of 16S rRNA and archaeal amoA genes. By these means, it was observed that the seasons (wet and dry periods) are the factors that most influence the composition of the microbial community from both analyzed plants, except for the results obtained from the CCA applied to Archaeas. Furthermore, soil physical-chemical factors also had a significant influence on the community and indicated a geographical pattern of the bacterial community. It was not possible to observe significant modifications in the composition in relation to the plant species. We have seen that soil characteristics and rainfall were the factors that most influenced the microbial composition. Also, the bacterial community had a significant correlation with soil characteristics that indicates that these rhizosphere communities might be selected by environmental characteristics. Furthermore, the data suggest that climate plays a key role in structuring the microbial community of this biome.

Functional congruence of rhizosphere microbial communities associated to leguminous tree from Brazilian semiarid region

“…Although there has not been a significant effect of environmental variables over the community structure through CCA, soil variability might have influenced this variation, since some of these characteristics (i.e. temperature, moisture content, nutrient availability) have been pointed out as the main drivers of soil bacterial communities variability (Fierer et al ., ; Pasternak et al ., ) as observed for the diversity in the Caatinga based on gene markers (SSU and amo A gene) (Kavamura et al ., ; Lançoni et al ., ).…”

“…This study represents one of the first analyses of Brazilian semiarid metagenomes conducted to date with over 250 Mb of metagenomic data obtained from six different libraries. Nevertheless, we could detect some patterns in the datasets that highlight the same trend in the shifts of communities when compared with studies of the same biome (Kavamura et al ., ; Lançoni et al ., ). Furthermore, microbial communities found in semiarid soils are known to display two different life moments, one of high activity (Barnard et al ., ) and increased diversity characterized by the presence of Proteobacteria due to the presence of rain, and another one of lower activity and abundance of Actinobacteria, in a strategy of preparedness.…”

“…Samples were kept in plastic bags and stored at room temperature until processing. Physical and chemical analyses were performed in each sample and were published previously (Lançoni et al ., ). According to this study, sites 1 and 2 did not present many significant differences in the analysed characteristics, while site 3 did, which makes site 1 and 2 much more similar between them than with site 3.…”

Plant compartment and biogeography affect microbiome composition in cultivated and native Agave species

“…Previous studies investigating the microbial communities associated with diverse plant hosts have demonstrated that sample type (plant compartment), host species, geographic location, and season are all capable of influencing community composition, although the extent to which each plays a role has varied from study to study (DeAngelis et al, 2008;Lundberg et al, 2012;Lanc ßoni et al, 2013;Peiffer et al, 2013;Mendes et al, 2014;Edwards et al, 2015;Zarraonaindia et al, 2015). Most previous studies have focused on prokaryotic communities, providing limited insights into the forces shaping plant-associated fungal communities.…”

Archaea in Natural and Impacted Brazilian Environments

“…However, it was not possible to detect any significant difference in the archaeal community for the two plants, neither in relation to the different points nor in relation to seasons [116]. …”