Bacterial community in the rhizosphere of the cactus species Mammillaria carnea during dry and rainy seasons assessed by deep sequencing
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Background and aims
The Tehuacán-Cuitcatlán reserve is an area of unique plant biodiversity mostly in the form of xerophytes, with exceptionally high numbers of rare and endemic species. This endemism results partly from the characteristics of the climate of this area, with two distinct seasons: rainy and dry seasons. Although rhizosphere communities must be critical in the function of this ecosystem, understanding the structure of these communities is currently limited. This is the first molecular study of the microbial diversity present in the rhizosphere of Mamillaria carnea.
Total DNA was obtained from soil and rhizosphere samples at three locations in the Tehuacán Cuicatlán Reserve, during dry and rainy seasons. Temperature gradient gel electrophoresisis (TGGE) fingerprinting, 16S rRNA gene libraries and pyrosequencing were used to investigate bacterial diversity in the rhizosphere of Mammillaria carnea and changes in the microbial community between seasons.
Deep sequencing data reveal a higher level of biodiversity in the dry season. Statistical analyses based on these data indicates that the composition of the bacterial community differed between both seasons affecting to members of the phyla Acidobacteria, Cyanobacteria, Gemmatimonadetes, Plantomycetes, Actinobacteria and Firmicutes. In addition, the depth of sequencing performed (>24,000 reads) enables detection of changes in the relative abundance of lower bacterial taxa (novel bacterial phylotypes) indicative of the increase of specific bacterial populations due to the season.
This study states the basis of the bacterial diversity in the rhizosphere of cacti in semi-arid environments and it is a sequence-based demonstration of community shifts in different seasons.
KeywordsMicrobial community Soil bacteria 16S rRNA analysis Mammillaria carnea Tehuacán Cuicatlán reserve 454-pyrosequencing
This work was supported by research projects BIO2003-02473, OAPN21/2007, BIO2008-00740 and CSD 2009-0006 of the Consolider-Ingenio 2010 program from the Ministerio de Ciencia e Innovación; P08-CVI-03549 from Consejería de Innovación, Ciencia y Empresa of Junta de Andalucía including ERDF (European Regional Development Fund); and the BBVA Foundation (BBVA BIOCON 04-084 Project). G.T.C. and A.J.F.G. were supported by CSIC predoctoral and FPU fellowships, respectively, from the Ministerio de Ciencia e Innovación. V.M. and J.F.A.G. were supported by the mentioned BBVA Project. We are grateful to J.I. Jiménez-Zurdo and A. Schüβler for critical reading of the manuscript.
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