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ARS Home » Plains Area » Lubbock, Texas » Cropping Systems Research Laboratory » Wind Erosion and Water Conservation Research » Research » Publications at this Location » Publication #298497
Title: Predominant bacterial and fungal assemblages in agricultural soils during a record drought/heat wave and linkages to enzyme activities of biogeochemical cycling

Author
item Acosta-Martinez, Veronica
item Cotton, Jon
item GARDNER, TERRENCE - North Carolina State University
item MOORE-KUCERA, JENNIFER - Texas Tech University
item ZAK, JOHN - Texas Tech University
item WESTER, DAVID - Texas A&M University
item COX, STEPHEN - Research And Testing Laboratories, Llc

Submitted to: Applied Soil Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/12/2014
Publication Date: 12/1/2014
Citation: Acosta Martinez, V., Cotton, J.E., Gardner, T., Moore-Kucera, J., Zak, J., Wester, D., Cox, S. 2014. Predominant bacterial and fungal assemblages in agricultural soils during a record drought/heat wave and linkages to enzyme activities of biogeochemical cycling. Applied Soil Ecology. 84:69-82.

Interpretive Summary: Extreme weather events may have profound impacts on microbial community composition and function. During November 2010 to August 2011, the Southern High Plains (SHP) of Texas, U.S., received only 39.6 mm of precipitation (vs. the historical average of 373 mm) and experienced the hottest summer since record keeping began in 1911. Scientists from the SHP region assessed the microbial diversity of soil samples collected in July 2011 during the peak of the drought/heat wave and in March 2012 when the drought index and temperatures where reduced. Samples were collected under two different dryland cropping histories: monoculture cotton and an annual rotation of cotton and foxtail millet or sorghum. The study accomplished: (1) identification of predominant bacteria and fungi taxa (i.e., phyla, order and species) associated to the drought and intense heat wave event; (2) identification of distinct communities in the rotation vs. monoculture despite extreme drought/heat wave conditions; and (3) identification of distinct assemblages of fungal and bacterial taxa correlated with C, P or S cycling enzyme activities in July 2011 (without sharing of taxa among enzymes). This study will aid to increase our understanding of the response and recovery of microbial communities under agroecosystems to major drought and intense heat waves in this and similar regions.

Technical Abstract: Extreme weather events may have profound impacts on microbial community composition and functionality. During November 2010 to August 2011, the Southern High Plains (SHP) of Texas, U.S., received only 39.6 mm of precipitation (vs. the historical average of 373 mm) and experienced the hottest summer since record keeping began in 1911. The objective of this study was to assess microbial diversity of soil samples collected in July 2011 during the peak of the drought/heat wave and in March 2012 when the drought index and temperatures where reduced. Samples were collected under two different dryland cropping histories: monoculture cotton (Gossypium hirsutum L.) and an annual rotation of cotton and foxtail millet (Setaria italica) or sorghum (Sorghum bicolor L. Moench). Bacterial and fungal diversity was assessed by pyrosequencing on the 16S rRNA gene and the Internal Transcribed Spacer 1 (ITS1), respectively. The July samples were characterized by lower relative abundance of Acidobacteria, Verrucomicrobia and Gemmatimonadetes, and greater relative abundance of Proteobacteria, Chloroflexi, Actinobacteria and Bacteroidetes than March 2012 samples. Further grouping of pyrosequencing data revealed approximately equal relative proportions of Gram + and Gram - bacteria in July 2011 while G- bacteria predominated in March 2012. The relative abundance of members of the Dothideomycetes and Tremellomycetes orders were approximately two times greater in July 2011 than in March 2012. Sordariomycetes, Glomeromycetes and Ascomycota (class) were lower in July 2011 than in March 2012. In addition to the changes in microbial community composition due to the drought/ heat wave, the microbiome continued to be a fingerprint of cropping history despite extreme drought conditions (i.e., distinct communities in the rotation vs. monoculture). Distinct assemblages of fungal and bacterial taxa were significantly correlated with C, P or S cycling enzyme activities in July 2011 (without sharing of taxa among enzymes). These distinct microbial assemblages may aid in the recovery of agroecosystem function following a major drought and intense heat wave.