Responses of soil bacterial and fungal communities to extreme desiccation and rewetting
Responses of soil bacterial and fungal communities to extreme desiccation and rewetting
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DOI：
10.1038/ismej.2013.104
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发表时间：
2013-11-01
期刊：
影响因子：
11
通讯作者：
Firestone, Mary K.
中科院分区：
文献类型：
--
作者：
Barnard, Romain L.;Osborne, Catherine A.;Firestone, Mary K.
微生物对夏季干燥的响应反映了适应策略，为再湿润时降雨引起的土壤二氧化碳脉冲（生态系统碳收支的重要组成部分）奠定了基础。在加利福尼亚的三片一年生草地上，对当前（基于dna）和潜在活跃（基于rna）的土壤细菌和真菌群落进行了一个夏季的跟踪研究，并对完整土壤核心的受控再湿润进行了响应。对细菌（16S）和真菌（28S）系统发育标记基因的RNA和DNA进行测序，并测定这些基因和转录物的丰度。虽然不同地点的细菌群落组成不同，但所有地点都有相似的当前和潜在活跃的细菌群落对干干和湿化的响应模式。相比之下，真菌群落在不同地点之间没有明显差异，并且在很大程度上不受干燥影响，表现出明显的抗干燥性。随着夏季干衣的进行，潜在的活跃细菌群落发生了显著变化，然后在几个小时内恢复到干衣前的成分，显示出惊人的弹性。重新润湿后，细菌rpoB基因的转录本拷贝数持续增加，反映了快速的活性恢复。酸性菌门和放线菌门是目前最丰富且具有潜在活性的门，相对丰度变化最大。放线菌（Acidobacteria）对干干的相对增加和酸杆菌（Acidobacteria）的相对减少，以及对再湿润的相反反应反映了一种差异反应，这种反应在门水平上是保守的，在不同的位点上是一致的。这些与干燥相关的细菌生命策略的对比表明，降水模式的预测变化可能通过不同地影响微生物群落的活动模式来影响土壤养分和碳循环。
The microbial response to summer desiccation reflects adaptation strategies, setting the stage for a large rainfall-induced soil CO2 pulse upon rewetting, an important component of the ecosystem carbon budget. In three California annual grasslands, the present (DNA-based) and potentially active (RNA-based) soil bacterial and fungal communities were tracked over a summer season and in response to controlled rewetting of intact soil cores. Phylogenetic marker genes for bacterial (16S) and fungal (28S) RNA and DNA were sequenced, and the abundances of these genes and transcripts were measured. Although bacterial community composition differed among sites, all sites shared a similar response pattern of the present and potentially active bacterial community to dry-down and wet-up. In contrast, the fungal community was not detectably different among sites, and was largely unaffected by dry-down, showing marked resistance to dessication. The potentially active bacterial community changed significantly as summer dry-down progressed, then returned to pre-dry-down composition within several hours of rewetting, displaying spectacular resilience. Upon rewetting, transcript copies of bacterial rpoB genes increased consistently, reflecting rapid activity resumption. Acidobacteria and Actinobacteria were the most abundant phyla present and potentially active, and showed the largest changes in relative abundance. The relative increase (Actinobacteria) and decrease (Acidobacteria) with dry-down, and the reverse responses to rewetting reflected a differential response, which was conserved at the phylum level and consistent across sites. These contrasting desiccation-related bacterial life-strategies suggest that predicted changes in precipitation patterns may affect soil nutrient and carbon cycling by differentially impacting activity patterns of microbial communities.