Effect of Drought Stress and Developmental Stages on Microbial Community Structure and Diversity in Peanut Rhizosphere Soil

Abstract

Background: Peanut (Arachis hypogaea L.), an important oilseed and food legume, is widely cultivated in the semi-arid tropics. Drought is the major stress in this region which limits productivity. Microbial communities in the rhizosphere are of special importance to stress tolerance. However, relatively little is known about the relationship between drought and microbial communities in peanuts. Method: In this study, deep sequencing of the V3-V4 region of the 16S rRNA gene was performed to characterize the microbial community structure of drought-treated and untreated peanuts. Results: Taxonomic analysis showed that Actinobacteria, Proteobacteria, Saccharibacteria, Chloroflexi, Acidobacteria and Cyanobacteria were the dominant phyla in the peanut rhizosphere. Comparisons of microbial community structure of peanuts revealed that the relative abundance of Actinobacteria and Acidobacteria dramatically increased in the seedling and podding stages in drought-treated soil, while that of Cyanobacteria and Gemmatimonadetes increased in the flowering stage in drought-treated rhizospheres. Metagenomic profiling indicated that sequences related to metabolism, signaling transduction, defense mechanism and basic vital activity were enriched in the drought-treated rhizosphere, which may have implications for plant survival and drought tolerance. Conclusion: This microbial communities study will form the foundation for future improvement of drought tolerance of peanuts via modification of the soil microbes.

Influence of Salt Stress on Growth of Spermosphere Bacterial Communities in Different Peanut (Arachis hypogaea L.) Cultivars

“…Proteobacteria, Actinobacteria, and Firmicutes were the mutually dominant bacterial phyla of peanuts and the above plants, indicating that they are the most common dominant bacterial phyla in plant spermosphere soils. In our recent data, Proteobacteria and Actinobacteria dominated in rhizosphere soil of peanut, which suggested that Proteobacteria and Actinobacteria are the two most abundant bacteria in the soil around peanut [1]. The biological function of the two phyla in peanut soils needs further research.…”

“…Over the past decade, various studies have emerged that implicate members of the rhizosphere microbial communities in enhancing plants stress tolerance by activating stress response or providing a buffer zone for plants against stress [54][55][56]. In the previous paper, the defense mechanism in the microbial community of drought-treated peanut rhizosphere soils was significantly higher than that of the controlled soil [1]. Similar to this, the defense mechanism was also predicted as being higher in salt-treated peanut spermosphere soils in this study ( Figure 6A).…”

“…Thus, the more vigorous xenobiotics biodegradation and metabolism in salt-treated spermosphere soils may be implicated in salt stress tolerance ( Figure 6B). Moreover, stress response processes (replication and repair and signaling molecules and interaction) predicted higher in salt-treated spermosphere soils, which can confer high tolerance levels to stress and toxic compounds [1]. Over the past decade, various studies have emerged that implicate members of the rhizosphere microbial communities in enhancing plants stress tolerance by activating stress response or providing a buffer zone for plants against stress [54][55][56].…”

“…Then, we placed them at the greenhouse under the conditions of 28 • C and approximately 16/8 h light/dark photoperiod. Subsequently, each transparent acrylic tank was irrigated with sterile ddH 2 O to keep the soil water content at 85% of field capacity by weighing, as was done in the previous study [1]. After 72 h (when most of the radicles can emerge), seeds and soil samples were collected and placed on the sterile silver paper [21], and the germination rate of the two peanut cultivars are shown in Figure S5.…”

“…Peanut or groundnut (Arachis hypogaea L.), an important nutritious food and cash crop, is consumed both as oilseed and livestock fodder, forming an important revenue source for farmers [1,2]. As a moderately salt-sensitive species, cultivation of peanuts was attempted in low-salinity fields in China to gain more crop production [3,4].…”