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| DOI：10.13522/j.cnki.ggps.2019160 |
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| The Effects of Thermal Stress on Diversity of Rhizobacteria and Functional Genes of Rice Rhizosphere |
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QIU Husen, ZHEN Bo, ZHOU Xinguo
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1. Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences, Xinxiang 453002, China;2. National Agro-ecological System Observation and Research Station of Shangqiu,Chinese Academy of Agricultural Sciences, Shangqiu 476000, China
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| Abstract: |
| 【Objective】Rice is able to withstand thermal stress to some extent by regulating its physiological and biochemical processes. Since change to the plant metabolic process alerts the quality of carbon input to soil, thermal stress could shift the structure and functions of microbial communities in the rhizosphere. These in turn will change nutrients supply and resistance of the plant against pathogeneses due to the change in functional genes of soil microbes. Understanding the response of metabolic functions of rhizosphere microbes to environmental stress is hence important to improve soil ecosystem services and biogeochemical cycles.【Objective】The purpose of this paper is to elucidate the responsive change in expression of functional genes associated with physiological metabolic processes of rhizobacteria to thermal stress using high-throughput technique and functional prediction.【Method】The experiment was conducted in pots grown with rice. Thermal stress was deliberately introduced to the plant for seven days at the jointing stage. The bacterial flora analysis, gene annotation and function classification were performed in conjunction with the PICRUSt (Phylogenetic Information of Common by Construction of States) and the high-throughput sequencing. 【Result】Compared with the control, thermal stress enriched the relatively low abundant bacterial classes (such as Gemmatimonadetes, Planctomycetes, Latescibacteria, Spirochaetae, Microgenomates, and Candidatus_Berkelbacteria); it also increased the numbers and percentage of the positive link (bacteria-bacteria) between taxa. Most transcripts of the bacteria were derived from Proteobacteria, followed by Acidobacteria, Actinobacteria, and chlorobi. Based on the COG functional classification database, the main active genes in both control and thermal stress treatments were associated with metabolism, cellular processes and the signaling. Thermal stress increased relative abundance of the genes associated with cell motility, signal transduction, intracellular trafficking, secretion, vesicular transport, and biogenesis of cellular wall, membrane and envelope. In contrast, it reduced the relative abundance of genes associated with amino acid transport and metabolism, lipid transport and metabolism, secondary metabolites biosynthesis, transport and catabolism, and transcription. Thermal stress did not affect rhizobacteria flora, but increased bacterial Shannon diversity, strengthened the symbiotic relationship of bacterial flora, and significantly impacted expression of genes involved in cell growth and death, as well metabolism and protein synthesis. 【Conclusion】Thermal stress not only affects physiology of rice but also alters the structure of the microbe community in the rhizosphere and the relative abundances of the function genes. |
| Key words: therma stress; rice; rhizobacteria; physiological metabolism; functional genes |
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