Influence of Simulated Drought Stress on Seedling Growth and Bacterial Community in the Rhizosphere of Sainfoin
- XIA Jing, WEN Sujun, NAN Lili, WANG Kun, CHEN Jie
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【Objective】 The effects of drought stress on root growth and rhizosphere soil bacterial community of Onobrychis viciaefolia were investigated to provide a theoretical basis for improving drought tolerance and water use efficiency in sainfoin. 【Method】 The nutrient solution sand culture method was adopted, different sainfoin lines including three new lines of P1, P2, P3, Onobrychis viciaefolia ′Gansu′ and O. viciaefolia ′Mengnong′ were used. Drought stress was simulated with PEG-6000 with a water potential of -0.8 MPa of different stress time （0,3,6,and 9 days）. The total DNA of the seedling rhizosphere soil was extracted and amplicon sequencing of V4 region of 16S rRNA gene was performed to characterize the bacterial community structure of drought-treated sainfoin. 【Result】 With the prolonging of stress,the plant height and average root diameter of Onobrychis viciaefolia were increased, while the leaf area was decreased significantly （P<0.05）. Aboveground dry weight, root tip number, total root length, total root surface area,and root volume were significantly increased （P<0.05）, whereas underground dry weight, root shoot ratio, and root activity firstly increased and then decreased significantly （P<0.05）, and reached the maximum at 3 days of drought stress. The mean values of root tip number, root diameter, aboveground and underground dry weights of new sainfoin line of P1 were significantly higher than those of other lines （P<0.05） during the whole period of stress. The indices of Chao1, ACE, Simpson, and Shannon were first decreased and then increased （P<0.05）, and reached the maximum at 0 d. Chao1 and ACE indices were the lowest under drought stress of 6 days,whereas the diversity indices of Simpson and Shannon were the lowest under drought stress of 3 days. Proteobacteria,Firmicutes, Verrucomicrobia, Bacteroidetes, and Actinobacteria were dominant bacterial phyla. The drought stress time significantly increased the relative abundance of Proteobacteria ,decreased the relative abundance of Firmicutes, Actinobacteria, and Verrucomicrobia, and firstly decreased and then increased the relative abundance of Cyanobacteria and Bacteroidetes significantly （P<0.05）. 【Conclusion】 The new sainfoin line of P1 has better drought resistance. Modifying the microbial community structure and improving the soil microdomain environment can improve the drought stress tolerance of plants.