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Acta Prataculturae Sinica ›› 2025, Vol. 34 ›› Issue (4): 175-188.DOI: 10.11686/cyxb2024194

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Effects of three endophytic bacteria in the roots of Salvia miltiorrhiza on host growth and medicinal quality

Zhao MA1(), Xiao-fan LI2, Li-qiong SUN1, Zhi HUANG3, Lei XU2, Ting LU2, Xiao-qing TANG1(), Kang-cai WANG1   

  1. 1.College of Horticulture,Nanjing Agricultural University,Nanjing 210095,China
    2.Suzhou Qifan Agricultural Technology Limited Company,Changshu 215500,China
    3.College of Life Science,Nanjing Agricultural University,Nanjing 210095,China
  • Received:2024-05-21 Revised:2024-06-20 Online:2025-04-20 Published:2025-02-19
  • Contact: Xiao-qing TANG

Abstract:

A pot experiment was conducted to study the effects of three endophytic bacteria on the growth, physiology, and medicinal quality of Salvia miltiorrhiza. The ultimate aim of this research was to identify bacteria suitable for the development of microbial fertilizers for S. miltiorrhiza. Three endophytic bacteria (Mesorhizobium amorphae B546, Bacillus thuringiensis NB49, and B. thuringiensis Bt12) isolated from the roots of S. miltiorrhiza were applied to seedlings via root irrigation. The growth and physiological indicators were measured at different times (7, 14, 28, 42, 56 d) after treatment, and the contents of eight active ingredients in the roots were determined at harvest. It was found that all three endophytic bacteria significantly promoted the accumulation of S. miltiorrhiza biomass. After 56 days of growth, the diameter of the main root and the dry weight of the above ground and underground parts were significantly higher (by 1.21-2.49 times) in all the treatments than in the uninoculated control (CK) (P<0.05). The endophytic bacterial treatments had a significant impact on the physiology of S. miltiorrhiza, with B. thuringiensis Bt12 having the best promoting effect. After 42 days of growth, the contents of soluble sugars, soluble proteins, total chlorophyll, zein, 6-benzylaminopurine, and auxin were 1.36- to 2.18-times higher in the treatments than in CK. The three endophytic bacteria strains exerted distinct effects on the accumulation of active components in S.miltiorrhiza. Notably, B. thuringiensis Bt12 significantly enhanced the accumulation of total tanshinone and total salvianolic acid to levels 2.10- and 1.37-times that in CK, respectively. M. amorphae B546 and B. thuringiensis NB49 promoted the accumulation of total tanshinone, to levels 1.08- and 1.34-times that in CK, respectively, but inhibited the accumulation of phenolic acids, with the total phenolic acid content being 92.21% and 69.29% of that in CK, respectively. In summary, the three strains of endophytic bacteria significantly affected the growth, physiological metabolism, and accumulation of active ingredients in S. miltiorrhiza. Among the tested endophytic bacteria, B. thuringiensis Bt12 had the strongest promoting effect. Thus, it has potential applications in the development of specialized microbial fertilizers for S. miltiorrhiza.

Key words: Salvia miltiorrhiza, endophytic bacteria, microbial fertilizers, promote growth, medicinal quality