Growth-promoting mechanism of the endophytic fungus KLBMP0506 on Arabidopsis thaliana

Abstract:

[Objective] To investigate the effect and mechanism of Wickerhamomyces sp. KLBMP0506 in promoting the growth of Arabidopsis thaliana. [Methods] The strain KLBMP0506 was co-cultured with the wild-type A. thaliana in plates and inoculated in the A. thaliana plants cultivated in pots. The growth and physiological indexes of A. thaliana were determined, including fresh weight, dry weight, taproot length, number of lateral roots, chlorophyll content, and soluble sugar content. Further, qRT-PCR was performed on 11 selected genes involved in lateral root and taproot formation and auxin synthesis and transportation in A. thaliana. [Results] The inoculation with the target strain KLBMP0506 increased the fresh weight and lateral root number of A. thaliana in plates and the fresh weight, dry weight, stem length, chlorophyll content, and soluble sugar content of A. thaliana cultivated in pots. The partition plate test and analysis of the promotive substances in the fermentation broth of the strain KLBMP0506 showed that the volatile organic substances produced by the strain and the n-butanol and ethyl acetate extracts of the fermentation broth had significant growth-promoting effects on A. thaliana. In addition, after treatment with KLBMP0506, the expression levels of ABI4 and FLA1 involved in the lateral root formation were down-regulated, and those of AUX1, EIR1, and YUC4 involved in auxin synthesis and transportation were up-regulated. The results indicated that the strain KLBMP0506 may promote the growth of A. thaliana by regulating the expression of genes associated with lateral root formation and auxin synthesis and transport. [Conclusion] This study confirmed the growth-promoting effect of strain KLBMP0506 on the model plant A. thaliana, providing a theoretical basis for developing microbial fertilizers with the strain.