内生真菌KLBMP0506对拟南芥的促生作用

【目的】研究植物内生菌Wickerhamomyces sp.KLBMP0506对拟南芥（Arabidopsis thaliana）的促生作用及潜在的促生机制。【方法】本研究以野生型拟南芥为试验材料，将其与菌株KLBMP0506进行平板共培养及盆栽接种试验，并测定拟南芥鲜重、干重、主根长、侧根数、叶绿素含量和可溶性糖含量等生长、生理指标，同时对筛选的与拟南芥侧根、主根形成及生长素合成和运输相关的11个基因进行实时荧光定量聚合酶链式反应（quantitative real-time polymerase chain reaction，qRT-PCR）分析。【结果】接种目的菌株KLBMP0506后，平板试验的拟南芥鲜重及侧根、盆栽试验的拟南芥鲜重、干重、茎长、叶绿素含量和可溶性糖含量均有一定程度的增加；分隔平板试验及菌株KLBMP0506发酵液中促生活性物质分析显示，该菌株产生的挥发性有机物质及其发酵液中的正丁醇和乙酸乙酯提取物均对拟南芥有明显的促生作用；此外，qRT-PCR分析显示KLBMP0506处理后，拟南芥中与侧根形成相关基因ABI4、FLA1的表达出现不同程度的下调，与生长素合成、运输相关基因AUX1、EIR1、YUC4的表达整体呈上调趋势，表明菌株KLBMP0506可能通过调控拟南芥中与侧根形成以及与生长素合成和运输相关基因的表达，而实现对拟南芥的促生作用。【结论】本研究明确了菌株KLBMP0506对模式植物拟南芥的促生作用，为其开发成为微生物菌肥提供理论依据。

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

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.