The autotoxicity of root exudates is an important factor that affects soil enzymes and microbes in rhizosphere soil. Previous studies have confirmed that 2,4-di-tert-butylphenol (2,4-DTBP) is a major autotoxin of the root exudates that severely hampers the yield and quality of Lanzhou lily. However, little is currently known regarding the mechanism of 2,4-DTBP. Here, we hypothesized that 2,4-DTBP has a direct effect on soil functionality and the microbial community structure in Lanzhou lily rhizosphere soil, thereby affecting the growth of Lanzhou lily. To test our hypothesis, various experiments were conducted in this study. We treated Lanzhou lily plants with 2,4-DTBP at different concentrations and analyzed the effects of 2,4-DTBP on rhizosphere soil enzyme activity and microbial community structure and function. The diversity of soil microbes was analyzed using high-throughput sequencing. The results showed that 2,4-DTBP altered rhizosphere soil enzyme activity and microbial community structure and function. Moreover, microbial biomass was stimulated with the addition of 0.5 mM 2,4-DTBP and inhibited with the addition of 2.0 mM 2,4-DTBP. Thus, the 2.0 mM 2,4-DTBP treatment was not suitable for the growth of soil microorganisms. We also found that the 2.0 mM 2,4-DTBP treatment resulted in an increase in the levels of fungal pathogens, such as Fusarium, and reduced the size of beneficial bacterial populations in the rhizosphere soil. Moreover, the effects of 2,4-DTBP on soil functionality and the microbial community structure differed based on the concentrations of 2,4-DTBP and the specific indexes of determination. Thus, we concluded that 2,4-DTBP could inhibit soil functionality and disturb the microbial community structure in the rhizosphere soil. This finding may be important for understanding the relationship between autotoxicity and barriers and clarifying the long-term continuous cropping problems of Lanzhou lily.

根系分泌物的自毒作用是影响根际土壤酶和微生物的重要因素。以前的研究已经证实，2,4-二-叔-丁基苯酚（2,4-DTBP）是根系分泌物的主要自体毒素，严重影响兰州百合的产量和品质。然而，目前对 2,4-DTBP 的机制知之甚少。在这里，我们假设 2,4-DTBP 对兰州百合根际土壤的土壤功能和微生物群落结构有直接影响，从而影响兰州百合的生长。为了验证我们的假设，本研究进行了各种实验。我们用不同浓度的 2,4-DTBP 处理兰州百合植物，并分析了 2,4-DTBP 对根际土壤酶活性和微生物群落结构和功能的影响。使用高通量测序分析土壤微生物的多样性。结果表明，2、4-DTBP 改变了根际土壤酶活性和微生物群落结构和功能。此外，添加 0.5 mM 2,4-DTBP 刺激微生物生物量，添加 2.0 mM 2,4-DTBP 抑制微生物生物量。因此，2.0 mM 2,4-DTBP 处理不适合土壤微生物的生长。我们还发现 2.0 mM 2,4-DTBP 处理导致真菌病原体水平增加，例如镰刀菌，并减少了根际土壤中有益细菌种群的大小。此外，2,4-DTBP 对土壤功能和微生物群落结构的影响因 2,4-DTBP 的浓度和具体测定指标而异。因此，我们得出结论，2,4-DTBP 可以抑制土壤功能并扰乱根际土壤中的微生物群落结构。这一发现可能对理解自毒与屏障之间的关系以及阐明兰州百合长期连作问题具有重要意义。