CSIR-National Botanical Research Institute, Lucknow, Uttar Pradesh, India.
Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, Uttar Pradesh, India.
Microbiol Spectr. 2022 Oct 26;10(5):e0118622. doi: 10.1128/spectrum.01186-22. Epub 2022 Sep 6.
Propiconazole (PCZ) is a commonly sprayed fungicide against fungal pathogens. Being systemic in action, it reaches subcellular layers and impacts the endophytes. Although PCZ is a fungicide, it is hypothesized to exert an inhibitory effect on the bacterial endophytes. Therefore, this study aims to get an insight into the perturbations caused by the systemically acting antifungal agents PCZ and Bacillus subtilis (W9) and the consequences thereof. The current study compared the 16S rRNA microbial diversity, abundance, and functions of the endophytic bacterial community of tomato in response to PCZ, W9, and PCZ+W9 application. The implications of these treatments on the development of bacterial speck disease by Pseudomonas syringae were also studied. The culturable endophyte population fluctuated after (bio)fungicide application and stabilized by 72 h. At 72 h, the endophyte population was ~3.6 × 10 CFUg in control and ~3.6 × 10 in W9, ~3.0 × 10 in PCZ, and ~5.3 × 10 in PCZ+W9 treatment. A bacterial community analysis showed a higher relative abundance of , , , , and in the W9 treatment compared with that in the PCZ treatment and control. Phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) analysis showed enhanced metabolic pathways related to secretion, stress, chemotaxis, and mineral nutrition in the W9 treatment. Disease severity was greater in PCZ than that in the W9 treatment. Disease severity on tomato plants showed strong negative correlations with (r = -0.860) and (r = -0.810), indicating that the natural biocontrol communities are agents of plant resistance to diseases. Outcomes show that systemic chemicals are a potential threat to the nontarget endophytes and that plants became susceptible to disease on endophyte decline; this issue could be overcome by the application of microbial inoculums. Endophytes are plant inhabitants acting as its extended genome. The present study highlights the importance of maintaining plant endophytes for sustainable disease resistance in plants. The impact of chemical fungicides and biofungicides was shown on tomato endophytes, in addition to their implications on plant susceptibility to bacterial speck disease. The observations point toward the deleterious effects of systemic pesticide application on endophyte niches that disrupt their diversity and functions compromising plant immunity.
丙环唑（PCZ）是一种常用于防治真菌病原体的喷雾杀菌剂。作为一种具有全身作用的杀菌剂，它可以到达亚细胞层并影响内生菌。虽然 PCZ 是一种杀菌剂，但据推测它会对细菌内生菌产生抑制作用。因此，本研究旨在深入了解具有全身作用的抗真菌剂 PCZ 和枯草芽孢杆菌（W9）引起的干扰及其后果。本研究比较了番茄内生细菌群落对 PCZ、W9 和 PCZ+W9 应用的 16S rRNA 微生物多样性、丰度和功能。还研究了这些处理对丁香假单胞菌引起的细菌性斑点病发展的影响。在（生物）杀菌剂应用后，可培养内生菌种群波动，72 小时后稳定。72 小时时，对照和 W9 处理中的内生菌种群约为 3.6×10 CFUg，PCZ 处理中约为 3.0×10 CFUg，PCZ+W9 处理中约为 5.3×10 CFUg。细菌群落分析显示，W9 处理中相对丰度较高的是、、、和。与 PCZ 处理和对照相比，PICRUSt 分析显示，W9 处理中与分泌、应激、趋化和矿物质营养相关的代谢途径增强。番茄植株上的病害严重程度在 PCZ 处理中大于 W9 处理。番茄植株上的病害严重程度与（r = -0.860）和（r = -0.810）呈强负相关，表明天然生物防治群落是植物对疾病抗性的因子。研究结果表明，系统化学物质对非目标内生菌是一种潜在威胁，而内生菌的减少会使植物易受疾病影响；通过应用微生物接种物可以克服这个问题。内生菌是作为植物扩展基因组的植物居民。本研究强调了维持植物内生菌对植物可持续疾病抗性的重要性。本研究还展示了化学杀菌剂和生物杀菌剂对番茄内生菌的影响，以及它们对植物对细菌性斑点病易感性的影响。这些观察结果表明，系统农药的应用对破坏内生菌多样性和功能的内生菌小生境具有有害影响，从而损害植物的免疫力。
