Institute for Sustainable Plant Protection, IPSP-Bari Unit, Department of Biology, Agricultural and Food Sciences, DISBA, National Council of Research, CNR, 70126 Bari, Italy.
Int J Mol Sci. 2023 Oct 21;24(20):15416. doi: 10.3390/ijms242015416.
Commercial formulations of beneficial microbes have been used to enrich the rhizosphere microbiome of tomato plants grown in pots located in a glasshouse. These plants have been subjected to attacks by soil-borne parasites, such as root-knot nematodes (RKNs), and herbivores, such as the miner insect The development of both parasites and the symptoms of their parasitism were restricted in these plants with respect to plants left untreated. A mixture, named in the text as Myco, containing plant growth-promoting rhizobacteria (PGPR), opportunistic biocontrol fungi (BCF), and arbuscular mycorrhizal fungi (AMF) was more effective in limiting pest damage than a formulation containing the sole AMF (Ozor). Therefore, Myco-treated plants inoculated with RKNs were taken as a model for further studies. The PGPR contained in Myco were not able to reduce nematode infection; rather, they worsened symptoms in plants compared with those observed in untreated plants. Therefore, it was argued that both BCF and AMF were the microorganisms that colonized roots and stimulated the plant immune system against RKNs. Beneficial fungi colonized the roots by lowering the activities of the defense supporting enzymes endochitinases and β-1,3-glucanase. However, as early as three days after nematode inoculation, these enzyme activities and the expression of the encoding pathogenesis-related genes (, ) were found to be enhanced in roots with respect to non-inoculated plants, thus indicating that plants had been primed against RKNs. The addition of paclobutrazol, which reduces salicylic acid (SA) levels in cells, and diphenyliodonium chloride, which inhibits superoxide generation, completely abolished the repressive effect of Myco on nematode infection. Inhibitors of copper enzymes and the alternative cyanide-resistant respiration did not significantly alter resistance induction by Myco. When Myco-treated plants were subjected to moderate water stress and inoculated with nematodes, they retained numbers of developed individuals in the roots similar to those present in regularly watered plants, in contrast to what occurred in roots of untreated stressed plants that hosted very few individuals because of poor nutrient availability.
商业制剂的有益微生物已被用于丰富温室盆栽番茄植物根际微生物组。这些植物受到土壤寄生虫（如根结线虫（RKNs））和草食动物（如矿工昆虫）的攻击。与未经处理的植物相比，这些植物中寄生虫的发育和寄生症状都受到了限制。一种名为“Myco”的混合物，含有植物生长促进根际细菌（PGPR）、机会生物防治真菌（BCF）和丛枝菌根真菌（AMF），比仅含 AMF（Ozor）的制剂更能有效限制害虫的损害。因此，接种 RKN 的 Myco 处理过的植物被作为进一步研究的模型。Myco 中含有的 PGPR 不能减少线虫感染；相反，它们使植物的症状比未处理的植物更严重。因此，有人认为 BCF 和 AMF 都是定植在根上并刺激植物免疫系统对抗 RKN 的微生物。有益真菌通过降低防御支持酶几丁质酶和β-1,3-葡聚糖酶的活性来定植在根上。然而，早在接种线虫三天后，与未接种植物相比，这些酶的活性和编码与发病机制相关的基因（、）的表达在根中就得到了增强，从而表明植物已经对 RKN 进行了启动。添加能降低细胞中水杨酸（SA）水平的多效唑和抑制超氧化物生成的二苯基碘𬭩氯化物，完全消除了 Myco 对线虫感染的抑制作用。铜酶抑制剂和替代的氰化物抗性呼吸对 Myco 诱导的抗性没有显著影响。当用 Myco 处理过的植物受到适度水分胁迫并接种线虫时，它们在根中保留的发育个体数量与定期浇水的植物相似，而未经处理的受胁迫植物的根中由于营养可用性差，仅存在极少数个体。
