Institute of Sustainable Plant Protection (IPSP), National Research Council of Italy (CNR), 70126, Bari, Italy.
Institute of Sciences of Food Production (ISPA), National Research Council of Italy (CNR), 70126, Bari, Italy.
Plant Cell Rep. 2017 Apr;36(4):621-631. doi: 10.1007/s00299-017-2109-0. Epub 2017 Feb 26.
Salicylic acid-signaling pathway and ethylene biosynthesis were induced in tomato treated with Trichoderma harzianum when infected by root-knot nematodes and limited the infection by activation of SAR and ethylene production. Soil pre-treatment with Trichoderma harzianum (Th) strains ITEM 908 (T908) and T908-5 decreased susceptibility of tomato to Meloidogyne incognita, as assessed by restriction in nematode reproduction and development. The effect of T. harzianum treatments on plant defense was detected by monitoring the expression of the genes PR-1/PR-5 and JERF3/ACO, markers of the SA- and JA/ET-dependent signaling pathways, respectively. The compatible nematode-plant interaction in absence of fungi caused a marked suppression of PR-1, PR-5, and ACO gene expressions, either locally or systemically, whilst expression of JERF3 gene resulted unaffected. Conversely, when plants were pre-treated with Th-strains, over-expression of PR-1, PR-5, and ACO genes was observed in roots 5 days after nematode inoculation. JERF3 gene expression did not change in Th-colonized plants challenged with nematodes. In the absence of nematodes, Trichoderma-root interaction was characterized by the inhibition of both SA-dependent signaling pathway and ET biosynthesis, and, in the case of PR-1 and ACO genes, this inhibition was systemic. JERF3 gene expression was systemically restricted only at the very early stages of plant-fungi interaction. Data presented indicate that Th-colonization primed roots for Systemic Acquired Resistance (SAR) against root-knot nematodes and reacted to nematode infection more efficiently than untreated plants. Such a response probably involves also activation of ET production, through an augmented transcription of the ACO gene, which encodes for the enzyme catalyzing the last step of ET biosynthesis. JA signaling and Induced Systemic Resistance (ISR) do not seem to be involved in the biocontrol action of the tested Th-strains against RKNs.
水杨酸信号通路和乙烯生物合成在番茄感染根结线虫时被诱导，这限制了感病性通过 SAR 和乙烯产生的激活。在番茄上进行的生防菌哈茨木霉（Trichoderma harzianum）的土壤预处理（用菌株 ITEM 908（T908）和 T908-5 进行处理），通过限制线虫繁殖和发育，降低了番茄对南方根结线虫（Meloidogyne incognita）的易感性。通过监测水杨酸（SA）和茉莉酸（JA）/乙烯（ET）依赖性信号通路的标记基因 PR-1/PR-5 和 JERF3/ACO 的表达，来检测生防菌处理对植物防御的影响。在没有真菌的情况下，亲和型的线虫-植物互作导致 PR-1、PR-5 和 ACO 基因的表达受到明显抑制，无论是局部还是系统表达，而 JERF3 基因的表达则不受影响。相反，当植物用 Th 菌株预处理时，在接种线虫后 5 天，根部观察到 PR-1、PR-5 和 ACO 基因的过表达。在受到线虫挑战的 Th 定殖植物中，JERF3 基因的表达没有变化。在没有线虫的情况下，木霉-根的相互作用特征是抑制 SA 依赖性信号通路和 ET 生物合成，并且在 PR-1 和 ACO 基因的情况下，这种抑制是系统性的。只有在植物-真菌相互作用的早期阶段，JERF3 基因的表达才受到系统性限制。所呈现的数据表明，Th 定殖使根对根结线虫的系统性获得抗性（SAR）做好准备，并比未经处理的植物更有效地应对线虫感染。这种反应可能还涉及 ET 产生的激活，这是通过 ACO 基因的转录增强来实现的，ACO 基因编码 ET 生物合成的最后一步的酶。JA 信号和诱导系统抗性（ISR）似乎不参与所测试的 Th 菌株对 RKNs 的生防作用。
