Department of Plant Pathology, Vicosa Federal University, Vicosa, Brazil.
Phytopathology. 2012 Oct;102(10):957-66. doi: 10.1094/PHYTO-02-12-0037-R.
Silicon amendments to soil have resulted in a decrease of diseases caused by several soilborne pathogens affecting a wide number of crops. This study evaluated the physiological and biochemical mechanisms that may have increased resistance of banana to Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense, after treatment with silicon (Si) amendment. Plants from the Grand Nain (resistant to F. oxysporum f. sp. cubense) and "Maçã" (susceptible to F. oxysporum f. sp. cubense) were grown in plastic pots amended with Si at 0 or 0.39 g/kg of soil (-Si or +Si, respectively) and inoculated with race 1 of F. oxysporum f. sp. cubense. Relative lesion length (RLL) and asymptomatic fungal colonization in tissue (AFCT) were evaluated at 40 days after inoculation. Root samples were collected at different times after inoculation with F. oxysporum f. sp. cubense to determine the level of lipid peroxidation, expressed as equivalents of malondialdehyde (MDA), hydrogen peroxide (H(2)O(2)), pigments (chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids), total soluble phenolics (TSP), and lignin-thioglycolic acid (LTGA) derivatives; the activities of the enzymes phenylalanine ammonia-lyases glucanases (PALs), peroxidases (POXs), polyphenoloxidases (PPOs), β-1,3-glucanases (GLUs), and chitinases (CHIs); and Si concentration in roots. Root Si concentration was significantly increased by 35.3% for the +Si treatment compared with the -Si treatment. For Grand Nain, the root Si concentration was significantly increased by 12.8% compared with "Maçã." Plants from Grand Nain and "Maçã" in the +Si treatment showed significant reductions of 40.0 and 57.2%, respectively, for RLL compared with the -Si treatment. For the AFCT, there was a significant reduction of 18.5% in the +Si treatment compared with the -Si treatment. The concentration of MDA significantly decreased for plants from Grand Nain and "Maçã" supplied with Si compared with the -Si treatment while the concentrations of H(2)O(2) on roots and pigments on leaves significantly increased. The concentrations of TSP and LTGA derivatives as well as the PALs, PPOs, POXs, GLUs, and CHIs activities significantly increased on roots of plants from Grand Nain and "Maçã" from the +Si treatment compared with the -Si treatment. Results of this study suggest that the symptoms of Fusarium wilt on roots of banana plants supplied with Si decreased due to an increase in the concentrations of H(2)O(2), TSP, and LTGA derivatives and greater activities of PALs, PPOs, POXs, GLUs, and CHIs.
土壤中的硅改良导致了几种土传病原体引起的疾病减少，这些病原体影响了许多作物。本研究评估了香蕉对尖孢镰刀菌枯萎病（由尖孢镰刀菌古巴专化型引起）的抗性增强的生理生化机制，硅（Si）处理后。用 Si 处理（0 或 0.39 g/kg 土壤，分别为-Si 或+Si）和接种尖孢镰刀菌古巴专化型 1 号菌株，在塑料盆中种植大蕉（对尖孢镰刀菌古巴专化型有抗性）和“Maçã”（对尖孢镰刀菌古巴专化型敏感）。接种后 40 天评估相对病变长度（RLL）和组织中无症状真菌定殖（AFCT）。接种尖孢镰刀菌古巴专化型后不同时间采集根样，测定丙二醛（MDA）、过氧化氢（H₂O₂）、色素（叶绿素 a、叶绿素 b、总叶绿素和类胡萝卜素）、总可溶性酚（TSP）和木质素-巯基乙酸（LTGA）衍生物的脂质过氧化水平；苯丙氨酸解氨酶、葡聚糖酶（PALs）、过氧化物酶（POXs）、多酚氧化酶（PPOs）、β-1,3-葡聚糖酶（GLUs）和几丁质酶（CHIs）的活性；根中的 Si 浓度。与-Si 处理相比，+Si 处理使根中 Si 浓度显著增加 35.3%。对于大蕉，根中 Si 浓度比“Maçã”高 12.8%。与-Si 处理相比，+Si 处理使大蕉和“Maçã”的根 RLL 分别显著降低 40.0%和 57.2%。对于 AFCT，与-Si 处理相比，+Si 处理显著降低了 18.5%。与-Si 处理相比，Si 处理使大蕉和“Maçã”的根中 MDA 浓度显著降低，而根中的 H₂O₂浓度和叶片中的色素浓度显著增加。与-Si 处理相比，Si 处理使大蕉和“Maçã”的根中 TSP 和 LTGA 衍生物以及 PALs、PPOs、POXs、GLUs 和 CHIs 的浓度显著增加。与-Si 处理相比，Si 处理使大蕉和“Maçã”的根中 H₂O₂、TSP 和 LTGA 衍生物以及 PALs、PPOs、POXs、GLUs 和 CHIs 的活性显著增加。本研究结果表明，由于 H₂O₂、TSP 和 LTGA 衍生物浓度以及 PALs、PPOs、POXs、GLUs 和 CHIs 活性的增加，Si 处理的香蕉植株根部的镰刀菌枯萎病症状减轻。
