Studies on the application of the endophytic bacteria to enhance tomato growth and tolerance to biotic stress
| Autor: | Zi-Jie Wang, 王梓傑 |
|---|---|
| Rok vydání: | 2017 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 105 Tomato (Solanum lycopersicum) is an important cash crop widely grown in temperate climates across the world. In Taiwan, approximately 5,000 ha, mainly in the middle and south parts of Taiwan, were used for tomato production, and the annual yield is about 120 thousand tons. During cultivation, tomato plants may encounter attack of different pathogens such as Ralstonia solanacearum and Fusarium oxysporum f.sp. lycopersici. Although common strategies, such as crop rotation, soil sterilization, use of resistant cultivars or grafted seedlings and application of pesticides, are available for tomato disease management, much safer and eco-friendly means are worth of development. To take advantage of the intimate interaction with plants, application of endophytes with ability to enhance tomato resistance and plant growth should shed light on improvement of tomato production. In this study, endophytic bacteria were isolated from tomato plants by luring or direct isolation, which were then used to perform assays for investigation of the plant growth-promoting activities, including phosphate solubilization, siderophore production and IAA biosynthesis. In order to understand their potentials to enhance tomato tolerance to various biotic stress, antagonistic effects against different tomato pathogens in vitro as well as pathogenicity assays was performed. One hundred and twenty-eight potential endophytic bacteria strains were isolated and tomato plants treated with 7 isolates, including XK1-13, XP1-3, XP1-8, XP2-2, XR2-3, MK2-1 and A7, showed increased biomass compared to control plants. Among these 7 isolates, the effect of XP1-8 and A7 on plant growth was more significant. They showed 30.89% and 46.57% increase in dry weight compared to control, respectively. On the other hand, the colonization sites and the colonization rates were assessed. The results showed that the endophytes mostly colonized in the hypocotyl of tomato.The highest colonization rate were detected when the tomato seedlings, whose root length is between 0.2 to 2 cm, wereco-cultured with these endophytes at the level of 1x108 CFU/mL for 48 hours. In an antagonistic activity assay, XK1-13, XP1-3 and A7 exhibited inhibitory activity on growth of Ralstonia solanacearum Pss97. In a pathogenicity assay, XP1-3, XP2-2, XR2-3 and MK2-1 caused delayed symptom development of bacterial wilt. In addition, XP2-2 and MK2-1 reduced the bacteria number of Xanthomonas perforans XTN169 in tomato leaves. At the end, A7 and XP1-8 was identified as Pseudomonas putida and Burkholderia tropica, respectively, by analysis of their 16S rDNA sequences. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
| Externí odkaz: |
|