The correlation between elicitors and plant hormones, and the application of elicitors in improving the post-shipping quality of Phalaenopsis orchids.
| Autor: | Cai-Hua Sun, 孫彩華 |
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| Rok vydání: | 2010 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 98 Chapter1. Abstract Pathogen-or microbe-associated molecular patterns (PAMPs or MAMPs) are used as inducers (elicitors) to trigger defense response in plants. Harpin and Chitosan can be as elicitors. Harpin is an acidic protein isolated originally from plant pathogenic bacterium Erwinia amylovora. Harpin has been shown to simulate plant growth and resistance to pathogens and insects. Chitosan, a deacetylated form of chitin, a component present in the outer shell of crustaceans or the cell wall of fungi, has been used to control microbial growth and to induce defense response in plant cells. Plant hormones not only play important roles in the regulation of plant growth, but also interact with signaling pathways controlling defense response. In this study, harpin and chitosan were applied to Arabidopsis to induce similar PR gene expression and repress auxin-inducible gene expression, respectively. By detecting the PR gene expression in mutants defective in hormone perception, including auxin, ET, and ABA, revealed that the harpin-induced PR gene expression was reduced in the ABA and ET insensitive mutants. These results suggested that ABA and ET were positive factors in the harpin-induced PR gene expression. Nevertheless, the chitosan-induced gene expression was suppressed in the ET insensitive mutant, but was enhanced in the ABA insensitive mutant, suggesting that ET was a positive, but ABA was a negative factor for the chitosan-induced gene expression, respectively. In summary, our results demonstrate that ET signal is required for both harpin- and chitosan-induced PR gene expression, while, ABA plays differential roles in these gene expression. Chapter2. Abstract Phalaenopis sp. is an important floral crop in Taiwan. Shipping potted Phalaenopsis in sphagnum moss usually resulted in physiological-yellow leaf and disease infection caused by the microbes contaminated in the growing medium. Harpin and chitosan can be used elicitors to induce defense responses in plant cells. Harpin is an acidic protein secreted from plant pathogen of Erwinia amylovora. Chitosan is a deacetylated form of chitin. In this study, we investigated the effectiveness of harpin and chitosan in improving the quality of Phalaenopsis plants after a simulated shipping. The results showed that after 3-4 weeks of shipping simulation process, number of disease infective plants was reduced in the harpin treatment, but was increased in the chitosan treatment, respectively. Western blot analysis indicated that protein levels of superoxide dismutase (SOD) were accumulated to high levels by both treatments of harpin and chitosan at the pre-storage stage, while at the post-storage stage, the SOD protein was induced in all treatments. These results indicated that 3 to 4 weeks of shipping simulation process resulted in high level of stress in Phalaenopsis plants, hence a large amount of SOD protein was accumulated in the control treatment. The pathogenesis-related protein 2 (PR2) was also induced by both harpin and chitosan treatments at the pre-storage stage, however, at the post-storage stage, the PR2 protein was enhanced in the harpin treatment, but suppressed in the chitosan treatment. The PR2 protein levels were well correlated with the disease infection rate of Phalaenospis at the post-storage stage. The efficacy of harpin and chitosan in inducing defense response against pathogen infection was tested in Phalaenopsis plants infected by fungal pathogen, Fusarium solani. Our results showed that both harpin and chitosan could reduce disease infection symptoms in treated plants. In summary, the results of this study show that both harpin and chitosan can induce defense response in Phalaenopsis orchid. Harpin is a potent inducer for inducing a long-lasting disease resistance which can reduce disease infection rate efficiently in the potty Phalaenopsis under sea freight shipping process. However, the defense response induced by chitosan is comprised by physiological stress generated from the shipping process. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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