| Summary: | 碩士 === 國立高雄師範大學 === 生物科技系 === 107 === In order to understand the mechanism of 12-amino-acid synthetic peptide, IbACP, and 16-amino-acid synthetic peptide, Ba1-2(2), in plant physiology, tomato plants were treated with these two peptides and their RNAs were analyzed with NGS. Data shows that these two peptides involved in many reactions, including photosynthesis, metabolic process and plant defense. Genes regulated by IbACP were statistically analyzed, and 18.3% of them were enzyme activity-related, 16.1% of them were metabolic process-related and 15.3% of them were cellular component organization related. Also, 6.3% of IbACP-regulated genes were response to stimulus. By contrast, 17.8% genes affected by Ba1-2(2) were cellular component organization related, 17.6% were encoding binding proteins, 15.8% were enzyme activity related, and 7.3% were response to stimulus. To understand the role of IbACP and Ba1-2(2) peptides in plant defense pathway, two peptides were applied to tomato for 2 to 24 hours, respectively, and some defense-related genes were monited by semiquantitative PCR. The result showed that IbACP and Ba1-2(2) induce JA-synthesized related genes LoxD and AOS in 2 to 8 hours, and it suggested that two peptides induced the synthesis of JA in early stage. Morever, Ba1-2(2) inhibited SA-synthesized gene ICS within 12 hours, but induced it after. We hypothesized that the increasing JA content delayed the synthesis of SA due to the antagonism effect of JA and SA in the early period. On the other hand, our results showed that SA-dependent defense gene, NPR1, was up-regulated in the late period to promote plant defense mechanism. Ba1-2(2) peptide also induced the expression of ACO1, the ethylene-synthesis related genes, to enhance the production of ethylene. Furthermore, both IbACP and Ba1-2(2) peptides induce the gene expression of suberization-associated anionic peroxidases, TMP1 and TAP2. Suberization of plant cell wall may use to prevent pathogen invading. These results of this research indicated that IbACP and Ba1-2(2) peptides play important roles in plant defense mechanism. They induced the synthesis of defense-related hormones, and up-regulated defense genes in the downstream of signal transduction pathway to enhance the ability of resistance to biotic stress.
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