訊息胜肽 AtPep 與 AtRALF 對阿拉伯芥在高鹽逆境反應與生長之影響

Abstract

近年來胜肽被廣泛的研究，其大部分的功能皆與參與植物訊息傳導和引發植物免疫系統防禦有關，而胜肽可作為植物生長或保護的調節劑並應用在農業上的特性也使胜肽的研究越來越受到重視。在本篇論文中，我們研究了做為訊息傳導胜肽的兩種胜肽，分別是植物激發胜肽 (Pep) 和快速鹼化因子 (RALF)，並希望從實驗結果中探討胜肽的潛在應用。在本研究中，我們首先建立異源表現重組胜肽 RALF14，RALF33 和 RALF34 的表現與純化系統，另外也利用化學合成的方法得到 Pep1、Pep3 和一些 RALF 部分保守序列的胜肽。本研究測試這些胜肽對阿拉伯芥面對鹽逆境，及對根長和發芽率的反應。在觀察根長的實驗中，發現在鹽逆境下用 Pep3 與 RALF34b 處理可使根長有加成性的抑制，但以 Pep1 與 RALF14 處理時，則沒有加成性的抑制現象。針對此結果，我們推測 RALF 和 Pep 在鹽逆境下是透過不同的路徑影響根長，且不同成員間的影響也不盡相同。此外，我們發現 RALF14 的較小片段 RALF14b 同樣可以引起根長的加成性抑制並使植物對鹽耐受性降低。最後，我們發現 Pep3 可以提高鹽逆境下老化種子的發芽率。這些發現揭示了這些訊息胜肽的功能比我們預期的更多，也提供了這些胜肽在農業應用中的不同面相的思考。

A diverse array of peptides involved in plant signaling and defense are gaining attention due to their possibility of being employed as a plant growth or protection regulator. In this study, known secreted peptides of plant elicitor peptides (Pep) and rapid alkalinization factors (RALF) families were explored for their potential applications in agriculture. Recombinant peptides of mature RALF14, RALF33 and RALF34 were constructed and purified in E. coli. Pep1, Pep3 and peptides containing the conserved motif of RALFs peptides were chemically synthesized. These peptides were applied on Arabidopsis thaliana to test their effects on salinity stress response, root lengths and seed germination. The results showed that under salinity stress, treatments with Pep3 and RALF34b, the smaller fragment of RALF34, could cause additive inhibition of roots length. However, the inhibition of root length caused by salinity was suppressed when treated with RALF14 and Pep1. RALF14b, the smaller fragment of RALF14, also caused additive inhibition of roots length and decreased salinity stress tolerance. These indicate that different members of RALF and Pep differentially affect root length under salinity stress. In addition, Pep3 could enhance the germination rate of aging seeds under salinity stress. These findings revealed that signaling peptides have more functions than we expected. Providing putative application of signaling peptides in agriculture.