水稻過氧化氫調節之微核醣核酸

Abstract

在植物，過氧化氫是新陳代謝過程中自然產生的高活性氧化劑，其在植物逆境反應中扮演訊號調節分子。微核醣核酸藉由降解訊息核醣核酸或是抑制其轉譯作用，而參與眾多重要生物反應。至今，僅有少數研究進行探討與闡述氧化壓力下其微核醣核酸的功能。因此我們整合小核酸及降解組定序平台之策略來揭示水稻中可受過氧化氫調節之微核醣核酸功能。在此研究中，我們更新了水稻中可受過氧化氫調節之微核醣核酸資訊，並且藉由整合比較微核醣核酸生成路徑突變體及Argonaute蛋白免疫沉澱定序資料，我們發現五種新型可受過氧化氫調節之微核醣核酸。透過實驗驗證，其中一個新型微核醣核酸的功能也被確認為於過氧化氫逆境下會進行調節類囊體腔蛋白及丙酮酸脫羧酶的基因表現。透過我們新建立的降解組比較分析方法與篩選標準，我們找到了許多未被報導的微核醣核酸標的基因。藉由以上相關實驗證據，我們也提出了一個在過氧化氫壓力下水稻透過微核醣核酸調節點進行影響根構型可塑性之機制。

Hydrogen peroxide (H2O2) is a strong oxidizer and natural by-product of cellular metabolism that acts as a regulatory molecule in stress perception and signal transduction in plants. microRNAs (miRNAs) play a significant role in regulating gene expressions via degradation or translational inhibition of their target mRNAs in many biological processes. Until now, only few studies have focused on dissecting the complexity of small RNAs (sRNAs) under oxidative stress. To reveal the landscape of H2O2 regulated miRNAs in rice, various analyzing strategies including sRNA sequencing and degradome sequencing were performed in this study. Through these approaches, we updated a new list of hydrogen peroxide regulated miRNAs in the rice root. Besides, by conducting miRNA prediction and comparing sequencing data from silencing mutants and AGO-immunoprecipitation data, we revealed five novel H2O2 regulated miRNAs and confirmed the function of one novel miRNA for targeting the transcript of thylakoid lumen protein and pyruvate decarboxylase isozyme1 under H2O2 stress. By applying a new visualization approach to compare miRNA mediated degradation patterns among different conditions together with our newly defined degradome filtering criteria we were able to reveal more novel miRNA-target relationships. Based on the comparison between the expression of miRNAs and degradome validated targets, we proposed a model for the role of miRNA in regulating root architecture plasticity under H2O2 treatment in rice.