---

作 者 ：董 梅,王建武,徐 涛.

期 刊 ：中国生态农业学报 2008年 16卷 4期 页码：887-893

关键词：外源乙烯利；玉米；化学防御；丁布；防御基因表达；

Keywords:Exogenous ethephon, Maize, Chemical defense, DIMBOA, Defense gene expression,

摘 要 ：为探明外源乙烯利对玉米化学防御作用诱导的浓度和时间效应，本文采用化学和分子生物学相结合的方法，研究了不同浓度乙烯利处理玉米后，叶片乙烯释放量及其合成调控关键基因ACS和ACO表达的变化，典型化感物质丁布的含量及其关键调控基因BX₁和BX₉表达的变化，以及其他调控次生代谢物的关键基因表达的时间动态。结果表明，外源乙烯利处理玉米12 h时，玉米叶片中丁布含量明显增加；24 h后，丁布含量反而大量降低，48 h后对丁布含量影响不大。外源乙烯利对合成丁布的调控基因BX₁没有诱导作用，但处理12 h和24 h对BX₉有明显诱导作用。外源乙烯利处理12 h能够使ACS和ACO表达量上升，浓度为40 μL·L^-1和60 μL·L^-1乙烯利处理使玉米叶片丁布含量大量降低，BX₁和BX₉的表达量有所下调。外源乙烯利能够使蛋白酶抑制剂MPI表达量升高，且乙烯利浓度越高，诱导作用越明显，但对调控挥发物的FPS和TPS基因表达没有影响。说明外源乙烯利能够启动玉米体内的乙烯途径，诱导玉米启动化学防御过程，但这种作用很可能是负反馈型的。

Abstract:In this study, the amount of ethylene and its key biosynthesis genes (ACS and ACO) expression, typical allelochemical hydroxamic acid (DIMBOA) concentration and the key regulation genes (BX₁ and BX₉), as well as the dynamic expression and time of relevant defense key genes of secondary substance metabolism processes were compared in ethephon treatments of different concentration and duration. The main objective was to build further understanding into the role of ethylene signal pathway in the process of induced defense in maize. The results show that ethylene signal pathway occurs during induced chemical defense mechanism in maize. The amount of ethylene released from the second leaf and the concentration of DIMBOA significantly increase in maize after treatment for 12 h, but both variables decrease significantly after 24 h.ACS, ACO andBX₉ gene expression up regulates at 12 h and 24 h, but BX₁ gene completely fails to be expressed. Meanwhile, DIMBOA decreases when concentration of exogenous ethylene is high (40～60 μL·L^-1). Exogenous ethylene treatment leads to high expression of proteinase inhibitor MPI defense gene, and the expression gets stronger with increasing concentration of exogenous ethylene. However, exogenous ethylene dose not influence FPS and TPS expression. In conclusion therefore, exogenous ethephon treatment induces chemical defense in maize, but ethylene content in maize is a negative feedback regulation mechanism that variously leads to metabolic reconfiguration and activation of direct and indirect responses of defense genes.

---