中文摘要：

在“高油115”玉米幼苗地下部施用4种不同浓度（10、50、100、200μmol·L^-1）的茉莉酸3～48h后，采用生化成分分析和基因表达分析方法，检测了处理部位（根系）和非处理部位（叶片）中防御物质及防御相关基因的表达，以探讨茉莉酸诱导玉米地下部对化学防御反应影响的时间和浓度效应．结果表明：茉莉酸处理玉米地下部对处理部位（根系）和非处理部位（叶片）化学防御反应的影响均与茉莉酸作用的时间和浓度相关．茉莉酸处理玉米地下部后，在3～12h内就能直接诱导处理部位（根系）Bx9、PAL、PR-2a、MPI和FPS基因的表达，使得根中的丁布含量增加而总酚含量下降，其中100μmol·L^-1茉莉酸处理浓度产生的诱导作用最强，其次是50μmol·L^-1，再次是10μmol·L^-1；后期诱导作用则逐渐减弱．另外，茉莉酸处理玉米地下部还能间接影响到非处理部位（叶片）的化学防御反应，50μmol·L^-1茉莉酸在处理后3h就能系统诱导叶片中Bx9和FPS基因的表达，使叶片的丁布含量增加；在6—24h内则使叶片Bx9、PAL、PR-1、MPI，和TPS基因表达量增加，丁布和总酚含量降低．可见，对于大部分检测指标来说，茉莉酸处理玉米地下部对地上部的间接诱导作用不如对地下部的直接诱导作用强，根系启动防御反应的时间较叶片早，同时，随着处理浓度的增加，茉莉酸对根系和叶片防御反应的诱导作用有增强趋势．

英文摘要：

Biochemical and gene expression analysis methods were adopted to investigate the defensive substances and the defense-related genes expression in the roots and leaves of maize （ Zea mays L. ） cultivar Gaoyou 115 after underground treatment with 10, 50, 100 and 200 μmol·L^-1 of jasmonic acid （JA） for 3-48 h, aimed to explore the timing- and concentration effect of belowground treatment with JA on the chemical defense response of maize. The chemical defense response of both treated roots and non-treated leaves of Gaoyou 115 was related to the time span of JA treatment and the concentration of JA. After treated with JA for 3-12 h, the gene expression of Bx9, PAL, PR-2a, MPI and FPS in treated roots was directly induced, resulting in an increase of DIMBOA content and a decrease of total phenol content, with the strongest induction effect detected at 100 μmol·L^-1 of JA, followed by at 50 μmol·L^-1, and at 10 μmol·L^-1 The induction effect weakened with time. Underground treatment with JA indirectly affected the chemical defense response of non-treated leaves. After underground treatment with 50μmol·L^-1 of JA for 3 h, the gene expression of Bx9 and FPS in non-treated leaves was induced, whieh caused a consequent increase of leaf DIMBOA content. Within 6-24 h of JA treatment, the gene expression of Bx9, PAL, PR-1, MPI and TPS in leaves was enhanced, while the Leaf DIMBOA and total phenol eontents were declined. For most of the parameters measured, the direct induction effect on roots was much more significant and started earlier than the indirect induction effect on leaves, and an inereasing trend was observed in the induction effect with increasing JA concentration.