中文摘要：

以黄芩为实验材料,利用PCR克隆了其异分支酸合成酶（Isochorismate synthase,ICS）基因的部分编码序列,利用该序列构建了病毒诱导的基因沉默（Virus induced gene silence,VIGS）载体p TRV2-VIGSics,对黄芩ICS基因进行了沉默;测定了沉默后ICS基因的表达水平及ICS酶活性,研究了ICS基因沉默对黄芩水杨酸（Salicylic acid,SA）含量的影响,以及干旱胁迫对沉默材料ICS基因表达水平、酶活性和SA含量的影响。结果表明VIGS沉默处理使ICS表达水平显著降低,为对照组的25%,ICS酶活性未检测到,黄芩SA含量为对照组的44.4%;干旱胁迫下ICS表达水平和酶活性有所恢复,分别为对照组的87%和4.95%,黄芩SA含量没有恢复,而是降低至了对照组的13.2%。

英文摘要：

We cloned partial coding sequences of isochorismate synthase（ ICS） gene in Scutellaria baicalensis Georgi,and constructed the virus induced gene silence（ VIGS） vector,p TRV2-VIGSics. ICS gene was silenced by VIGS technique. We analyzed the ICS activity,expression level,and salicylic acid content of the silenced seedlings. ICS silence resulted in the drastically reduction of the expression level,enzyme activity and salicylic acid content in S. baicalensis Georgi. The enzyme activity was not detected,the expression level was reduced to25%,and salicylic acid content was reduced to 44. 4%. While,drought stress caused the expression level and enzyme activity recovered to 87% and 4. 95%,respectively. Instead of recovery,the salicylic acid content was further reduced to 13. 2% of the wild type level under drought stress.