伤害诱导普通白木香与奇楠种质沉香中倍半萜类成分及早期倍半萜合酶基因表达的差异分析

目的 明确伤害诱导普通白木香和奇楠种质所结沉香中倍半萜组分及其早期倍半萜合酶基因表达模式的差异。方法 采用气相色谱-质谱法（GC-MS）分析普通沉香和奇楠沉香中倍半萜组分的差异；对3年生普通白木香和奇楠种质茎干分别进行全断干伤害，采用实时荧光定量聚合酶链式反应（qRT-PCR）分析伤害早期倍半萜合酶基因AsTPS2、AsTPS13、AsTPS14、AsTPS17、AsTPS18、AsTPS20、AsTPS23表达模式的差异。结果 奇楠沉香倍半萜组分显著不同于普通白木香所结沉香，2种沉香中分别检测到16、17个倍半萜成分，其中共有成分12个，且共有成分含量差异较大；两者的倍半萜合酶基因在伤害诱导早期表达模式也不同，伤害诱导24 h内，普通白木香中7个倍半萜合酶基因表达水平均上升，2 h达到最大值后下降，而奇楠种质中AsTPS2、AsTPS13、AsTPS14、AsTPS17和AsTPS23基因表达量在24 h内持续上升，AsTPS20基因表达量在6 h达到最大值，但AsTPS18基因表达量低，在伤害诱导0~24 h变化不明显，显著低于普通白木香种质。结论 普通白木香与奇楠种质所结沉香倍半萜类成分差异明显，且响应伤害诱导的倍半萜合酶基因在0~24 h表达模式显著不同，推测倍半萜合酶基因的差异诱导表达可能是2种种质形成的倍半萜成分差异较大的原因之一。

Differences in Sesquiterpenes of Agarwood Produced in Aquilaria sinensis and Chi-Nan Germplasm and Sesquiterpene Synthase Gene Expression in the Early Stage of Wound Stress

Objective To determine the differences in sesquiterpenes of agarwood produced in Aquilaria sinensis and Chi-Nan germplasm and the expression patterns of sesquiterpene synthase genes in the early stage of wound stress.Methods The sesquiterpene compositions of agarwood produced in A. sinensis and Chi-Nan germplasm were analyzed by the gas chromatography-mass spectrometry (GC-MS). Three-year-old Aquilaria sinensis and Chi-Nan germplasm underwent stem cutting. The expression patterns of sesquiterpene synthase genes AsTPS2, AsTPS13, AsTPS14, AsTPS17, AsTPS18, AsTPS20, and AsTPS23 were detected by real-time fluorescence-based quantitative polymerase chain reaction (qRT-PCR).Results The sesquiterpene composition of agarwood in Chi-Nan germplasm was quite different from that in A.sinensis. Sixteen and 17 sesquiterpenes were detected in agarwood produced in two germplasms, including 12 common ones with greatly different content. The expression patterns of sesquiterpene synthase genes in the early stage of wound stress were also different in the two germplasms. Within 24 h after stem cutting, the expression levels of seven sesquiterpene synthase genes in A. sinensis all increased, peaked at 2 h, and then decreased. However, the expression levels of AsTPS2, AsTPS13, AsTPS14, AsTPS17, and AsTPS23 in Chi-Nan germplasm continued to rise within 24 h. The AsTPS20 expression level peaked at 6 h. The AsTPS18 expression level in Chi-Nan germplasm was low and almost unchanged within 24 h, which was significantly lower than that in A.sinensis.Conclusion The sesquiterpenes of agarwood in A. sinensis and Chi-Nan germplasm were significantly different, and the expression patterns of sesquiterpene synthase genes were also significantly different within 24 h of wound stress. It is inferred that different expression patterns of sesquiterpene synthase genes induced by wound stress presumedly result in the difference in sesquiterpene composition of agarwood produced in two germplasms.