爱玉子花序挥发物成分以及对其传粉小蜂的吸引作用

利用动态顶空吸附法和GC-MS分析,研究接受期以及传粉或产卵5d后爱玉子(Ficus awkeotsang)雌、雄隐头花序挥发物成分。研究结果表明:爱玉子隐头花序挥发物的组成成分复杂,种类繁多,主要成分是对传粉小蜂具有显著吸引作用的芳樟醇。组成雌、雄花序的接受期挥发物信号的化合物种类与数量不同,但两者之间的共有化合物却占花序挥发物总量的70%以上,且接受期雌、雄花序挥发物组成比例相似,小蜂无法通过花序挥发物信号的差异,区别雌、雄花序,从而支持"榕树雌、雄花序接受期挥发物存在相互模拟现象"的假说。爱玉子传粉(或产卵)前后花序挥发物信号发生变化,表现在花序在传粉(或产卵)后,一些挥发性化合物在榕果中消失或相对含量减少(如芳樟醇),有些化合物的相对含量增加(如苯甲酸甲酯),并出现新的化合物(如2-乙基己醇);在化合物组成上,萜类化合物相对含量下降,芳香族化合物、脂肪族化合物相对含量上升。嗅觉仪实验表明爱玉子接受期雌、雄花序挥发物对其传粉榕小蜂有极显著的吸引作用,而传粉(或产卵)5d后的雌、雄花序挥发物对传粉榕小蜂有显著的趋避作用。传粉小蜂对雌、雄接受期花序挥发物的选择没有偏向性。榕果通过挥发物的释放量和成分的改变反映出花发育与被授粉(被产卵)状况,传粉小蜂通过接收榕果发出的化学信息,判断选择适合的寄主。研究对于爱玉子的高产栽培以及植物与昆虫专性共生化学生态学机制的理论研究具有重要的意义。

Volatile compounds from the syconia of Ficus awkeotsang Makino and their attractiveness to pollinator wasps

Volatile compounds from the female/male syconia of Ficus awkeotsang Makino in the receptive phase and on the fifth day after pollination/parasitization were collected by dynamic headspace adsorption and analyzed by gas chromatography\|mass spectrometry (GC\|MS). The results showed that the volatile compound profiles of figs were complex, consisting of various compositions; the main component was linalool, which significantly attracts wasps. Although the numbers and types of volatile compounds from male and female syconia proved to be different in the receptive phase, more than 70% of the total were common with similar proportions between them, making fig wasps unable to distinguish them according to their volatile compounds, This supports the hypothesis that the volatile compounds of male and female syconia simulate each other in the receptive phase. The volatile compound profiles of figs changed after pollination/parasitization, with some components disappeared or reduced in amounts (e.g. linalool), while some others increased in amount (e.g. benzoic acid, methyl ester) and some new compositions emerged (e.g. 1\|hexanol, 2\|ethyl\|). Generally, the relative content of terpenes decreased, while that of benzenoids and fatty acid derivatives increased. Olfactometer experiments showed that the volatile compounds of female and male syconia in receptive phase significantly attracted pollinating wasps, while those in the phase of 5 days after pollination or parasitization exhibited significant repellent effect on pollinating wasps. Pollinating wasps displayed similar preference to female and male receptive syconia. The changes in quantity and composition of the volatile compounds could reflect the situations of flower development and pollination or oviposition, which would help pollinating wasps to choose the proper hosts. The results would be of great significance on the high\|yield cultivation of F. awkeotsang and the theoretical study on the mechanism of chemical ecology of species\|specific mutualisms between fig and their pollinating wasps.