中科院西双版纳植物园博士研究生陈春在导师宋启示的指导下,与法国有关研究人员合作,通过分析榕树隐头花序挥发物和检测榕小蜂对挥发物的行为反应,发现了罕见的榕树通过释放单一的不常见挥发性化合物,达到对其传粉榕小蜂的专性吸引,以确立榕树与榕小蜂间专一性的共生关系。
该项研究发现4-甲基苯甲醚在雌雄异株的鸡嗉子榕Ficus semicordata的开放期隐头花序挥发物中占主导地位(94-98%),并在隐头花序授粉或寄生4天后完全消失,且不存在于其它榕树的花序挥发物中。生物检测发现4-甲基苯甲醚对鸡嗉子榕小蜂Ceratosolen gravelyi有吸引作用,而不含对甲基苯甲醚的其它榕树的花序挥发物则无此吸引作用。
研究结果表明4-甲基苯甲醚,一种不常见的榕树挥发性化合物,确定了对鸡嗉子榕传粉者的专一性吸引,建立了一种独特的榕树/榕小蜂专一性共生关系。该项研究结果已在权威生态学杂志FUNCTIONAL ECOLOGY网上发表。
榕树与榕小蜂间形成了生物界典型的专一性共生关系,一种榕树仅仅依赖于一种榕小蜂为其传粉,相应地,榕小蜂也只仰仗一种榕树为其提供繁殖后代的场所和食物。以前的研究表明榕树隐头花序的气味在榕树与榕小蜂间共生中起重要作用。(生物谷Bioon.com)
生物谷推荐原始出处:
Functional Ecology 5 Aug 2009 DOI:10.1111/j.1365-2435.2009.01622.x
Private channel: a single unusual compound assures specific pollinator attraction in Ficus semicordata
Chun Chen 1,? , Qishi Song 1,? , Magali Proffit 2,4 , Jean-Marie Bessière 3 , Zongbo Li 1 and Martine Hossaert-McKey*,2
1 Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, Yunnan 650223, China ; 2 Centre d'Ecologie Fonctionnelle et Evolutive (CEFE), UMR CNRS, Montpellier Cedex, France ; 3 Laboratoire de Chimie Appliquée, Ecole Nationale Supérieure de Chimie de Montpellier, Montpellier Cedex, France ; and 4 School of Biological and Conservation Sciences, University of KwaZulu-Natal, Scottsville, Pietermaritzburg, South Africa
1. Floral scents have been suggested to play a key role in the obligate pollination mutualism between figs and fig wasps. However, few studies have determined whether pollinator-attractive compounds could alone assure species-specificity ('private channel'), or whether specificity is mediated by more complex 'floral filters', of which scent is only one component.
2. We examined changes in the floral volatile compounds of Ficus semicordata, a dioecious fig species, during and after pollination using headspace collection and compound identification by Gas Chromatography/Mass Spectrometry (GC/MS). One benzenoid compound, 4-methylanisole, was strongly predominant (94–98%) among the volatile compounds emitted by both male and female receptive figs of F. semicordata, whereas it was totally absent in the volatiles emitted by figs 4 days after pollination, as well as in receptive-stage volatiles emitted by two other sympatric fig species, Ficus racemosa and Ficus hispida.
3. Bioassays using the specific pollinator of F. semicordata, Ceratosolen gravelyi, in a Y-tube olfactometer showed that 4-methylanisole was attractive to C. gravelyi in a wide range of concentrations (from 1·22 × 10?2 ng/100 μL to 1·22 × 106ng/100μL). Moreover, chemical blends lacking 4-methylanisole were unattractive to C. gravelyi. These non-active odour sources included volatile compounds emitted by receptive figs of the two other sympatric fig species and volatiles of F. semicordata post-pollination figs.
4. All these results suggest that 4-methylanisole is the main signal compound in the floral scent of F. semicordata that attracts its obligate pollinator to the host figs at the precise stage required for pollination and oviposition. Furthermore, the high proportion of 4-methylanisole in the odours of receptive figs of both sexes was consistent with the hypothesis of chemical mimicry in dioecious figs.
5. A simple signal comprised of one compound that is unusual among Ficus and that is an infrequent, usually minor, component of other floral odours, may thus function as a private channel in this specialized obligate mutualism.