常春油麻藤有气味花蜜及其生态功能

一些被子植物能够分泌有气味的花蜜,但这一自然现象很少被关注.作为嗅觉信号线索,有气味的花蜜可能是将访花者和气味信号结合在一起的特征,它与传粉者及盗蜜者的关系值得探索.本研究以常春油麻藤(Mucuna sempervirens)为对象,研究了其开花动态及泊氏长吻松鼠(Dremomys pernyi)和赤腹松鼠(Callosciurus erythraeus)的访花行为,采用顶空固相微萃取和气相色谱-质谱法收集并分析了花蜜的挥发物成分,探讨了花蜜对中华蜜蜂(Apis cerana cerana)的吸引作用及对酸臭蚁(Tapinoma sp.)的毒杀作用.结果表明:常春油麻藤花蜜释放的挥发物以脂肪族化合物为主(87.2％),其中酮类占56.1％,无含硫挥发性成分,这和该属其他蝙蝠传粉种类花蜜释放含硫化合物的结果不一致.此外,常春油麻藤的花蜜对酸臭蚁有慢性毒杀作用,而对中华蜜蜂则有吸引作用.未发现蝙蝠访花,但观察到泊氏长吻松鼠和赤腹松鼠可能为常春油麻藤传粉.因此,常春油麻藤可能不属于蝙蝠传粉的种类.希望本研究能为该属亚洲类群的传粉机制提供数据,并为其他植物类群花蜜成分及功能研究提供新的视角.

Scented nectar of Mucuna sempervirens and its ecological function

Scented nectar secreted by flowers is an interesting natural phenomenon in angiosperms that is often overlooked by most researchers.Scented nectar is an evolutionary feature coupling the behavior between flower-visitors and their rewards.The effect of scented nectar on pollinator or nectar-thief is a scientific problem which deserves further exploration.We evaluated Mucuna sempervirens flowering dynamics,floral nectar volatiles,behaviors of Dremomys pernyi and Callosciurus erythraeus to inflorescence opening,nectar’s attraction effect to Apis cerana cerana,and the toxic effect of M.sempervirens nectar to Tapinoma sp.Aliphatic compounds(87.2%) were the main volatiles in nectar of M.sempervirens,whereas ketones accounted for 56.1% of the total volatiles.Lastly,volatile components with sulfur elements were absent from nectar samples.Previous studies of bat pollinated plant species have found that plants in the genus Mucuna always release sulfur compounds.Additionally,we found that the nectar of M.sempervirens was poisonous to Tapinoma sp.ant species,whereas it attracted A.cerana cerana using the Y olfactory bioassay.Squirrel species(D.pernyi and C.erythraeus) were effective pollinators of M.sempervirens,so we suspected that M.sempervirens might not be pollinated by bats only.This study provides data of pollinationmechanisms in Mucuna and provides a new perspective of composition and function study of nectar in other plant groups in future.