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兰科玉凤花属夜间蛾类传粉研究取得新进展

  植物花部性状与传粉昆虫体型和行为特征的匹配是植物与传粉动物协同进化的基础。夜间传粉为重要的传粉综合征之一,达尔文著名的彗星兰和天蛾喙长的协同进化就是夜间传粉综合征的典型案例。然而,在我国夜间传粉研究处于初始阶段,而蛾类传粉在高海拔地区有花植物中的重要性和作用机制尚不清楚。 

  近年来中国科学院昆明植物研究所植物多样性演化和生态适应团队王红研究组在滇西北开展了夜间蛾类传粉的系统研究。选取丽江玉龙雪山分布的兰科宽药隔玉凤花(Habenaria limprichtii)为对象,发现其繁育系统为自交亲和,然而自交授粉处理的果实具胚种子的比例极显著低于异交授粉,呈现出明显的自交衰退。该种植物缺乏自动自交机制,其繁殖成功依赖于昆虫,且为访花昆虫提供花蜜报酬。宽药隔玉凤花的传粉昆虫为夜蛾科的莴苣冬夜蛾(Cucullia fraterna)和中金翅夜蛾(Trichoplusia intermixta),以及天蛾科的红天蛾(Deilephila elpenor)。两种夜蛾具有较短的喙,花粉块较少携带在足上。红天蛾具有较长的喙并在复眼上携带较多的花粉块。值得关注的是,该种植物的花气味具有大量芳香气味的苯环型化合物,在傍晚19:00后开始释放。研究表明该花气味是蛾类的主要吸引信号,访花昆虫的活动时间与夜间花气味释放时间较为一致,主要集中在19:30 – 21:30经形态性状分析显示红天蛾的喙长与宽药隔玉凤花花距长相等;花粉块粘盘之间宽度与两个复眼之间的距离也相等。因此,该研究揭示了传粉昆虫与兰科植物典型的形态特征演化匹配模式。研究为生物多样性热点地区高山分布的兰科植物夜间蛾类传粉和协同演化的深入理解提供了重要的线索。 

  昆明植物所博士研究生陶至彬为该论文第一作者,王红研究员和任宗昕副研究员为通讯作者。相关研究以Nocturnal hawkmoth and noctuid moth pollination of Habenaria limprichtii (Orchidaceae) in sub-alpine meadows of the Yulong Snow Mountain (Yunnan, China)为题发表在国际著名植物学刊物Botanical Journal of the Linnean Society上。该研究得到科技部重大研究计划项目(2014CB954100)和国家自然科学基金-云南省联合基金重点项目(U1502261)等的支持。

Abstract
Habenaria (Orchidaceae) is a species-rich genus, usually pollinated by members of Lepidoptera, but the pollination ecology of its sub-alpine species in the Himalayas remains under-explored. We focused on three populations of the endangered, nectar-secreting H. limprichtii on Yulong Snow Mountain (eastern Himalayas). Results showed that spurs of H. limprichtii contained 10.8 μl of nectar with 26.3% dissolved sugars at night. A hawkmoth (Deilephila elpenor subsp. lewisii) and two species of settling moths (Cucullia fraterna and Trichoplusia intermixta) were the dominant pollinators. The hawkmoths had long proboscides (26.3 mm in length), matching the spur length of the flowers, and carried one to 30 pollinaria on their eyes. In contrast, settling moths had short proboscides (15–16.4 mm) carrying fewer than nine pollinaria on their legs or thoraces. These insects may have been attracted by the floral scent dominated by two aromatic benzenoid compounds. Flowers are self-compatible, but pollinators were required to produce fruits. Hand-pollination experiments showed a high level of inbreeding depression (a low proportion of seeds with well-developed embryos in self-pollinated fruits), whereas insect-mediated (natural) rates of cross-pollination were also low (13%). This suggests that most fruits were fertilized following moth-mediated autogamy/geitonogamy. Fruit set was always higher than the rate of pollinaria removal, suggesting a higher pollination efficiency due to its sectile and friable pollinia. Fruit set in natural populations was highly variable among years (28.5–93.7%), doubling in 2016. Although this is only the fourth case of moth-pollination described in Chinese Habenaria spp., it highlights the potential importance of this syndrome at higher elevations.
Keywords:Himalaya, pollinarium removal, reproductive success, Sphingidae

 

  

 

1 宽药隔玉凤花及其夜间传粉昆虫 

 

2 宽药隔玉凤花人工自交和异交授粉,以及自然对照种子胚发育比较 

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