PDF(Pubmed)
Abstract：
BACKGROUND: Floral nectar is the most common reward flowers offered to pollinators. The quality and quantity of nectar produced by a plant species provide a key to understanding its interactions with pollinators and predicting rates of reproductive success. However, nectar secretion is a dynamic process with a production period accompanied or followed by reabsorption and reabsorption remains an understudied topic. In this study, we compared nectar volume and sugar concentration in the flowers of two long-spurred orchid species, Habenaria limprichtii and H. davidii (Orchidaceae). We also compared sugar concentration gradients within their spurs and rates of reabsorption of water and sugars.
RESULTS: Both species produced diluted nectar with sugar concentrations from 17 to 24%. Analyses of nectar production dynamics showed that as flowers of both species wilted almost all sugar was reabsorbed while the original water was retained in their spurs. We established a nectar sugar concentration gradient for both species, with differences in sugar concentrations at their spur\'s terminus and at their spur\'s entrance (sinus). Sugar concentration gradient levels were 1.1% in H. limprichtii and 2.8% in H. davidii, both decreasing as flowers aged.
CONCLUSIONS: We provided evidence for the reabsorption of sugars but not water occurred in wilted flowers of both Habenaria species. Their sugar concentration gradients vanished as flowers aged suggesting a slow process of sugar diffusion from the nectary at the spur\'s terminus where the nectar gland is located. The processes of nectar secretion/reabsorption in conjunction with the dilution and hydration of sugar rewards for moth pollinators warrant further study.
RESULTS: Both species produced diluted nectar with sugar concentrations from 17 to 24%. Analyses of nectar production dynamics showed that as flowers of both species wilted almost all sugar was reabsorbed while the original water was retained in their spurs. We established a nectar sugar concentration gradient for both species, with differences in sugar concentrations at their spur\'s terminus and at their spur\'s entrance (sinus). Sugar concentration gradient levels were 1.1% in H. limprichtii and 2.8% in H. davidii, both decreasing as flowers aged.
CONCLUSIONS: We provided evidence for the reabsorption of sugars but not water occurred in wilted flowers of both Habenaria species. Their sugar concentration gradients vanished as flowers aged suggesting a slow process of sugar diffusion from the nectary at the spur\'s terminus where the nectar gland is located. The processes of nectar secretion/reabsorption in conjunction with the dilution and hydration of sugar rewards for moth pollinators warrant further study.
摘要：
背景：花花蜜是提供给传粉者的最常见的奖励花。植物产生的花蜜的质量和数量为了解其与传粉媒介的相互作用和预测繁殖成功率提供了关键。然而,花蜜分泌是一个动态过程，其产生期伴随着或随后再吸收，再吸收仍然是一个未被研究的话题。在这项研究中,我们比较了两种长期刺激的兰花花的花蜜体积和糖浓度，哈伯纳氏菌和H.davidii（兰科）。我们还比较了它们的刺中的糖浓度梯度以及水和糖的重吸收速率。
结果：两种物种都产生了糖浓度为17％至24％的稀释花蜜。对花蜜生产动力学的分析表明，随着这两个物种的花朵枯萎，几乎所有的糖都被重新吸收，而原始的水保留在它们的刺中。我们建立了两个物种的花蜜糖浓度梯度，在他们的骨刺末端和骨刺入口（窦）的糖浓度不同。糖浓度梯度水平在H.limprichtii和H.davidii中分别为1.1%和2.8%。两者都随着花朵的老化而减少。
结论：我们提供了在两种Habenaria物种的枯萎花中重新吸收糖而不是水的证据。随着花朵的老化，它们的糖浓度梯度消失了，这表明糖从蜜腺所在的刺末端的蜜腺扩散过程缓慢。花蜜分泌/再吸收的过程以及对蛾传粉媒介的糖奖励的稀释和水合作用值得进一步研究。
结果：两种物种都产生了糖浓度为17％至24％的稀释花蜜。对花蜜生产动力学的分析表明，随着这两个物种的花朵枯萎，几乎所有的糖都被重新吸收，而原始的水保留在它们的刺中。我们建立了两个物种的花蜜糖浓度梯度，在他们的骨刺末端和骨刺入口（窦）的糖浓度不同。糖浓度梯度水平在H.limprichtii和H.davidii中分别为1.1%和2.8%。两者都随着花朵的老化而减少。
结论：我们提供了在两种Habenaria物种的枯萎花中重新吸收糖而不是水的证据。随着花朵的老化，它们的糖浓度梯度消失了，这表明糖从蜜腺所在的刺末端的蜜腺扩散过程缓慢。花蜜分泌/再吸收的过程以及对蛾传粉媒介的糖奖励的稀释和水合作用值得进一步研究。
