Floral nectar reabsorption and a sugar concentration gradient in two long-spurred Habenaria species (Orchidaceae)

BMC Plant Biology

Research

Shi-Jia Wen¹  Hai-Ping Zhang²  Zong-Xin Ren³  Hong Wang³ 

[1] Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 650201, Kunming, China;College of Forestry, Hainan University, 570228, Haikou, China;Jiangxi Key Laboratory of Plant Resources and Biodiversity, Jingdezhen University, 334000, Jingdezhen, China;Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 650201, Kunming, China;University of Chinese Academy of Sciences, Beijing, China;Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 650201, Kunming, China;University of Chinese Academy of Sciences, Beijing, China;Yunnan Lijiang Forest Biodiversity Observation and Research Station, 674100, Lijiang, China;

关键词: Nectar production;    Nectar volume and concentration;    Nectar reabsorption;    Floral rewards;    Flower age;   

DOI  :  10.1186/s12870-023-04344-2

 received in 2023-03-11, accepted in 2023-06-11,  发布年份 2023

来源: Springer

【 摘 要 】

BackgroundFloral 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.ResultsBoth 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.ConclusionWe 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.

【 授权许可】

CC BY   
© The Author(s) 2023

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