Davis A R, Pylatuik J D, Paradis J C, Low N H
Department of Biology, University of Saskatchewan, Saskatoon, Canada.
Planta. 1998 Jun;205(2):305-18. doi: 10.1007/s004250050325.
Nectar-carbohydrate production and composition were investigated by high-performance liquid chromatography and enzymology in nine species from five tribes of the Brassicaceae. In six species (Arabidopsis thaliana (L.) Heynh., Brassica napus L., B. rapa L., Lobularia maritima (L.) Desv., Raphanus sativus L., Sinapis arvensis L.) that produced nectar from both lateral nectaries (associated with the short stamens) and median nectaries (outside the long stamens), on average 95% of the total nectar carbohydrate was collected from the lateral ones. Nectar from these glands possessed a higher glucose/fructose ratio (usually 1.0-1.2) than that from the median nectaries (0.2-0.9) within the same flower. Comparatively little sucrose was detected in any nectar samples except from Matthiola bicornus (Sibth. et Sm.) DC., which possessed lateral nectaries only and produced a sucrose-dominant exudate. The anatomy of the nectarial tissue in nectar-secreting flowers of six species, Hesperis matronalis L., L. maritima, M. bicornus, R. sativus, S. arvensis, and Sisymbrium loeselii L., was studied by light and scanning-electron microscopy. Phloem alone supplied the nectaries. However, in accordance with their overall nectar-carbohydrate production, the lateral glands received relatively rich quantities of phloem that penetrated far into the glandular tissue, whereas median glands were supplied with phloem that often barely innervated them. All nectarial tissue possessed modified stomata (with the exception of the median glands of S. loeselii, which did not produce nectar); further evidence was gathered to indicate that these structures do not regulate nectar flow by guard-cell movements. The numbers of modified stomata per gland showed no relation to nectar-carbohydrate production. Taken together, the data on nectar biochemistry and nectary anatomy indicate the existence of two distinct nectary types in those Brassicacean species that possess both lateral and median nectaries, regardless of whether nectarial tissue is united around the entire receptacle or not. It is proposed that the term "nectarium" be used to represent collectively the multiple nectaries that can be found in individual flowers.
通过高效液相色谱法和酶学方法，对十字花科五个族的九个物种的花蜜碳水化合物产量和组成进行了研究。在六个物种（拟南芥（L.）Heynh.、甘蓝型油菜L.、白菜L.、海滨香豌豆（L.）Desv.、萝卜L.、野芥菜L.）中，它们从侧蜜腺（与短雄蕊相关）和中蜜腺（在长雄蕊外侧）都分泌花蜜，平均而言，总花蜜碳水化合物的95%是从侧蜜腺收集的。同一朵花中，这些腺体分泌的花蜜的葡萄糖/果糖比值（通常为1.0 - 1.2）高于中蜜腺分泌的花蜜（0.2 - 0.9）。除了双角紫罗兰（Sibth. et Sm.）DC.外，在任何花蜜样品中检测到的蔗糖都相对较少，双角紫罗兰只有侧蜜腺，分泌以蔗糖为主的渗出物。通过光学显微镜和扫描电子显微镜研究了六个物种（香水花L.、海滨香豌豆、双角紫罗兰、萝卜、野芥菜、粗糙亚麻荠L.）分泌花蜜的花朵中蜜腺组织的解剖结构。仅韧皮部为蜜腺提供养分。然而，根据它们总的花蜜碳水化合物产量，侧蜜腺接收相对丰富的韧皮部供应，这些韧皮部深入腺体组织，而中蜜腺得到的韧皮部供应往往很少，几乎无法为其提供养分。所有蜜腺组织都有特化的气孔（粗糙亚麻荠的中蜜腺除外，它不分泌花蜜）；进一步的证据表明，这些结构不会通过保卫细胞运动来调节花蜜流动。每个腺体特化气孔的数量与花蜜碳水化合物产量无关。综合花蜜生物化学和蜜腺解剖学数据表明，在那些同时拥有侧蜜腺和中蜜腺的十字花科物种中，存在两种不同类型的蜜腺，无论蜜腺组织是否围绕整个花托联合在一起。建议使用“蜜腺群”一词来统称在单个花朵中发现的多个蜜腺。
