Zhang, Xiaohui , Sawhney, Vipen , Davis, Arthur .
Nectar production and the anatomy and ultrastructure of the trichome-bearing floral nectary disk of Salvia farinacea (Lamiaceae).
Light, scanning- and transmission-electron microscopy were utilized to study the floral nectary in plants of Salvia farinacea var. Victoria Blue and especially var. Evolution, under greenhouse conditions. The floral nectary of this mint species is unusual in its possession of multicellular secretory trichomes on the concealed but prominent, cream-coloured nectary disk that surrounds the four naked ovules at the base of the gynoecium. Abaxially, the disk was prolonged into a tongue-like projection that exceeded ovule height and bore further trichomes on its upper surface (adaxial side), but modified stomata (most common on nectaries of the Lamiaceae) occurred exclusively on the lower surface (abaxial side) of the nectary projection. Histochemical staining with Sudan dyes demonstrated that these hairs interspersed on the nectary disk and upper surface of the projection produced oil droplets that collected below the distended cuticle of each trichome. In contrast, a carbohydrate-rich nectar droplet accumulated at the base of the corolla tube opposite the stomatal pores on the lower projection surface, for up to 8 days post-anthesis. Internally, the nectary projection received vascular strands consisting of both xylem and phloem, which apparently supply reserves for both oil and nectar production. Nectary parenchyma cells were rich in mitochondria and had clustered plastids with few starch grains, whereas endoplasmic reticulum (ER) was sparse. This study represents the first ultrastructural investigation wherein both oil-secreting trichomes and modified stomata co-exist within the floral nectary epidermis of a mint species.
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1 - Shaanxi Normal University, College of Life Sciences, Xi'an, 710062, China
2 - UNIVERSITY OF SASKATCHEWAN, Department Of Biology, 112 SCIENCE BLDG, SASKATOON, SK, S7N 5E2, Canada
3 - UNIVERSITY OF SASKATCHEWAN, Department Of Biology, 112 SCIENCE PLACE, SASKATOON, SK, S7N 5E2, Canada
Presentation Type: Poster:Posters for Topics
Location: Battelle South/Convention Center
Date: Monday, July 9th, 2012
Time: 5:30 PM