Soybean and Bees

tra floral nectar (EFN) attracts ants, parasitoids and generalist predators, and serves as an
indirect defense against herbivores for more than 100 families of ferns, gymnosperms and
angiosperms (Koptur, 1992; Heil, 2008). Many plants produce nectar in diurnal rhythms,
partially adapted to consumer activity (Heil et al., 2000; Kuo and Pate et al., 1985; Tilman,
1978; Corbet and Delfosse, 1984).
Heil (2011) mentions that even though it is not known whether plants really can adjust the de
novo nectar secretion, a reabsorption of FN has been shown unambiguously (Nepi and Stpiczynska,
2008). Using different methods, Pederson et al. (1958) and Ziegler and Lütge (1959)
demonstrated the uptake and allocation to other plant organs, including labelling studies of
artificially applied 14 C-labelled sucrose or glutamine. The reabsorption of non-consumed FN
is apparently common, though this phenomenon has yet to be demonstrated for EFN (Nepi
and Stpiczynska, 2008).
The reabsorption of non-secreted nectar by the post-secretory floral nectary has been related
to programmed cell death in the nectary tissue, in combination with a phloem that
remains active and the resulting changes in source-sink relationships (Gaffal et al., 2007;
Kuo and Pate et al., 1985). Under this scenario, extra floral nectaries are likely to lack the
capacity to reabsorb nectar, because the regulation of EFN secretion is not dependent on ontogenetically
programmed patterns.
Nectar composition, dynamics and role
Nectar is a sweet liquid but, as an average, nectar sugars represents less than 2% of
the current net photosynthesis of a given time (Pate et al., 1985). Plants regulate
nectar production according to the consumption rates (Corbet and Delfosse, 1984;
Bolten et al., 1979; Inouye et al., 1980; Corbet et al., 1979; Gill, 1988; Pyke, 1981;
Pederson et al., 1958; roberts, 1977) and reabsorbs the exceeding (Pacini, 2003).
Heil et al. (2000, 2007) and Nepi and Stpiczynska (2008) refer that it is still partially unclear
where non-carbohydrate nectar components are synthesized, how its compounds
enter the nectar, how plants adapt nectar secretion to consumption rates or consumer
identity, and also how non-consumed nectar is reabsorbed. Despite Gonzales-Teuber and
Heil (2009a, b) and Nicolson et al. (2007) have mentioned that little is known about nectar
components other than sugars and amino acids, and also about synthesis of nectar
components and the regulation of their secretion, important discoveries were recently
made. Nectar proteins, called nectarins, were identified in tobacco (Nicotiana spp.) FN
60 SoybeAn and bees