ABSTRACT
Lipids are major and vital cellular constituents. In plants, stored lipids reserves play an important role in the life cycle by providing carbon and energy equivalents for periods of active metabolism (Graham 2008; Murphy 2012). For most eukaryotes, the preferred storage compounds are lipids in the form of triacylglycerols (TAGs), which are non-polar and can be stored in a nearly anhydrous form. Plants accumulate the storage lipids in specialized organelles called oil bodies (OBs), lipid bodies, lipid droplets or oil globules (Murphy 2012). These organelles have been found in different sporophytic plant organs and tissues, like oil seeds and oleaginous fruits (Huang 1994) as well as in cells of both, male (Piffanelli et al. 1998; Rodríguez-García et al. 2003; Zienkiewicz et al. 2010) and female gametophyte (Wu et al. 1999; Jiang et al. 2009). However, despite the obvious presence of OBs in pollen grains of different species (Fig. 1) little is known about the behaviour, breakdown
Figure 1. Nile red staining of OB (bright spots in the cytoplasm) in mature and germinating pollen of Arabidopsis thaliana (A and B) and in pollen tube of olive (Olea europaea L.) (C), and lily (Lilium longifl orum) (D). Numerous OBs fi lls up the cytoplasm of mature pollen grain (A). During in vitro pollen germination OBs are visible in the cytoplasm along the whole length of the pollen tube (B-D). Bar = 10 µm.
