Merging concepts: The role of self-assembly in the development of pollen wall structure

Experimental modelling of exine-like structures

“…According to Skvarla and Rowley (1987) and Rowley and Claugher (1991), early SP accumulation in the tetrad period is connected with SP-acceptor particles (SAPs). SAPs probably include enzyme molecules for SP polymerisation (Gabarayeva, 1993;Rowley et al, 1999) or they are centres of SP nucleation (Gabarayeva & Hemsley, 2006). They were found in a number of species in exine ontogeny (e.g.…”

“…-Abbreviations for all figures: c, callose; cg, composite gel; feo, fibrillar envelope of orbicule; fl, foot layer; g, glycocalyx; git, granular infratectum; in, intine; mc, microspore cytoplasm; o, orbicule; pm, plasma membrane; ps, periplasmic space; sl, supporting liquid; t, tectum; ta, tapetum. (Gabarayeva & Hemsley, 2006;Hemsley & Gabarayeva, 2007). The striking similarity of lifeless patterns (organo-metallic covers) and exine microarchitecture gives more evidence for such a suggestion (Hemsley & Gabarayeva, 2007, figure 1).…”

Sporoderm development inSwida alba(Cornaceae), interpreted as a self-assembling colloidal system

“…This sequence is well-known and widespread; in particular, it was observed in a number of species during our ontogenetic studies of remotely related taxa (Stangeria: Gabarayeva & Grigorjeva, 2002;Cabomba: Gabarayeva et al, 2003;Trevesia: Gabarayeva et al, 2009a;Chamaedorea: Gabarayeva & Grigorjeva, 2010; Persea and Acer: Gabarayeva et al, 2010aGabarayeva et al, , 2010b. The explanation for this is probably our previous hypothesis (Gabarayeva & Hemsley, 2006;Hemsley & Gabarayeva, 2007). According to this hypothesis, growth of the exine occurs by successive transitory pseudophases (= mesophases) of a self-assembling micellar colloid system in the constrained volume of the periplasmic space.…”

“…Our aim in this study is, after detailed investigation with TEM of the sequence of developmental events during sporoderm development of Swida alba, to determine if the data obtained confirm the idea that was put forward earlier (Gabarayeva & Hemsley, 2006;Hemsley & Gabarayeva, 2007). The essence of that hypothesis was the supposition of a considerable role of micelle self-assembly processes in sporoderm development of any species.…”

“…It is important to stress that fluff-like material always bears dark particles, referred to as sporopollenin acceptor particles (SAPs: Skvarla & Rowley, 1987;Rowley et al, 1995Rowley et al, , 1999 and then interpreted as sporopollenin receptors (Gabarayeva et al, 1998) or centres of sporopollenin nucleation (Gabarayeva & Hemsley, 2006). In the taxonomically remote genus Cabomba (Gabarayeva et al, 2003), SAPs are also responsible for the appearance of striae on the distal tips of columellae and for further growth and differentiation of the initial striae into macro-and micro-striae.…”