N-glycoproteins specific for different stages of microspore and pollen development in tobacco

Glycoproteins (GPs) specifically linked to stages of microspore and pollen development were identified and characterized by: 1D- and 2D-electrophoresis, treatment with glycosidases, affinity blotting with lectins ConA, GNA, AAA, WGA, DSA; PNA and RCA, and according to cell location. Most GPs reacted with ConA and GNA and were hydrolyzed with PNGase F and endoglycosidase H, indicating N-linkage of high-mannose and/or hybrid type glycans. Early microspores were unique by the occurrence of ConA and AAA binding 50- and 52-kD GPs. Specific for mitotic microspores were cytoplasmic neutral GPs 39 and 92 kD, and membrane GP 98 kD. Maturing pollen was characterized by a new set of ConA-binding GPs: acidic, membrane GP 38 kD, neutral GPs 51, 66 and 75 kD, GP 53 kD separated in IEF into spots with pi 6.8-7.5 and 5.9, and IEF variants of GP 55 kD with pi 6.5-7.5, GPs 48, 59, 70, 83 and 114 kD showed developmental changes in reactivity with various lectins. In contrast to GPs, no clear qualitative changes were observed in profiles of Coomassie blue stained proteins during pollen development. The oligosaccharide structures appeared as important determinants of specificities of GPs associated with phases of microspore and pollen development. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.