Expression of β-galactosidase and β-xylosidase genes during microspore and pollen development

Tobacco (Nicotiana tabacum L.) microspores at the time of mitosis are characterized by the abundant occurrence of 92- and 98-kDa glycoproteins (GP92 and GP98). GP92 is a soluble protein while GP98 is bound to the insoluble microspore fraction. Both glycoproteins were isolated by affinity chromatography and SDS–PAGE and analysed by MS. Peptide sequences were determined by μ-HPLC/nano-ESI–MS/MS (electrospray ionization tandem MS). GP92 displayed...