LOCALIZATION OF THE FE(III)-ZN(II) PURPLE ACID-PHOSPHATASE IN DRY KIDNEY BEANS USING IMMUNOFLUORESCENCE AND IMMUNOGOLD ELECTRON-MICROSCOPY

Localization of purple acid phosphatase (PAP) from the seeds of kidney beans, Phaseolus vulgaris (L.), was performed using light and transmi ssion electron microscopy. After rehydration and aqueous fixation, cry o-sections of bean cotyledon tissue showed a bright immunofluorescent signal in the cytoplasm of cells whereas cell walls and reserve materi als (starch, protein bodies) remained unstained. In ultrathin sections of dry cotyledon tissue anhydrously fixed in acrolein vapour and embe dded in Lowicryl resin, PAP mapped exclusively to ribosome-rich areas of the cytoplasm. In view of these results, we propose that kidney bea n PAP might possibly be engaged in mechanisms involved in the triggeri ng of seed dormancy. (C) 1998 Annals of Botany Company.