TISSUE- AND CELL-SPECIFIC DISTRIBUTION OF CONNEXIN-32-RELATED AND CONNEXIN-26-RELATED PROTEINS FROM VICIA-FABA L

Different tissues (leaf lamina and mid-veins, epidermis, primary roots , etiolated shoots, hypocotyl, petioles) and protoplasts from mesophyl l, guard cells, and petioles of Vicia faba L., obtained from defined d evelopmental stages were analyzed with polyclonal antibodies raised ag ainst mouse liver connexins 26 and 32. Immunostaining after treatment with CX 26 antibodies showed two polypeptides of 21 and 16 kD in all t issues examined except for hypocotyl and epidermis. Additionally, a st ronger immunoresponse at 40 kD occurred in extracts from leaf material , mesophyll protoplasts, and roots. Incubation with the CX 32 antibodi es resulted in an immunoreactive band at 29 kD in mesophyll protoplast samples, and, a very weak band in extracts from leaf material. A 36 k D polypeptide, present in samples prepared from root, etiolated shoots , petioles, and midveins, did not appear in leaf laminas and mesophyll protoplasts. Extracts from guard cells did not show any immunoreactiv e band. The tissue- and cell-specific distribution of CX 23- and CX 26 -related proteins is supposed to reflect diversities in physiological functions together with alterations in plasmodesmatal ultrastructures during development.