PROTOCHLOROPHYLL(IDE) FORMS IN HYPOCOTYLS OF DARK-GROWN BEAN (PHASEOLUS-VULGARIS)

The protochlorophyll(ide) forms and plastid ultrastructure were invest igated in hypocotyls of dark-grown seedlings of kidney bean (Phaseolus vulgaris L. cv. Brede zonder draad). By deconvolution of the fluoresc ence emission spectra into Gaussian components three protochlorophyll( ide) forms were found with maxima at 633, 642 and 657 nm, respectively . The ratio of protochlorophyll(ide) emitting at 657 nm to protochloro phyll(ide) emitting at 633 nm decreased downwards the hypocotyl. The g radient was established already after 4 days in dark-grown Phaseolus a nd was also seen in hypocotyls of 7-day-old dark-grown plants of 8 oth er species. Ultrastructural observations revealed a plastid developmen tal sequence along the hypocotyl. Plastids in the upper parts of the h ypocotyl contained prolamellar bodies typical of etiolated leaves whil e those in the lower parts contained only stroma lamellae. Immunologic al detection of NADPH-protochlorophyllide oxidoreductase (EC 1.3.1.33) on nitrocellulose membranes after sodium dodecyl sulphate polyacrylam ide gel electrophoresis (SDS-PAGE) indicated the occurrence of the enz yme in upper, middle and lower sections of hypocotyls and in the root tips.