Flow cytometry of isolated chloroplasts and thylakoids

This paper describes the first flow cytometric measurements on plant leaf subcellular organelles. Intact chloroplasts and thylakoid membrane preparations from spinach and maize were assayed for forward and oblique light scatter and fluorescence emission. Chloroplast preparations showed at least two subgroups distinguished on light scatter and fluorescence, but thylakoid preparations had distinctly different properties. The fluorescence measured with single laser excitation was the constant yield component, F 0 . The variable fluorescence, F v , was detected by a dual laser technique. While the two types of spinach chloroplasts were almost identical in pigmentation, two of the maize mesophyll subgroups were quite different showing well separated emission maxima in the 685 and 710 nm bands.