AN EVOLUTIONARY STUDY OF CHLOROPHYLL BIOSYNTHETIC HETEROGENEITY IN GREEN PLANTS

Chlorophyll biosynthetic heterogeneity among plant species was investi gated to determine the stability of a greening group within a species, the effects of age and treatment with chemical compounds on greening groups, and possible relationships of chlorophyll heterogeneity with e xisting classification schemes. Green plants exhibited one of three di fferent greening groups, depending upon the chlorophyll biosynthetic r oute that is used to form monovinyl (MV) or divinyl (DV) protochloroph yllides. Algae, bryophytes, ferns, and gymnosperms belonged exclusivel y to the dark divinyl-light divinyl (DDV-LDV) greening group. Angiospe rms exhibited all three greening groups. Most angiosperm species exami ned belonged to the dark monovinyl-light divinyl (DMV-LDV) greening gr oup, and several belonged to the DDV-LDV group. The dark monovinyl-lig ht monovinyl (DMV-LMV) greening group was rare and confined to derived groups in Cronquist's classification scheme. On the basis of these re sults, it is proposed that the DDV-LDV greening group is ancestral in green plants, the DMV-LMV group derived, and the DMV-LDV group evoluti onarily intermediate. However, within angiosperms, present data indica te that DMV-LDV is ancestral, DMV-LMV is advanced and DDV-LDV is secon darily derived.