CHLOROPLAST BIOGENESIS .77. TWO NOVEL MONOVINYL AND DIVINYL LIGHT-DARK GREENING GROUPS OF PLANTS AND THEIR RELATIONSHIP TO THE CHLOROPHYLL A BIOSYNTHETIC HETEROGENEITY OF GREEN PLANTS

摘要

On the basis of the steady-state accumulation of divinyl (DV) or monovinyl (MV) protochlorophyllide (Pchlide) a in darkness (D) or in the light (L), green plants have been classified into three different greening groups namely dark divinyl-light divinyl (DDV-LDV), dark monovinyl-light divinyl (DMV-LDV) and dark monovinyl-light monovinyl (DMV-LMV) (Ionannides et al., Biochem, Syst, Ecol. 22, 211-220, 1994), Interruption of the L phase of the photoperiod by a brief period of darkness (LD condition) revealed a predominance of different chlorophyll (Chi) a biosynthetic routes, depending upon the greening group affiliation of the plant species, For example, in DMV-LDV and DMV-LMV plants, the predominant Chi a biosynthetic routes under the :LD condition appear to be the Rn Chi a biosynthetic route and/or a mixed DV-MV Chi a biosynthetic route that bifurcates at the level of DV Pchlide a, On the basis of DV and MV Pchlide a accumulation rates after re-darkening, this greening group is designated as a light-dark MV (LDMV) subgroup, In DDV-LDV plants, the predominant LD Chi a biosynthetic routes appear to be the DV Chi a biosynthetic route and/or a mixed DV-MV Chi a biosynthetic route that bifurcates at the level of DV Chlide a, This greening group is designated as a light-dark DV (LDDV) subgroup, It is proposed that upon inhibiting the conversion of Pchlide a to Chi a by interruption of the L phase of the photoperiod by a brief period of D, the rates of DV and MV Pchlide a regeneration may reflect the carryover rates of DV and MV Pchlide a biosynthesis in L instead of reflecting a differential use of DV :and MV carboxylic biosynthetic rates in D, It is also shown that in LDMV plants, MV Chlide a and MV Chi a are formed without the participation of [4-vinyl] Chlide a reductase, On the basis of recently published evidence, it is also argued that Pchlide oxidoreductase-A (FOR-A) may be active in LDDV plants, while POR-B may predominate in LDMV plant species. The evolutionary significance of the LDDV and LDMV greening subgroups is discussed. [References: 38]