Light-Dependent Accumulation of Radiolabeled Plastid-Encoded Chlorophyll a-Apoproteins Requires Chlorophyll a: I. Analysis of Chlorophyll-Deficient Mutants and Phytochrome Involvement. Academic Article uri icon

abstract

  • The accumulation of radiolabeled plastid-encoded chlorophyll a-apoproteins is light dependent and is controlled at a posttranscriptional level. Illumination of dark-grown barley (Hordeum vulgare L.) with a brief pulse of red light induced the accumulation of radiolabeled chlorophyll a-apoproteins in subsequent protein synthesis assays. The induction of radiolabeled chlorophyll a-apoprotein accumulation was not affected by pretreatment of leaves with cycloheximide. Fluence response studies showed that a red light photoreceptor controls the accumulation of radiolabeled chlorophyll a-apoproteins with a threshold fluence of approximately 50 to 100 microeinsteins per square meter. While red light initiated chlorophyll a-apoprotein accumulation, this process was not reversed by a far red light treatment given immediately after the pulse of red light. The light pulse which initiated the accumulation of radiolabeled chlorophyll a-apoproteins also induced the rapid conversion of protochlorophyllide to chlorophyll a. A chlorophyll-deficient mutant, xan-f(10), which is blocked in chlorophyll biosynthesis prior to protochlorophyllide formation, failed to accumulate radiolabeled chlorophyll a-apoproteins in the light even though transcripts for these apoproteins were present. A second mutant, xan-j(64), which accumulates chlorophyllide in the light but only low levels of chlorophyll a, also showed reduced accumulation of radiolabeled chlorophyll a-apoproteins upon illumination. These results suggest that the light-induced conversion of protochlorophyllide to chlorophyll a is necessary for accumulation of the plastid-encoded chlorophyll a-apoproteins and one red light photoreceptor controlling this response is the protochlorophyllide holochrome.

published proceedings

  • Plant Physiol

altmetric score

  • 3

author list (cited authors)

  • Klein, R. R., Gamble, P. E., & Mullet, J. E.

citation count

  • 55

complete list of authors

  • Klein, RR||Gamble, PE||Mullet, JE

publication date

  • December 1988