The Arabidopsis chloroplast ribosome recycling factor is essential for embryogenesis and chloroplast biogenesis.
To gain insight into the functions of the nuclear-encoded factors involved in chloroplast development, we characterized the high chlorophyll fluorescence and pale green mutant 108-1 (designated as hfp108-1) of Arabidopsis thaliana. Map-based cloning revealed that the mutant contains a tandem repeat of part of the sequence (including 116 nucleotides from 631 to 746 bp downstream of the ATG) of At3g63190, which encodes a chloroplast ribosome recycling factor homologue and was named AtcpRRF. The chloroplasts of hfp108-1 plants contain few internal thylakoid membranes and are severely defective in the accumulation of chloroplast-encoded proteins. In vivo labeling experiments showed a drastic decrease in the synthesis of the chloroplast-encoded proteins, which may be attributed primarily to reduced translation of the corresponding mRNA molecules. The level of the HFP108 transcript was greatly reduced in hfp108-1, so hfp108-1 showed a weak phenotype, and null alleles of HFP108 (hfp108-2) were embryonic lethal. Observations with cleared seeds in the same silique showed that homozygous hfp108-2 seeds were blocked at the heart stage and did not develop further. Thus, these results suggest that AtcpRRF is essential for embryogenesis and chloroplast biogenesis.
Photosynthesis Research Center, Institute of Botany, Chinese Academy of Sciences, Beijing, China.
Liyuan
L
Wang
Min
M
Ouyang
Qiannan
Q
Li
Meijuan
M
Zou
Jinkui
J
Guo
Jinfang
J
Ma
Congming
C
Lu
Lixin
L
Zhang
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000196:embryology* / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D003001:Cloning, Molecular; D018744:DNA, Plant / Q000235:genetics; D017343:Genes, Plant; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D009154:Mutation; D030821:Plants, Genetically Modified; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism*; D012270:Ribosomes / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D020080:Tandem Repeat Sequences
D029681:Arabidopsis Proteins; D018744:DNA, Plant; D012269:Ribosomal Proteins; C087267:ribosome releasing factor