Editing of accD and ndhF chloroplast transcripts is partially affected in the Arabidopsis vanilla cream1 mutant.
The vanilla cream1 (vac1) albino mutant is defective in a gene encoding a chloroplast-localized pentatricopeptide repeat protein of the DYW subgroup. However, the carboxyl-terminal DYW motif is truncated in VAC1. To identify vac1-specific phenotypes, we compared 34 chloroplast RNA editing sites and approximately 90 chloroplast gene expression patterns among wild type, vac1 and another albino mutant ispH, which is defective in the plastid isoprenoid biosynthesis pathway. We found that the editing of accD and ndhF transcripts is partially affected in vac1. In addition, steady-state levels of chloroplast rRNAs are significantly decreased in vac1. The expression of plastid-encoded RNA polymerase transcribed genes is down-regulated, whereas the expression of nucleus-encoded RNA polymerase transcribed genes is up-regulated in vac1. Although the development and function of mutant chloroplasts are severely impaired, steady-state mRNA levels of nucleus-encoded photosynthetic genes are not affected or are only slightly decreased in vac1. The ZAT10 gene encodes a transcription factor and its expression is down-regulated by norflurazon treatment in wild type. This norflurazon effect was not observed in vac1. These results suggest that the VAC1 protein may be involved in plastid-to-nucleus retrograde signaling in addition to its role in chloroplast RNA editing and gene expression. A defect in a key biosynthetic pathway can have many indirect effects on chloroplast gene expression as is seen in the ispH mutant. Similarly, the vac1 mutant has pleiotropic molecular phenotypes and most of which may be indirect effects.
Tseng
Ching-Chih
CC
Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan.
Sung
Tzu-Ying
TY
Li
Yi-Chiou
YC
Hsu
Shih-Jui
SJ
Lin
Chien-Li
CL
Hsieh
Ming-Hsiun
MH
D000103:Acetyl-CoA Carboxylase / Q000235:genetics*; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics*; D002734:Chlorophyll / Q000737:chemistry / Q000378:metabolism; D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D005453:Fluorescence; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D018613:Microscopy, Confocal; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D009154:Mutation; D009245:NADH Dehydrogenase / Q000235:genetics; D010641:Phenotype; D017393:RNA Editing; D018747:RNA, Chloroplast / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid
D029681:Arabidopsis Proteins; D018747:RNA, Chloroplast; D002734:Chlorophyll; D049452:Green Fluorescent Proteins; D009245:NADH Dehydrogenase; D000103:Acetyl-CoA Carboxylase