The Pentratricopeptide Repeat Protein DELAYED GREENING1 Is Involved in the Regulation of Early Chloroplast Development and Chloroplast Gene Expression in Arabidopsis    

Abstract

An Arabidopsis (Arabidopsis thaliana) mutant that exhibited a delayed greening phenotype (dg1) was isolated from a population of activation-tagged Arabidopsis lines. Young, inner leaves of dg1 mutants were initially very pale, but gradually greened and mature outer leaves, more than 3 weeks old, appeared similar to those of wild-type plants. Sequence and transcription analyses showed that DG1 encodes a chloroplast protein consisting of eight pentratricopeptide repeat domains and that its expression depends on both light and developmental status. In addition, analysis of the transcript profiles of chloroplast genes revealed that plastid-encoded polymerase-dependent transcript levels were markedly reduced, while nucleus-encoded polymerasedependent transcript levels were increased, in dg1 mutants. Thus, DG1 is probably involved in the regulation of plastidencoded polymerase-dependent chloroplast gene expression during early stages of chloroplast development.

A Functional Component of the Transcriptionally Active Chromosome Complex, Arabidopsis pTAC14, Interacts with pTAC12/HEMERA and Regulates Plastid Gene Expression

“…6B). A similar transcriptional pattern was observed in the SIG6 knockout mutant Schweer et al, 2006) and other PEP-deficient mutants, such as ptac2/6/12 (Pfalz et al, 2006), clb19 (ChateignerBoutin et al, 2008, dg1 (Chi et al, 2008), and ys1 (Zhou et al, 2008). In addition, a 4.8-kb transcript was also detected for rbcL in ptac14-1 (Fig.…”

“…Recent reports have revealed that mutations in several of the genes encoding TAC components cause deficiencies in PEP-dependent transcription (Pfalz et al, 2006;Garcia et al, 2008;Myouga et al, 2008). As shown in Figure 5, real-time RT-PCR and northern-blot hybridization showed that the expression pattern of plastid genes in ptac14-1 mutants resembles that observed in Drpo mutants (Serino and Maliga, 1998;Krause et al, 2000) and in mutants with lesions in PEP function (Hess et al, 1993;Allison et al, 1996;Hajdukiewicz et al, 1997;Chateigner-Boutin et al, 2008;Chi et al, 2008). These results suggest that pTAC14 is indispensable for the proper function of the PEP transcription machinery.…”

Disruption of a Rice Pentatricopeptide Repeat Protein Causes a Seedling-Specific Albino Phenotype and Its Utilization to Enhance Seed Purity in Hybrid Rice Production

“…Fisk et al (1999) first reported a maize PPR gene, (for CHLOROPLAST RNA PROCESSING1), which was implicated by genetic analysis in processing and translation of plastid pet transcripts. Similar effects on plastid transcripts were subsequently observed in other mutants from Arabidopsis (Hashimoto et al, 2003;Meierhoff et al, 2003;Yamazaki et al, 2004;ChateignerBoutin et al, 2008ChateignerBoutin et al, , 2011Chi et al, 2008;Okuda et al, 2009Okuda et al, , 2010Yu et al, 2009;Johnson et al, 2010), rice (Kazama and Toriyama, 2003;Komori et al, 2004;Gothandam et al, 2005), and maize (Williams and Barkan, 2003;Schmitz-Linneweber et al, 2006;Pfalz et al, 2009;Prikryl et al, 2011). Additional evidence for a role of PPR proteins in regulating organelle gene expression has also come from positional cloning of several cytoplasmic male sterility (CMS) restorer genes from petunia (Petunia hybrida; Bentolila et al, 2002) and radish (Raphanus sativus; Brown et al, 2003;Desloire et al, 2003;Koizuka et al, 2003).…”

“…For example, the Arabidopsis dg1 (for delayed greening1) and ys1 mutants (for yellow seedling1) display a seedling-stage-specific albino and yellow seedling phenotype, respectively. Both DG1 and YS1 encode chloroplast-targeted PPR proteins and YS1 has been shown to be required for editing of rpoB transcripts (Chi et al, 2008;Zhou et al, 2009). The null mutation of the maize PPR2 gene leads to albino seedlings, but does not affect seed development or gametogenesis (Williams and Barkan, 2003).…”

“…The primer pair used for YSA was: 59-ggaccatggacatgccccgcgtttgcgccgcccctcg-39 and 59-catcactagtttgctcccctccacaagaacattgag-39. The vectors for the nuclear localization signal of the fibrillarin protein and the transit peptide of the small subunit of ribulose bisphosphate carboxylase of Arabidopsis (Arabidopsis thaliana) were kindly provided by Dr. W. Chi (Chi et al, 2008). The constructs were introduced into Arabidopsis protoplasts according to the protocols described previously (Yoo et al, 2007).…”