Down-regulation of specific plastid ribosomal proteins suppresses thf1 leaf variegation, implying a role of THF1 in plastid gene expression

Ma, Zhaoxue; Wu, Wenjuan; Huang, Weihua; Huang, Jirong

doi:10.1007/s11120-015-0101-5

Cited by 22 publications

(23 citation statements)

References 36 publications

(62 reference statements)

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“…SIG6 is a plastid transcription factor specifically controlling gene expression through the plastid-encoded RNA polymerase and the mutation of SIG6 suppresses thf1 variegation (Hu et al 2015). Genetic screening for the second-site suppressor lines of thf1 and var2 suggested that the reduced rate of plastid protein biosynthesis is important for chloroplast development in variegated leaves (Ma et al 2015b).…”

Section: Electronic Supplementary Materialsmentioning

confidence: 99%

Disruption of carotene biosynthesis leads to abnormal plastids and variegated leaves in Brassica napus

Zhao

Yan

et al. 2020

Mol Genet Genomics

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Leaf color is an important characteristic of normal chloroplast development. Variegated plants have green-and white-sectored leaves, which can be used to identify important pathways and molecular mechanisms of chloroplast development. We studied two Brassica napus variegation mutants from same one variegated ancestor, designated ZY-4 and ZY-8, which have different degrees of variegation. When grown in identical conditions, the ratio of white sectors in ZY-4 leaves is higher than in ZY-8. In both mutants, the cells in green sectors contain normal chloroplasts; while, the cells in white sectors contain abnormal plastids. Seedling chloroplasts ultrastructure of both mutants showed that the biogenesis of chloroplasts was blocked in early stages; delayed development and structual damage in ZY-4 were more serious than in ZY-8. Employing bulked segregant analysis(BSA), two bulks (BY142 and BY137) from BC 2 F 1 lines derived from ZY-4 and ZS11, and one bulk (BY56) from BC 2 F 1 lines derived from ZY-8 and ZS11, and screening by Brassica 60K SNP BeadChip Array, showed the candidate regions localized in chromosome A08 (BY142), C04 (BY137), and A08 (BY56), respectively. Transcriptome analysis of five seedling development stages of ZY-4, ZY-8, and ZS11 showed that photosynthesis, energy metabolism-related pathways and translation-related pathways were important for chloroplast biogenesis. The number of down-or up-regulated genes related to immune system process in ZY-4 was more than in ZY-8. The retrograde signaling pathway was mis-regulated in both mutants. DEG analysis indicated that both mutants showed photooxidative damages. By coupling transcriptome and BSA CHIP analyses, some candidate genes were identified. The gene expression pattern of carotene biosynthesis pathway was disrupted in both mutants. However, histochemical analysis of ROS revealed that there was no excessive accumulation of ROS in ZY-4 and ZY-8. Taken together, our data indicate that the disruption of carotene biosynthetic pathways leads to the variegation phenotypes of ZY-4 and ZY-8 and there are some functions that can compensate for the disruption of carotene biosynthesis in ZY-4 and ZY-8 to reduce ROS and prevent seedling mortality.

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Section: Electronic Supplementary Materialsmentioning

confidence: 99%

Disruption of carotene biosynthesis leads to abnormal plastids and variegated leaves in Brassica napus

Zhao

Yan

et al. 2020

Mol Genet Genomics

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“…2), are detected in the green but not the white leaf areas, specifically in the chloroplasts, of the var2 mutant grown even under normal light conditions, indicative of its persistent photooxidative stress (Kato et al, 2009). A series of genetic studies in Arabidopsis identified trans-acting factors suppressing var1/var2 leaf variegation; these included Clp subunits, translation factors, a pentatricopeptide repeat protein, a pseudouridine synthase homolog, a plastid transcriptionally active chromosome component, a prokaryotic-like peptide deformylase, ribosomal proteins, circularly permuted GTPase family proteins, and a sigma factor Miura et al, 2007;Yu et al, 2008Yu et al, , 2011Liu et al, 2010aLiu et al, , 2010bLiu et al, , 2013Adam et al, 2011;Wu et al, 2013;Powikrowska et al, 2014;Hu et al, 2015;Ma et al, 2015;Qi et al, 2016). Several models have been proposed to explain leaf variegation suppression, but the precise mechanism remains elusive (Miura et al, 2007;Yu et al, 2008).…”

Section: Ftshmentioning

confidence: 99%

Chloroplast Proteases: Updates on Proteolysis within and across Suborganellar Compartments

2016

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ORCID IDs: 0000-0003-1718-9121 (Y.K.); 0000-0001-9747-5042 (W.S.).Chloroplasts originated from the endosymbiosis of ancestral cyanobacteria and maintain transcription and translation machineries for around 100 proteins. Most endosymbiont genes, however, have been transferred to the host nucleus, and the majority of the chloroplast proteome is composed of nucleus-encoded proteins that are biosynthesized in the cytosol and then imported into chloroplasts. How chloroplasts and the nucleus communicate to control the plastid proteome remains an important question. Protein-degrading machineries play key roles in chloroplast proteome biogenesis, remodeling, and maintenance. Research in the past few decades has revealed more than 20 chloroplast proteases, which are localized to specific suborganellar locations. In particular, two energy-dependent processive proteases of bacterial origin, Clp and FtsH, are central to protein homeostasis. Processing endopeptidases such as stromal processing peptidase and thylakoidal processing peptidase are involved in the maturation of precursor proteins imported into chloroplasts by cleaving off the amino-terminal transit peptides. Presequence peptidases and organellar oligopeptidase subsequently degrade the cleaved targeting peptides. Recent findings have indicated that not only intraplastidic but also extraplastidic processive protein-degrading systems participate in the regulation and quality control of protein translocation across the envelopes. In this review, we summarize current knowledge of the major chloroplast proteases in terms of type, suborganellar localization, and diversification. We present details of these degradation processes as case studies according to suborganellar compartment (envelope, stroma, and thylakoids). Key questions and future directions in this field are discussed.Over 1 billion years of plastid evolution since the endosymbiosis of ancestral cyanobacteria (Douzery et al., 2004), chloroplast biogenesis has gained complexity, with large sets of the endosymbiont genes being transferred to host nuclear genomes. While only 100 endosymbiont genes remain in the plastid genome, with the corresponding proteins biosynthesized there, the nuclear genes have often gained complexity by duplication and diversification of the original endosymbiotic genes. This complexity raises numerous questions regarding (1) at what level gene expression is coordinately controlled, (2) what molecules coordinate the cross talk between chloroplasts and the nucleus, (3) how proteins get across membranes and become imported into chloroplasts, and (4) how the stoichiometries of nucleus-and chloroplast-encoded subunits within individual chloroplast protein complexes such as photosystems and Rubisco are strictly maintained.Given these questions, chloroplast biogenesis has remained a central subject in plant physiology for the last few decades (Jarvis and López-Juez, 2013). In our view, the aforementioned questions point to the importance of protein homeostasis and posttranslational modificat...

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“…THF1 has been suggested to be a subunit of PSII and also involved in the plasma membrane G-protein-mediated sugar signaling (Keren et al, 2005;Huang et al, 2006). Interestingly, var2 and thf1 share many similar genetic suppressor loci, including genes for chloroplast Clp protease complexes and chloroplast ribosomal proteins, suggesting a functional relationship between these two proteins (Yu et al, 2008;Liu et al, 2013;Wu et al, 2013;Ma et al, 2015).…”

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confidence: 99%

Balance between Cytosolic and Chloroplast Translation Affects Leaf Variegation

et al. 2017

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The development of functional chloroplasts relies on the fine coordination of expressions of both nuclear and chloroplast genomes. We have been using the Arabidopsis () () leaf variegation mutant as a tool to dissect the regulation of chloroplast development. In this work, we screened for genetic enhancer modifiers termed () mutants and report the characterization of the first locus, We showed that encodes the cytosolic 80S ribosome 40S small subunit protein RPS21B and the loss of causes the enhancement of leaf variegation. We further demonstrated that combined S21 activities from EVR1 and its close homolog, EVR1L1, are essential for Arabidopsis, and they act redundantly in regulating leaf development and leaf variegation. Moreover, using additional cytosolic ribosomal protein mutants, we showed that although mutations in cytosolic ribosomal proteins all enhance leaf variegation to varying degrees, the 40S subunit appears to have a more profound role over the 60S subunit in regulating VAR2-mediated chloroplast development. Comprehensive genetic analyses with suppressors that are defective in chloroplast translation established that the enhancement of leaf variegation by cytosolic ribosomal protein mutants is dependent on chloroplast translation. Based on our data, we propose a model that incorporates the suppression and enhancement of leaf variegation, and hypothesize that VAR2/AtFtsH2 may be intimately involved in the balancing of cytosolic and chloroplast translation programs during chloroplast biogenesis.

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Down-regulation of specific plastid ribosomal proteins suppresses thf1 leaf variegation, implying a role of THF1 in plastid gene expression

Cited by 22 publications

References 36 publications

Disruption of carotene biosynthesis leads to abnormal plastids and variegated leaves in Brassica napus

Disruption of carotene biosynthesis leads to abnormal plastids and variegated leaves in Brassica napus

Chloroplast Proteases: Updates on Proteolysis within and across Suborganellar Compartments

Balance between Cytosolic and Chloroplast Translation Affects Leaf Variegation

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