Abstract
Chloroplast biogenesis is one of the most important subjects in plant biology. In this study, an Arabidopsis early chloroplast biogenesis mutant with a delayed pale-greening phenotype (dpg1) was isolated from a T-DNA insertion mutant collection. Both cotyledons and true leaves of dpg1 mutants were initially albino but gradually became pale green as the plant matured. Transmission electron microscopic observations revealed that the mutant displayed a delayed proplastid-to-chloroplast transition. Sequence and transcription analyses showed that AtDPG1 encodes a putatively chloroplast-localized protein containing three predicted transmembrane helices and that its expression depends on both light and developmental status. GUS staining for AtDPG1::GUS transgenic lines showed that this gene was widely expressed throughout the plant and that higher expression levels were predominantly found in green tissues during the early stages of Arabidopsis seedling development. Furthermore, quantitative real-time RT-PCR analyses revealed that a number of chloroplast- and nuclear-encoded genes involved in chlorophyll biosynthesis, photosynthesis and chloroplast development were substantially down-regulated in the dpg1 mutant. These data indicate that AtDPG1 plays an essential role in early chloroplast biogenesis, and its absence triggers chloroplast-to-nucleus retrograde signalling, which ultimately down-regulates the expression of nuclear genes encoding chloroplast-localized proteins.
Highlights
The chloroplast is an essential organelle in plant cells and plays important roles in primary metabolism, such as CO2 fixation, manufacture of carbon skeletons and fatty acids, and synthesis of amino acids from inorganic nitrogen[1]
Because the majority of the several thousands of chloroplast proteins are encoded by the nucleus, it is not surprising that numerous mutants that are disrupted in chloroplast biogenesis have mutations on nuclear-encoded genes with diverse biological functions, including biosynthesis of photosynthetic pigments, thylakoid biogenesis, lipid
Our results indicate that AtDPG1 plays an essential role in early chloroplast biogenesis, its absence triggers chloroplast-to-nucleus retrograde signalling, down-regulating the expression of the nuclear genes encoding chloroplast-localized proteins
Summary
The chloroplast is an essential organelle in plant cells and plays important roles in primary metabolism, such as CO2 fixation, manufacture of carbon skeletons and fatty acids, and synthesis of amino acids from inorganic nitrogen[1]. Light is an important environmental cue triggering chloroplast biogenesis, a complex process in which photosynthetic pigments biosynthesis, the import of nuclear-encoded proteins, and the building of thylakoid networks embedded with photosynthetic electron transport complexes are integrated to establish fully functional chloroplasts[7,8]. The disruption of the functional and developmental state of the chloroplast by endogenous factors or exogenous environmental cues generates a wide variety of chloroplast retrograde signals that regulate the expression of many nuclear genes encoding chloroplast-localized proteins
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
