Mutations in a plastid-localized elongation factor G alter early stages of plastid development in Arabidopsis thaliana

Department of Biology, Indiana University, Bloomington, IN 47405, USA.
BMC Plant Biology (Impact Factor: 3.81). 02/2007; 7(1):37. DOI: 10.1186/1471-2229-7-37
Source: PubMed


Proper development of plastids in embryo and seedling tissues is critical for plant development. During germination, plastids develop to perform many critical functions that are necessary to establish the seedling for further growth. A growing body of work has demonstrated that components of the plastid transcription and translation machinery must be present and functional to establish the organelle upon germination.
We have identified Arabidopsis thaliana mutants in a gene that encodes a plastid-targeted elongation factor G (SCO1) that is essential for plastid development during embryogenesis since two T-DNA insertion mutations in the coding sequence (sco1-2 and sco1-3) result in an embryo-lethal phenotype. In addition, a point mutation allele (sco1-1) and an allele with a T-DNA insertion in the promoter (sco1-4) of SCO1 display conditional seedling-lethal phenotypes. Seedlings of these alleles exhibit cotyledon and hypocotyl albinism due to improper chloroplast development, and normally die shortly after germination. However, when germinated on media supplemented with sucrose, the mutant plants can produce photosynthetically-active green leaves from the apical meristem.
The developmental stage-specific phenotype of the conditional-lethal sco1 alleles reveals differences in chloroplast formation during seedling germination compared to chloroplast differentiation in cells derived from the shoot apical meristem. Our identification of embryo-lethal mutant alleles in the Arabidopsis elongation factor G indicates that SCO1 is essential for plant growth, consistent with its predicted role in chloroplast protein translation.

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    • "The involvement and general importance of photoreceptors in this process, including both phytochromes and cryptochromes, also has been described (Chun et al., 2001; Thum et al., 2001; Wellburn and Wellburn, 1973), and in some plant species, specific contributions of blue and red light have been quantified (eg. in Cucumis,Hogewoning et al., 2010). Development of plastids in both embryonic development and post-germination is still poorly understood, but involve many transcriptional and translation mechanisms, including plastidspecific elongation factor G (SCO1), required for embryonic survival and seedling plastid development and subsequent survival (Ruppel and Hangarter, 2007). A limited number of factors that function downstream of the photoreceptors have been identified. "
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