The chloroplast ribosomal protein L21 gene is essential for plastid development and embryogenesis in Arabidopsis

Abstract

Embryogenesis in higher plants is controlled by a complex gene network. Identification and characterization of genes essential for embryogenesis will provide insights into the early events in embryo development. In this study, a novel mutant with aborted seed development (asd) was identified in Arabidopsis. The asd mutant produced about 25% of albino seeds at the early stage of silique development. The segregation of normal and albino seeds was inherited as a single recessive embryo-lethal trait. The gene disrupted in the asd mutant was isolated through map-based cloning. The mutated gene contains a single base change (A to C) in the coding region of RPL21C (At1g35680) that is predicted to encode the chloroplast 50S ribosomal protein L21. Allele test with other two T-DNA insertion lines in RPL21C and a complementation test demonstrated that the mutation in RPL21C was responsible for the asd phenotype. RPL21C exhibits higher expression in leaves and flowers compared with expression levels in roots and developing seeds. The RPL21C-GFP fusion protein was localized in chloroplasts. Cytological observations showed that the asd embryo development was arrested at the globular stage. There were no plastids with normal thylakoids and as a result no normal chloroplasts formed in mutant cells, indicating an indispensable role of the ASD gene in chloroplasts biogenesis. Our studies suggest that the chloroplast ribosomal protein L21 gene is required for chloroplast development and embryogenesis in Arabidopsis.

The DEAD-box RNA Helicase RH50 Is a 23S-4.5S rRNA Maturation Factor that Functionally Overlaps with the Plastid Signaling Factor GUN1

“…3E). Growth arrest at the globular stage of embryo development has been reported for several other mutants deficient in plastid ribosomal proteins (like prps20, prpl1, prpl4, prpl21, prpl27, or prpl35; Romani et al, 2012;Yin et al, 2012). Taken together, these analyses suggest that the loss of RH50, like that of GUN1, generally tends to potentiate the effects of mutations in genes for plastid ribosomal subunits (such as prors1, prps1, prps21, prpl11, and prpl24).…”

Insights from the Cold Transcriptome and Metabolome of Dendrobium officinale: Global Reprogramming of Metabolic and Gene Regulation Networks during Cold Acclimation

“…Furthermore, genes involved in calcium and calmodulin signaling network were the core components of C2, C3, most of which are represented by CDPK gene families (IRE4, bam1, ERECTA, HSL1, At1g74360, and IKU2) and MAPK cascade (MKK9) (Supplementary Table S6 in Supplementary Material). Genes involved in chloroplast development play a critical role in adapting stress environments (Yin et al, 2012). Interestingly, the C4 cluster contained multiple marker genes associated with protein synthesis by maintaining the chloroplast membrane system, including chloroplast ribosome proteins (RPL3, RPL5, RPL23, RPL28C, and RPL4A), thylakoidal processing peptidase 1 (TPP1), elongation factor TU GTP-binding domain (Eftud1).…”

The Translational Apparatus of Plastids and Its Role in Plant Development

“…The function of the nucleus-encoded plastid ribosomal proteins has been studied mainly in the model plant Arabidopsis by using publicly available T-DNA insertion lines (Pesaresi et al, 2001; Morita-Yamamuro et al, 2004; Bryant et al, 2011; Tiller et al, 2012; Romani et al, 2012), mutants generated by RNAi approaches (Tiller et al, 2012), or mutants identified in EMS mutagenesis screens (Yin et al, 2012). Due to the lack of a chloroplast transformation system for Arabidopsis , the essentiality of plastid-encoded ribosomal proteins has been exclusively investigated in tobacco ( Nicotiana tabacum ).…”