Arabidopsis CIA2 and CIL have distinct and overlapping functions in regulating chloroplast and flower development.

Arabidopsis CHLOROPLAST IMPORT APPARATUS 2 (CIA2) and its paralogous protein CIA2-LIKE (CIL) are nuclear transcription factors containing a C-terminal CCT motif. CIA2 promotes the expression of nuclear genes encoding chloroplast-localized translocons and ribosomal proteins, thereby increasing the efficiency of protein import and synthesis in chloroplasts. We have previously reported that CIA2 and CIL form a homodimer or heterodimer through their C-terminal sequences and interact with other nuclear proteins, such as CONSTANS (CO), via their N-terminal sequences, but the function of CIL had remained unclear.

Sequence analysis and protein interactions of Arabidopsis CIA2 and CIL proteins.

Background: A previous screening of Arabidopsis thaliana for mutants exhibiting dysfunctional chloroplast protein transport identified the chloroplast import apparatus (cia) gene. The cia2 mutant has a pale green phenotype and reduced rate of protein import into chloroplasts, but leaf shape and size are similar to wild-type plants of the same developmental stage. Microarray analysis showed that nuclear CIA2 protein enhances expression of the Toc75, Toc33, CPN10 and cpRPs genes, thereby up-regulating protein import and synthesis efficiency in chloroplasts.

Transcriptome profile of cup-shaped galls in Litsea acuminata leaves.

Background: Insect galls are atypical plant tissues induced by the invasion of insects. Compared to the host leaf, gall tissues lose photosynthetic ability, but have higher soluble sugar content. Although the physiological and biochemical regulation of gall tissues have been demonstrated, the mechanism of genetic regulation has only been analyzed in few studies.

Postglacial range expansion and the role of ecological factors in driving adaptive evolution of Musa basjoo var. formosana.

Genetic variation evolves during postglacial range expansion of a species and is important for adapting to varied environmental conditions. It is crucial for the future survival of a species. We investigate the nuclear DNA sequence variation to provide evidence of postglacial range expansion of Musa basjoo var.

Characterization of differential expression and leader intron function of Arabidopsis atTOC159 homologous genes by transgenic plants.

Background: Accurate import of thousands of nuclear-encoded proteins is an important step in plastid biogenesis. However, the import machinery of cytosolic precursor proteins to plastids relies on the Toc and Tic (translocons on the outer envelope and inner envelope membrane of chloroplasts) complexes. Toc159 protein was identified in pea (Pisum sativum) as a major receptor for the precursor proteins.

CIA2 coordinately up-regulates protein import and synthesis in leaf chloroplasts.

Plastid biogenesis and maintenance depend on the coordinated assembly of proteins imported from the cytosol with proteins translated within plastids. Chloroplasts in leaf cells have a greater need for protein import and protein synthesis than plastids in other organs due to the large amount of proteins required for photosynthesis. We previously reported that the Arabidopsis (Arabidopsis thaliana) transcription factor CIA2 specifically up-regulates leaf expression of genes encoding protein translocons Toc33 and Toc75, which are essential for protein import into chloroplasts.

Characterization of Arabidopsis glutamine phosphoribosyl pyrophosphate amidotransferase-deficient mutants.

Using a transgene-based screening, we previously isolated several Arabidopsis mutants defective in protein import into chloroplasts. Positional cloning of one of the loci, CIA1, revealed that CIA1 encodes Gln phosphoribosyl pyrophosphate amidotransferase 2 (ATase2), one of the three ATase isozymes responsible for the first committed step of de novo purine biosynthesis. The cia1 mutant had normal green cotyledons but small and albino/pale-green mosaic leaves.