Characterization of a high chlorophyll fluorescence mutant of Arabidopsis thaliana

Abstract

To understand the regulatory mechanism of chloroplast gene expression in higher plant, we have screened hcf (high chlorophyll fluorescence) mutants of Arabidopsis thaliana using a chlorophyll fluorescence imaging system. Since chlorophyll fluorescence emitted from photosystem II reflects the state of photosynthetic electron flow, most of hcf mutants are defective in either component of photosynthetic complexes or the regulatory mechanism of chloroplast gene expression. Approximately 50,000 seeds mutagenized by ethyl methanesulfonate or T-DNA insertion were screened resulting in the isolation of 59 putative mutants. Among these mutants, 2627-2, one of hcf mutants generated by T-DNA insertion mutagenesis was further characterized because the kanamycin resistance carried by T-DNA and the hcf mutant phenotype was co-segregated, suggesting that the target gene was tagged with inserted T-DNA. This mutant was pale green and exhibiting reduced growth and low Fv/Fm. Southern blot analysis revealed T-DNA was inserted at a single site with at least two tandem copies. Our current attempt to isolate T-DNA-inserted genome sequence using thermal asymmetric interlaced (TAIL-) PCR and further characterization of mutation will be discussed.