Abstract
The comparative analysis of complete chloroplast and mitochondrial DNA sequences of the original inbred line 3629 and three extra nuclear mutant lines variegated-1, variegated-15, variegated-17, obtained by the N-nitroso-N-methylurea induced mutagenesis, was done. The studied mutant lines were presented two different phenotypes with diverse chlorophyll content: Pale/green mutant line variegated-17 with 1.8% relative (to 3629 line) chlorophyll content in mutant leaf tissue and yellow/green lines variegated-1, variegated-15 with 6.3% and 4.3% relative chlorophyll content, respectively. Each line had unique variation sites in chloroplast DNA. Among chloroplast SNP there were determined 7 nonsynonymous substitutions, which were located in psaA (variegated-1), petD, rpl36, ccsA (variegated-15), rps4, rpoA, rpoC1 (variegated-17). The SNP of variegated-17 line has resulted in the frameshift (rpoC1) and premature stop codon formations (rpoA, rpoC1). The whole genome sequencing of mitochondrial DNA mutant lines revealed no differences as compared with original line 3629. Summarizing current data and our previous research of variegated mutants we assume that pale/green variegated phenotype is associated with significant disturbance of RNA polymerase subunits genes, and the lesions in photosynthetic genes lead to yellow/green mutant phenotype.
Highlights
Chloroplast mutants are a convenient model for studying the mechanisms of chloroplast biogenesis and photosynthetic apparatus functioning (Greiner, 2012)
The variegated mutants with extra nuclear genetic origin are of particular interest because the plastid or mitochondrial DNA mutations could not directly effect on chlorophyll biosynthesis and the reduction of pigments occurs by the involvement of retrograde signaling pathways (Makarenko et al, 2016a)
Using Whole Genome Sequencing (WGS) sequencing, we have investigated the variability of chloroplast DNA in extra nuclear chlorophyll mutants of sunflower with various types of chlorophyll deficiency (Markin et al, 2016)
Summary
Chloroplast mutants are a convenient model for studying the mechanisms of chloroplast biogenesis and photosynthetic apparatus functioning (Greiner, 2012). Plants with mosaic mutant phenotype, such as variegated, are more excellent models for research the function of the gene product by studying its mode of action in both tissue types – normal and mutant (Yu et al, 2007). The variegated mutants with extra nuclear genetic origin are of particular interest because the plastid or mitochondrial DNA mutations could not directly effect on chlorophyll biosynthesis and the reduction of pigments occurs by the involvement of retrograde signaling pathways (Makarenko et al, 2016a). The variegated mutants with extra nuclear genetic origin are the appropriate models for investigating such fundamental problems in biology as nuclearcytoplasmic relationships. The Whole Genome Sequencing (WGS) of chloroplast and mitochondrial DNA makes it possible the accurate identification of
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