A frameshift mutation of the chloroplast mat K coding region is associated with chlorophyll deficiency in the Cryptomeria japonica virescent mutant Wogon-Sugi

Wogon-Sugi has been reported as a cytoplasmically inherited virescent mutant selected from a horticultural variety of Cryptomeria japonica. Although previous studies of plastid structure and inheritance indicated that at least some mutations are encoded by the chloroplast genome, the causative gene responsible for the primary chlorophyll deficiency in Wogon-Sugi, has not been identified. In this study, we identified this gene by genomic sequencing of chloroplast DNA and genetic analysis. Chloroplast DNA sequencing of 16 wild-type and 16 Wogon-Sugi plants showed a 19-bp insertional sequence in the mat K coding region in the Wogon-Sugi. This insertion disrupted the mat K reading frame. Although an indel mutation in the ycf 1 and ycf 2 coding region was detected in Wogon-Sugi, sequence variations similar to that of wogon-Sugi were also detected in several wild-type lines, and they maintained the reading frame. Genetic analysis of the 19 bp insertional mutation in the mat K coding region showed that it was found only in the chlorophyll-deficient sector of 125 full-sibling seedlings. Therefore, the 19-bp insertion in the mat K coding region is the most likely candidate at present for a mutation underlying the Wogon-Sugi phenotype.