Unique variegation characteristics of camellia cultivar 'Kumagai', in which chloroplasts disappear only in palisade tissue.

Previous studies reported that some types of variegation are caused by reduction of chlorophyll and infection of pathogens, and the variegated leaves showed lower photosynthetic capacity. To elucidate the mechanisms that control the variegation, we observed a variegated individual of camellia cultivar 'Kumagai' in which leaves are variegated only on the adaxial side. We found for the first time in seed plants that the amount of chloroplasts was decreased only in palisade tissue while healthy chloroplasts were maintained in spongy tissue. Variegated parts of leaves of variegated plant of 'Kumagai' maintained high Fv/Fm value in spite of lacking chloroplasts in palisade tissue. It should be also noted that highly variegated leaves were concentrated on specific branches. We also confirmed that this variegated 'Kumagai' was infected by Camellia japonica-associated betaflexivirus (CJaBV), camellia ringspot associated virus (CRSaV) and camellia yellow ringspot virus (CaYRV). These unique characteristics of variegation in 'Kumagai' will provide good opportunities to study the physiological and molecular mechanisms of variegation in future research.