Effects of temperature on the pattern of anthocyanin accumulation in seedlings of Polygonum cuspidatum

The site of the accumulation of anthocyanin was dependent on the temperatur e during irradiation in Polygonum cuspidatum seedling. Anthocyanin accumula ted first in the lower part of hypocotyls and then the site of accumulation gradually extended toward the upper part of hypocotyls when seedlings were irradiated with white light (WL) at 25 C. Etiolated seedlings accumulated anthocyanin only in the upper parts (hook and cotyledons) when the seedling s were irradiated with Wt at 5 C. De-etiolated seedlings that had been pre- irradiated with Wt for 1 day at 25 C accumulated anthocyanin both in upper and lower parts of the seedlings when the seedlings were irradiated with Wt at 5 C. Spectral sensitivity was dependent on the temperature during irrad iation. Red light (R), blue light (B), and near ultra-violet light (NUV) in duced the accumulation of anthocyanin at 5 C but only NUV was effective in inducing the accumulation of anthocyanin at 25 C. Dichlorophenyl dimethylur ea (DCMU) inhibited Wt-induced anthocyanin accumulation but did not NUV-ind uced anthocyanin accumulation at 25 C. However, sucrose promoted NUV action at 25 C, indicating that photosynthesis can promote NUV-induced anthocyani n accumulation. Distribution of phytochrome in etiolated seedlings, that wa s examined by spectrophotometry, was similar to the distribution of anthocy anin at 5 C. Furthermore, phytochrome remained after 48 hr irradiation with Wt at 5 C although phytochrome was rapidly degraded at 25 C.