Photomorphogenic effects of UV-B radiation on hypocotyl elongation in wild type and stable-phytochrome-deficient mutant seedlings of cucumber

摘要: Hypocotyl elongation responses to ultraviolet-B (UV-B) radiation were investigated in glasshouse studies of de-etiolated seedlings a long-hypocotyl mutant (lh) cucumber (Cucumis sativus L.) deficient stable phytochrome, its near isogenic wild type (WT), and commercial hybrid (cv. Burpless). A single 6- or 8-h exposure UV-B applied against background white light inhibited hypocotyl rate by ca 50% lh WT seedlings. This effect was not accompanied reduction cotyledon area expansion dry matter accumulation. Plants recovered rapidly from inhibition it possible stimulate plants exposed application gibberellic acid. In all genotypes mainly consequence perceived the cotyledons; covering apex with filter that excluded failed prevent inhibition. These results indicate reduced does result assimilate limitation direct damage apical meristem elongating cells, strongly suggest is true photomorphogenic response UV-B. The fact fluences used very low relation total visible light, similarity wild-type plants, are consistent hypothesis acts through specific photoreceptor. It argued that, given weak correlation between visible-light levels most natural conditions, receptor may play an important sensory function providing information plant cannot be derived signals phytochrome blue/UV-A sensors.