Two separate photoreceptors control hypocotyl growth in green seedlings

摘要: PHOTOCONTROL of elongation growth has been extensively studied in dark-grown (etiolated) seedlings for some time. However, only relatively recently detailed attention given to green (de-etiolated) plants. One reason this is that the photoreceptor, phytochrome, can easily be detected spectrophotometrically non-green tissues but not tissue containing chlorophyll. There agreement photoreceptor operates its low-energy mode (low irradiances or fluence rates, with red/far-red reversibility) as well dark-grown, seedlings. In high-energy (high and time dependency), exemplified by action prolonged irradiation far-red, phytochrome might act etiolated seedlings1–3. Photoregulation stem extension de-etiolated also achieved blue light (400–500 nm), it still clear if a other than responsible effect. Kinetic studies on suggest operation separate blue-responsive photosystem2. Notwithstanding this, suggested blue-light control hypocotyl due solely absorption phytochrome4. This claim, together evidence changes photoequilibria exert profound effects upon extension, may lead one believe major controlling We report here, however, work strongly indicates two pigment systems seedlings—phytochrome blue-lightreceptor. Both produce same response—inhibition—but we have found possible their examining times at which response commences.