Fluorescence and Photochemical Investigations of Phytochrome in Higher Plants

Table 1

Characterisitcs of the two phenomenological phytochrome types, 𝑃𝑟^′ and 𝑃𝑟^′′, in etiolated dicotyledonous and monocotyledonous plants representing two native phyA types, phy𝐴^′ and phy𝐴^′′, respectively.

Parameter	Phy type
	Pr^′ = phyA^′	Pr^′′ = phyA^′′ (+phyB)^∗
Position of spectra, 𝜆max	Longer-wavelength (685/672 nm)	Shorter-wavelength (680/667 nm)
Half-band width, Δ𝜆	22–24 nm	30 nm
Pr→lumi-R conversion, 85 K, 𝛾1	0.49±0.03	≤0.05
Activation energy, 𝐸a	≤1 kJ mol^−1	≥10 kJ mol^−1
Pr→Pfr conversion, ≥273 K, 𝛾2	0.80–0.85	0.75
Content in tissues	Major, variable	Minor, conserved, saturable
Light lability	Light-labile	Relatively light-stable

∗phyB also belongs to the Pr^′′ type.