Fluorescence and photochemical properties of phytochromes in wild‐type wheat and a transgenic line overexpressing an oat phytochrome A (PHYA) gene: functional implications

Abstract

Etiolated seedlings of wild-type wheat and a transgenic line overexpressing an oat PHYA gene were investigated by the use of in situ low-temperature fluorescence spectroscopy. The red-absorbing phytochrome form, Pr, was characterized by (1) fluorescence emission spectrum; (2) total phytochrome content, and (3) by the extent of the Pr → → → → lumi-R photoconversion at low temperature ( γ γ γ γ 1 ), and of the Pr → → → → Pfr photoconversion at ambient temperature ( γ γ γ γ 2 ) as derived from emission data. All the characteristics were shown to be variable and to depend on (1) organ and tissue used; (2) seedling age; (3) transgenic wheat modification, and (

Two Native Pools of Phytochrome A in Monocots: Evidence from Fluorescence Investigations of Phytochrome Mutants of Rice

“…Because the properties and relative content of the two phyA species in rice (WT seedlings and the phyB mutant) are very close to those of the two phenomenological phy pools (Pr′ and Pr′) in the WT monocots ( i.e. oat, wheat, barley and maize) (19–21), we believe it likely that the two phyA populations are present in all monocots.…”

“…We used low‐temperature fluorescence spectroscopy of phytochrome in etiolated tissues as a major experimental approach (16–21). The procedure of the rice seedlings growth, sample preparation and spectral measurements were essentially the same as those reported elsewhere (21).…”

“…The two Pr types were also found in monocots ( i.e. oat, wheat, barley, rice and maize (19–21)), which, similar to dicots, could be attributed to the presence of phyA′ and phyA″, on the basis of their spectroscopic and photochemical properties and their abundance in and distribution among plant species and tissues under different physiological conditions. However, the lack of phyA and phyB mutants of monocots did not allow us to present a rigorous proof that phyA in these plants also exists in the two isoforms.…”

Two modes of the light-induced phytochrome A decline – with and without changes in the proportion of its isoforms (phyA′ and phyA″): evidence from fluorescence investigations of mutant phyA-3D pea

“…The experimental approach was the same as that used earlier (see [11][12][13][14]17,18,21,22] and the literature cited therein). To obtain the phytochrome parameters in the sample, low-temperature (85 K) emission spectra (wavelength of the excitation, k e , 610 or 650 nm) were taken under two different experimental settings (see Figs.…”

“…It was found that the major and light-labile phyA 0 is primarily responsible for the HIR and possibly VLFR during de-etiolation. The more light-stable minor phyA 00 may be functional in light-grown plants and may also modify the action of phyA 0 inhibiting its activity [10,17,18]. However, the exact nature of the two phyA forms and functional distinctions between them still remain obscure.…”