Fluorescence investigations of phytochrome (phy) in rice (Oryza sativa L. cv. Nipponbare) mutants deficient in phyA, phyB and phyA plus phyB were performed. Total content of the pigment (Ptot) and its spectroscopic and photochemical characteristics were determined in different parts of the dark–grown and far-red light (FR)–grown coleoptiles. Spectroscopically, phyA in the phyB mutant was identical to phyA in the wild-type (WT) and the extent of the conversion from Pr to lumi-R at 85 K was the same for phyA in both lines and varied similarly, depending on the part of the coleoptile used. The latter finding proved that phyA in rice is heterogeneous and comprises two phyA populations, phyA′ and phyA″. Functional properties of phyA were also determined. In the dark the phyB mutant had a higher content of phyA, inactive protochlorophyllide (Pchlide633) and active protochlorophyllide (Pchlide655) than WT and its coleoptile was longer, indicating that phyB may affect the development of WT seedlings in the dark. Constant FR drastically reduced the content of phyA, Pchlide633 and Pchlide655 and brought about coleoptile shortening and appearance of the first leaf, whereas pulsed FR of equal fluence was less effective. This suggested that the reactions were primarily of the high irradiance responses type, which are likely to be mediated by phyA′. The effects on protochlorophyllide biosynthesis and growth responses type were more pronounced in the phyB mutant than in the WT seedlings, which can be connected with the higher phyA′ content in the phyB mutant and/or phyB interference with its action in WT seedlings. In the phyA mutant induction of Pchlide633 and Pchlide655 biosynthesis was observed under constant FR, indicating that phyC may be responsible for this effect.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 82 • No. 4