A blue-light photoreceptor mediates the fluence-rate-dependent expression of genes encoding the small subunit of ribulose 1,5-bisphosphate carboxylase/oxygenase in light-grown Phaseolus vulgaris primary leaves

Abstract

The level of transcripts of genes encoding the small subunit of ribulose 1,5-bisphosphate carboxylase/ oxygenase (rbcS genes) in the primary leaves of Phaseolus vulgaris L. increases substantially when plants grown in a low fluence rate of white light (15 ~tmol m 2 s-~; 400-700 nm) are transferred to a tenfold higher fluence rate of identical spectral quality. To investigate which photoreceptor acts as the fluence-rate detector, plants grown for 16 d in low white light were transferred to blue-enriched or red light environments of various fluence rates. The results indicate that the fluence-rate-dependent increase in rbcS expression is mediated specifically by blue light. Red light of the same fluence rate, which was found to be equally effective in driving photosynthesis, had much less effect on expression, indicating that light absorbed by the photosynthetic pigments does not mediate the response. Moreover, there is no correlation of the transcript levels with either the cycling rate or photoequilibrium of the phytochrome system. Run-on assays with isolated nuclei indicate that blue light substantially increases the rate of rbcS transcription. Experiments with gene-specific probes show that individual members of the P. vulgaris rbcS gene family exhibit the fluence-rate-dependent, bluelight-mediated increase in expression. Abbreviations: rbcS = genes encoding the small subunit of ribulose 1,5-bisphosphate carboxylase/oxygenase; cab=genes encoding the major light-harvesting chlorophyll-protein of the LHCII complex; Pr, Pfr = the forms of phytochrome absorbing maximally red and far-red light, respectively; ~c=the calculated proportion of phytochrome in the Pfr form Correspondence to: G.I. Jenkins; FAX: 44(41)3304620

Effects of Light Quality on Growth of Crop Plants under Artificial Lighting

“…Sawbridge et al (1994) and Lopez-Juez and Hughes (1995) showed that an increase in blue light enhanced transcription levels of the gene of rbcS, Rubisco, and cytochrome f proteins. The opening of stomata is promoted more strongly by blue than by red light.…”

“…In general, chlorophyll content increases while the ratio of photosystem II to photosystem I (PSII/PSI) decreases under increased R : FR conditions, indicating an involvement of the phytochrome system. However, the light intensity dependent increase in transcription level of the gene of small subunit of Rubisco (rbcS), another element of photosynthetic acclimation, was mediated specifically by blue light (Sawbridge et al, 1994). Lopez-Juez and Hughes (1995) showed that the chlorophyll a/b ratio, Rubisco, and cytochrome f proteins of pea seedlings (Pisum sativum L.) increased in response to an increase in blue light and suggested that a blue light photoreceptor controlled the light acclimation responses.…”

“…Merr.] : Warrington et al, 1976aWarrington et al, , 1976bCathey and Campbell, 1977;Britz and Sager, 1990;Wheeler et al, 1991 ;Britz and Cavins, 1993;Dougher and Bugbee, 2001a;kidney bean [Phaseolus vulgaris L.] : Barreiro et al, 1992;Maas et al, 1995;Hanyu et al, 1996;Hanyu andShoji, 2000a, 2000b; peanut [Arachis hypogaea L.] : Montley et al, 2001), andvegetables (lettuce : Cathey andCampbell, 1979;Krizek and Ormrod, 1980;Tibbitts et al, 1983;Knight andMitchell, 1988a, 1988b;Koontz et al, 1987;Mortensen and StrOmme, 1987;Inada and Yabumoto, 1989;Murakami et al, 1992;Eskins et al, 1997;Tomita et al, 1998;Dougher andBugbee, 2001 a, 2001 b ;spinach : Tibbitts et al, 1983;Hanyu and Shoji, 2002 , 1983). LEDs emitting a variety of defined wavelengths are available now, and became more common recently as a light source in plant growth studies.…”

Red/far-red and blue light-responsive regions of maize rbcS-m3 are active in bundle sheath and mesophyll cells, respectively.

“…Other photomorphogenic systems are driven through UVA/blue light-and UVB-absorbing photoreceptors (10). In several species the increase in expression of rbcS upon illumination of dark-grown seedlings has been shown to be mediated by a phytochrome system (11)(12)(13)(14)(15)(16) (20). In none of these cases is it known whether signals cross over between postphotoperception signal transduction chains.…”

Ontogenetic regulation and photoregulation of members of the Phaseolus vulgaris L. rbcS gene family

“…Expression is also subject to temporal regulation during development (Nelson et al 1984;Greenland et al 1987;Wanner and Gruissem 1991). In most species, expression of the rbcS genes is stimulated by light mediated by phytochrome (reviewed by Tobin and Silverthorne 1985) or a blue-light photoreceptor Clugston et al 1991;Sawbridge et al 1994) depending on the stage of leaf development. In addition, expression is regulated by a range of other environmental and endogenous signals, including by metabolites such as sucrose and glucose (Sheen 1990;Krapp et al 1993).…”