Induction of plant gene expression by light

116

Section: Methodsmentioning

confidence: 99%

Expression of Light-Harvesting Chlorophyll a/b-Protein Genes Is Phytochrome-Regulated in Etiolated Arabidopsis thaliana Seedlings

Karlin-Neumann

Sun²,

Tobin³

1988

116

“…One must view these conclusions with a certain amount of caution, since, as discussed by several authors (22,23) one cannot be completely certain that transcriptional activity by isolated nuclei is a true reflection of their transcriptional activity in vivo. In the present system, the situation is exacerbated by the need to macerate the tissue for 2.5 h. As shown elsewhere (7), however, the 0.7 M mannitol solution used in the maceration treatment strongly inhibits the greening response, and it seems reasonable that normal regulatory responses are probably suspended during maceration, as was the case with tobacco protoplasts (9,10,24 …”

Section: Resultsmentioning

confidence: 99%

Phytochrome Regulation of Greening in Barley

Mösinger

Batschauer²,

Apel³

et al. 1988

This paper presents further information on the photobiology of light-induced changes both in mRNA abundance and transcriptional activity in barley seedlings. Our hope is that such studies, together with those in our recent paper on greening (7), will provide quantitative information of use in determining at what level or levels phytochrome might be controlling steps in chloroplast development, and the extent to which any such control might limit the greening process per se. Batschauer and Apel (3) recently presented data on the positive regulation of mRNA abundance for LHCP in barley and the negative regulation of mRNA abundance for Pchl-reductase by Pfr. In addition, Mosinger et al. (17,18) studied positive phytochrome regulation of transcription of the LHCP mRNA in in vitro run-on transcription experiments with isolated nuclei, and also negative regulation of transcription of the Pchl-reductase gene. Hence, these two mRNAs were ideal for investigating fluence-response relationships both at the level of mRNA abundance at different times following irradiation and at the transcriptional level. It was our hope that by extending our photobiological knowledge of these systems, we might understand a few more of the complexities underlying phytochrome regulation of chloroplast development. These results have been discussed briefly elsewhere (6). MATERIALS AND METHODSPlant Material. Dry seeds of barley were planted on moist vermiculite and grown for 6 d as described previously (7). For the present experiments, roughly 150 seeds were planted per small plastic box (5 x 5 x 10 cm) instead of about 75, as was done for the Chl studies (7). Save for specific light treatments, as mentioned below, plants were at all times kept in complete darkness. At the end of 6 d of growth, the seedlings were between 10 and 14 cm tall.For mRNA abundance measurements, leaves were harvested in dim green light by cutting just above the coleoptile tips, yielding pieces 5 to 9 cm in length. (By contrast, Mosinger et al. [17,18]

“…The transition from such etioplasts to photosynthetically competent chloroplasts involves the synthesis of Chl and many chloroplast polypeptides, and the reorganization of plastid structure, directed by the nuclear and plastid genetic compartments (9,13,18,19,(27)(28)(29). Light regulates several aspects of this greening process.…”

mentioning

confidence: 99%

“…Light regulates several aspects of this greening process. In particular, continuous light is required for photoreduction of Pchlide, and a pulse of light acts through phytochrome to increase the levels of nuclear mRNAs encoding chloroplast proteins (1,9,16,18,20,21,23,24,29,30). Blue light receptors have also been implicated in the control of plastid (5) and nuclear-encoded mRNAs (20,30).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Photocontrol of the Accumulation of Plastid Polypeptides during Greening of Tomato Cotyledons

Pauncz¹,

Gepstein²,

Horwitz³

1992

A pulse of red light acting through phytochrome accelerates the formation of chlorophyll upon subsequent transfer of dark-grown seedlings to continuous white light. Specific antibodies were used to follow the accumulation of representative subunits of the major photosynthetic complexes during greening of seedlings of tomato (Lycopersicon esculentum). The time course for accumulation of the various subunits was compared in seedlings that received a red light pulse 4 h prior to transfer to continuous white light and parallel controls that did not receive a red light pulse. The lightharvesting chlorophyll-binding proteins of photosystem 11 (LHC II), the 33-kD extrinsic polypeptide of the oxygen-evolving complex (OEC1), and subunit 11 of photosystem I (psaD gene product) all increased in the light, and did so much faster in seedlings that received the inductive red light pulse. The red light pulse had no significant effect on the abundance of the small subunit of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco), nor on several plastid-encoded polypeptides: the large subunit of Rubisco, the ,B subunit of the CF1 complex of plastid ATPase, and the 43-and 47-kD subunits of photosystem 11 (CP43, CP47). Subunits I (cytochrome b6f) and IlIl (Rieske Fe-S protein) of the cytochrome b6f complex showed a small or no increase as a result of the red pulse. The potentiation of greening by a pulse of red light, therefore, is not expressed uniformly in the abundance of all the photosynthetic complexes and their subunits.