ISSN:
1399-3054
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
In the present investigation, an attempt has been made to understand the mechanism of light signal transduction in regulation of steady-state transcript levels of the plastid genes psbA, psaA and rbcL in rice (Oryza sativa L. ssp. indica cv. Pusa 169) seedlings. Red light irradiation of 5-day-old etiolated seedlings for 5 min upregulates the transcript levels of the above-mentioned plastid genes, while far-red light exposure subsequent to red light reverses this effect, indicating the involvement of phytochrome(s). Ca2+ and the Ca2+ ionophore, A23187 increase the level of transcripts in the dark-grown seedlings. Ca2+ chelators (EGTA and BAPTA) as well as Ca2+ channel blockers (nifedipine and verapamil) suppress the accumulation of all transcripts in light. This suggests the involvement of Ca2+ in the photoregulation of plastid genes. Okadaic acid, a specific inhibitor of protein phosphatase 1 and 2A (PP1 and PP2A), and sodium fluoride (NaF), a general inhibitor of protein phosphatases, significantly prevent the light-induced increase in transcript levels of the plastid genes. Staurosporine, a protein kinase inhibitor, causes an increase in the transcript levels in darkness and a further enhancement in conjunction with light. The results suggest that light signal transduction downstream to phytochrome(s) involves Ca2+ and phosphorylation for controlling the pattern of plastid gene expression. Phosphorylation inhibits light-activated gene expression in chloroplasts.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1034/j.1399-3054.1999.105415.x
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