|Liu, Hong - PLANT BIO UOFI URB IL|
Submitted to: Plant Physiology Supplement
Publication Type: Abstract Only
Publication Acceptance Date: April 28, 1996
Publication Date: N/A
Technical Abstract: Overnight chilling significantly alters the expression of several nuclear genes the encode chloroplast proteins in chilling sensitive plants species. In this study, we found that the steady state level of rubisco activase (rca) mRNA in tomato is substantially decreased during the recovery phase following overnight chilling even through the half-life of rca mRNA is more than doubled by the treatment. This behavior indicates that the lower steady state rca mRNA level may be caused by lower rates of transcription. Two inhibitors of protein phosphatases 1 (PP1) and 2A (PP2A), okadaic acid and calyculin A, were found to prevent the decrease in rca message level following chilling. This result possibly indicates that chilling interferes with the normal expression of rca, and probably certain other genes, by disrupting a phosphorylation/dephosphorylation regulatory step involved in the initiation of transcription. Although the steady state level of rca message decreased following chilling, the level of mRNA associated with polysomes remains high and near the control level. Immunoprecipitation of the polysome runoff products by rca antisera further indicates that chilling treatment may also interfere with the elongation steps in the translation process. A partial length cDNA of rca was cloned by asymmetric PCR, and showed high sequence homology with tobacco and spinach rca. We will use this clone as a probe to isolate the genomic DNA of rca in order to further investigate the detailed mechanism of how chilling effects the expression of rca. This work was supported in part by a grant from the USDA NRI program (grant No. 91-37100-6620).