|Liu, Hong - PLANT BIOLOGY UOFI URBANA|
Submitted to: American Society of Plant Physiologists Meeting
Publication Type: Abstract Only
Publication Acceptance Date: February 5, 1999
Publication Date: N/A
Technical Abstract: Earlier work has shown that in chilling-sensitive plants low temperature can induced a delay of the circadian timing of gene expression. We examined protein profiles following pulse labeling with radiolabeled methionine comparing plants that had been chilled for 16 h at 4oC to controls that had been maintained at room temperature in the dark for 16 h. Several, seemingly novel proteins are changed by the chilling treatment including one rapidly turning over, heavily-labeled polypeptide that runs at 35 kDa (p35) on SDS-PAGE. The normal diurnal expression pattern of this tomato leaf protein reveals that it is actively synthesized in the late afternoon. We isolated and micro sequenced two internal fragments of p35 protein as well as cloned the full length cDNA sequence of p35 gene in tomato. It does not show high homologous with any known gene. Northern blots probed with this clone show that the expression of p35 gene has a diurnal rhythm with a high expression in the late afternoon. RNA level of p35 gene also shows a strong circadian rhythm during 3 days of constant darkness. Chilling delays the expression of p35 transcript whether chilling exposure starts at the lowest or highest point in circadian expression pattern. The role of protein phosphorylation in the chilling effect on the circadian regulation of p35 gene expression was also studied.