Poster: Regulation of gene expression

Abs # 800: Expression of the Solanaceous CBF Gene Family in Response to Light and Temperature in Lycopersicon and Solanum Spp differing in Cold Tolerance

Presenter:	Pennycooke, Joyce C., pennycooke.1@osu.edu
Authors	Pennycooke, Joyce C. (A)   Stockinger, Eric J (A)
Affiliations:	(A): Ohio State University, Department of Horticulture and Crop Science

Plants vary in their ability to survive low temperatures in response to cold acclimation (CA), a process whereby plants increase their tolerance to freezing after exposure to low, non-freezing temperatures. CA is the result of cold regulated genes, the C-Repeat Binding Factor (CBF) and the CBF regulon. Expression patterns of the Solanaceous CBF gene family in response to light and temperature were examined in spp differing in cold tolerance. Tomato, like Arabidopsis contains a functional CBF gene that is cold responsive and activates transcription of the CRT/DRE regulated genes. However, unlike Arabidopsis, only one (LeCBF1) of the three CBF genes is cold- induced. A significant finding in the study is that CBF induction by cold occurs only after a period of light exposure (ca. 6h) before the cold treatment. The transcript level is not detectable in the absence of cold. However, it increases rapidly with a cold treatment and reaches a maximum after 8 or 24h depending upon the genotype. Transcripts disappear within 24h of deacclimation. The levels of low temperature tolerance varied among plants, with Solanum commersonii and Lycopersicon hirsutum being the most tolerant and Solanum cardiophylum and Lycopersicon pimpinellifolium being the least tolerant Solanum and Lycopersicon spp respectively. Although the induction of low temperature tolerance is dependent upon exposure to cold, we found that further increases in low temperature tolerance in TA491 is clearly light dependent. Light may act as a signal in activating certain chilling tolerance mechanisms including the expression of CBF. The low level of CBF cold induction in L. pimpinellifolium and S. tuberosum is not due to their absence in the genome but may be due to differences in their structural organization.