Poster: Temperature responses

Abs # 172: Determining If Dual TATA Elements in RootCAR1 Promoter Have Functional Alternative Transcription Start Sites in Alfalfa (Medicago sativa L.) Abiotic-Stressed Plants

Presenter:	Milton, Angenee C, Contact Author
Authors	Milton, Angenee C (A)   Cunningham, Susan M (B)   Volenec, Jeff J (B)   Gana, Joyce A (A)
Affiliations:	(A): Chicago State University (B): Purdue University

Plants respond to abiotic stresses such as temperature, drought, and salinity by expressing a number of genes that allow plants to thrive in less-optimal conditions. Often, plant growth and productivity are severely compromised under these abiotic stress conditions. Knowledge of molecular mechanisms involved in plant response to abiotic stresses, in particular, low temperature stress is incomplete. The regulation of a number of low temperature-inducible genes occurs at the transcription level. Transcripts for RootCAR1 (Cold Acclimation Responsive) accumulate differentially in fall dormant, freeze tolerant alfalfa than in non fall dormant and freeze susceptible alfalfa in response to cold temperatures. The upstream promoter region of RootCAR1 contains two TATA-box elements. Few studies have demonstrated the occurrence of multiple TATA elements and use of alternate transcription initiation sites in directing transcription of multiple mRNAs from a single gene in response to various environmental stresses. Our hypothesis is that the dual TATA in the RootCAR1 promoter allows for alternate use of transcription initiation sites as alfalfa responds to low temperature in a tissue-specific manner. To test our hypothesis, RT-PCR analysis was performed on total RNA extracted from three-week-old plants exposed to several abiotic stresses. A preliminary result indicates that only the TATA box closer to the translation initiation codon is functional. Results of the dual TATA functional characterization should reveal different size transcripts from RootCAR1. Alternate transcription start sites in RootCAR1 are used probably to increase the flexibility of gene expression when alfalfa is exposed to less optimal conditions. This work was funded by NIH grant SO6 GM008043