Poster: Temperature responses

Abs # 170: Analysis of the RootCAR1 Promoter in Alfalfa (Medicago sativa L.) Mesophyll and Root Tissue Protoplasts

Presenter:	Singa, Rama Priya N, Contact Author
Authors	Singa, Rama Priya N (A)   Cunningham, Susan M (B)   Volenec, Jeff J (B)   Gana, Joyce A (A)
Affiliations:	(A): Chicago State University (B): Purdue University

Plant growth, development, and productivity are greatly affected when plants are exposed to environmental stresses such as cold, dehydration, and salinity. Plants have evolved complex biochemical and molecular mechanisms to cope with these stressful environments. Plant exposure to low temperature stress, in particular, induces expression of several genes, referred collectively as stress-inducible. The functions of these stress-inducible genes are largely unknown. Alfalfa taproots have a cold stress-inducible gene, RootCAR1 (Cold Acclimation Responsive),whose steady-state transcript levels increase disproportionately in fall-dormant, winter-hardy alfalfa when compared to fall non dormant and freeze susceptible alfalfa genotypes during the cold acclimation period in autumn. The RootCAR1 upstream region contains four Absciscic acid (ABA) core elements ACGT, one of which is a G-box known to be stress-inducible in plants. We hypothesized that RootCAR1 promoter would be inducible under cold stress and exogenous ABA treatment. A vector containing the RootCAR1 promoter along with reporter genes, GFP and GUS, was constructed and introduced into alfalfa protoplasts isolated from fall-dormant and fall-non dormant alfalfa leaf mesophyll and root tissue cells by the polyethylene glycol method. Protoplasts were challenged with cold treatment at 4oC, and ABA. Protoplast was examined for reporter gene expression by florescence microscopy. Inducibility of the RootCAR1-GUS/GFP promoter under cold stress and exogenous ABA treatments is being determined and will be discussed. Results may reveal the differential regulation of the RootCAR1 promoter in alfalfa that vary with respect to fall dormancy reaction and freeze tolerance. This work was supported by NIH grant SO6 GM008043.