Poster: Temperature responses

Abs # 173: Expression of RootCAR1 in Seedlings of Alfalfa (Medicago sativa L.) exposed to Exogenous ABA, Cold, Dehydration, and Salinity

Presenter:	Quaye, Laura K, Contact Author
Authors	Quaye, Laura K (A)   Cunningham, Susan M (B)   Volenec, Jeff J (B)   Gana, Joyce A (A)
Affiliations:	(A): Chicago State University (B): Purdue University

The abiotic stresses of cold, drought, and salt induce expression of a subset of similar genes indicating that cross-talk occurs in the various stress response pathways. Abscisic acid (ABA), plays a vital role in plant development including maturity, seed germination, dormancy, and response to environmental stresses and accumulates when plants are subjected to abiotic stresses. Exogenous ABA is known to induce a number of genes that are responsive to dehydration, cold, and salt stresses. Therefore our objective is to determine if the alfalfa cold acclimation response gene, RootCAR1, is also induced by exogenous ABA, dehydration, and salt stresses. Seeds of the fall dormant, freeze-tolerant alfalfa cultivar Pioneer 5454, were grown for 3 weeks on MS medium solidified with 0.8% agar under continuous light. Seedlings were either sprayed with solutions of NaCl, mannitol, and ABA, were exposed to 4oC, or were dehydrated in open air. Control plants were sprayed with water alone. Total RNA was isolated from the seedlings and expression of the RootCAR1 gene analyzed using RT-PCR and primers that amplify the 5 prime coding region. RT-PCR products were visualized using ethidium bromide following agarose gel electrophoresis. An expected RootCAR1 RT-PCR product (~200 bp) was obtained in RNA isolated from ABA-, dehydration-, salt-, and mannitol-treated tissues, but surprisingly not the cold-treated plants. Two additional larger size bands besides that of RootCAR1 were obtained in the ABA, salt, and dehydration treated plants suggesting that CAR members also respond to these stresses. These experiments indicate that RootCAR1 is regulated by ABA in alfalfa seedlings perhaps through the ABA-dependent pathway. [This work was supported by NIH grant SO6 GM008043]