Med16/SFR6 is Necessary but not Sufficient for COR Gene Ex-Pression of Cbf Pathway

Abstract

Developing stress tolerant crops to cope with the rapid environmental degradation that is occurring is an absolute requirement in order to provide enough food for growing population. One of the basic genetic engineering approaches currently being used to improve crop stress tolerance is generation of transgenic plants by introducing novel genes into the genome of agriculturally important crops or altering the expression of existing genes. Understanding stress response signaling pathways is the prime requirement to manipulate stress tolerance of crop plants by this approach. SFR6 (SENSITIVE TO FREEZING6) is one of plant mediator protein which has identified first with its involvement to tolerance against freezing in Arabidopsis. The freezing sensitivity of SFR6 mutant is lack of expression of downstream genes in CBF cold response pathway. SFR6 also mediates tolerance to osmotic stress induced by drought and salinity. However, the over expression of SFR6 in wild type Arabidopsis did not increase COR (Cold on regulated) gene expression under ambient temperature. Therefore, the effect of SFR6 on cold gene expression was further characterized in this study. Results showed that over expression of SFR6 did not alter CBF1 expression levels under ambient temperature as well as COR gene expression under cold and osmotic stress indicating SFR6 alone cannot use as a molecular tool to improve stress tolerance of crop plants. Further over expression of both SFR6 and CBF1 also did not have additive effect on COR gene expression. Therefore, further studies of the mechanism of SFR6 on COR gene regulation need to be conducted to evaluate the potential of use of SFR6 as a molecular tool to increase stress tolerance of crop plants.