GDCB Professor Stephen Howell and His Research Team Study Stress Tolerance in Plants
February 28, 2014
GDCB Professor Stephen Howell is senior of a paper recently published in the Proceedings of the National Academy of Sciences that may shed new light on the genetic mechanisms that allow plants to protect themselves from environmental stress, which could lead to improved stress tolerance in cash crops. (ISU News Release)
The two arms of the ER stress-response signaling pathway in plants (see image at right). One arm involves membrane-associated transcription factors such as bZIP28; the other involves a membrane-associated dual protein kinase/ribonuclease, IRE1, which splices the mRNA encoding bZIP60. In response to stress, bZIP28 and IRE1 are activated by the accumulation of misfolded proteins in the ER. bZIP28 is mobilized from the ER and transported to Golgi bodies, where it is progressively processed by site 1 and site 2 protease (S1P and S2P). S2P intramembrane cleavage releases the N-terminal component of bZIP28 into the cytosol, allowing it to relocate to the nucleus. Once activated, IRE1 splices the bZIP60-encoding mRNA, creating a frameshift such that the spliced RNA now encodes a transcription factor with a nuclear targeting signal. bZIP28 and bZIP60 can heterodimerize, and it is thought that the two arms of the signaling pathway may converge in the formation of heterodimers that can upregulate stress-response genes.