|KARKI, AMRIT - University Of Alabama|
|SUTTON, FEDORA - South Dakota State University|
Submitted to: Functional and Integrative Genomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/22/2012
Publication Date: 3/1/2013
Citation: Karki, A., Horvath, D.P., Sutton, F. 2013. Induction of DREB2A pathway with repression of E2F, Jasmonic acid biosynthetic and photosynthesis pathways in cold acclimation specific freeze resistant wheat crown. Functional and Integrative Genomics. 13:57-65.
Interpretive Summary: Placing winter wheat in cold non-freezing temperatures for an extended amount of time results in both cold acclimation (the ability of the plant to survive freezing temperatures) and vernalization (the ability of the plant to flower and produce seeds during the following growing season). It is difficult to separate the physiological effects due to vernalization from those of cold acclimations. Here, we have used two sister mutant plants that only differ in their ability to cold acclimate but have the same vernalization capacity to examine how extended cold treatments results in cold acclimation. To understand how cold treatment effects these two related varieties, we have examined more than 30,000 genes to see which ones are turned on or off in response to cold in these two varieties. By looking at the function of the genes that are turned on and off, we can determine both how these two varieties differ in the way they detect and respond to low temperatures. Form this data, we identified a system commonly associated with cold responses in other plants that was different between the two varieties. Additionally, we identified a connection between cold responses and growth that was not previously known, and a possible connection to common plant stress response hormone (Jasmonic acid) and also differences in the level at which the two varieties turn down photosynthesis in response to the cold.
Technical Abstract: Winter wheat lines can achieve cold acclimation (development of tolerance to freezing temperatures) and vernalization (delay in transition from vegetative to reproductive phase) in response to low non-freezing temperatures. To describe cold acclimation specific processes and pathways, we utilized cold acclimation transcriptomic data from two lines varying in freeze survival but not vernalization. These lines, designated freeze resistant (FR) and freeze susceptible (FS), were the source of RNA from the crown tissue, the most freeze resistant part of the plant. Well annotated differentially-expressed genes (p = 0.005 and fold change = 2 in response to 4 wk cold acclimation) were used for Gene Ontology (GO) and pathway analysis. “Abiotic stimuli”, was identified as the most enriched and unique for FR. Unique to FS was “cytoplasmic components”. Eight pathways were identified as enriched for FR and one for FS. “Neighbors of DREB2A” was the most enriched of FR pathways and had the highest positive fold change. The “Jasmonic acid biosynthesis” pathway was down-regulated more in FR than in FS. However the “13-LOX and 13-HPL” and the E2F pathways were detected as cold-acclimation regulated only in FR. Four photosynthesis-associated pathways were also down regulated more in FR than in FS. A pathway unique to FS was “Binding partners of LHCA1” which was significantly down regulated in FS but undetected as cold-acclimation regulated in FR. Our results suggest roles for DREB2A, E2F, Jasmonic acid biosynthesis and photosynthetic activities specifically with respect to cold acclimation as associated with freeze survival of winter wheat.