Date of Award


Document Type

Honors Thesis (Open Access)


Colby College. Biology Dept.


Russell R. Johnson

Second Advisor

Ronald F. Peck

Third Advisor

Judy L. Stone


The hormones gibberellin and abscisic acid are essential for plant responses to changing environmental conditions, and can send opposing signals. In wheat, the transcription factor TaABF1 plays an important role at the intersection of a gibberellin-induced/abscisic acid-suppressed pathway. When gibberellin dominates, the GA-induced gene, Amy32b, is transcribed. When abscisic acid is dominant, TaABF1 is active and it downregulates GA-induction of Amy32b, while promoting ABA-induced transcription of the gene HVA1. The activity of TaABF1 is thought to be regulated by post-translational phosphorylation at key serine residues. In this study, to determine TaABF1 phosphorylation by wheat kinases, we purified recombinant histidine tagged TaABF1 protein, incubated it with kinases extracted from the aleurone layer of wheat grains, and assessed phosphorylation status using liquid chromatography-mass spectrometry. We have designed a successful purification scheme, and are able to identify synthetic test peptides and peptides that result from tryptic digestion of BSA and purified un-phosphorylated TaABF1. However, we are still working to optimize protein recovery after the phosphorylation assay for analysis by liquid chromatography-mass spectrometry.


TaABF1, gibberellin, abscisic acid, kinase, wheat, phosphorylation

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