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ARS Home » Plains Area » Fargo, North Dakota » Edward T. Schafer Agricultural Research Center » Sugarbeet and Potato Research » Research » Publications at this Location » Publication #304725
Title: Biochemical properties and expression analysis of potato cytokinin oxidases during tuber dormancy

Author
item Suttle, Jeffrey
item Young, Linda

Submitted to: American Journal of Potato Research
Publication Type: Abstract Only
Publication Acceptance Date: 4/18/2014
Publication Date: 4/4/2015
Citation: Suttle, J.C., Olson, L.L. 2015. Biochemical properties and expression analysis of potato cytokinin oxidases during tuber dormancy [Abstract.] American Journal of Potato Research. 92:209-210.

Interpretive Summary:

Technical Abstract: At harvest and for an indeterminate period thereafter, potato tubers are dormant and will not sprout. Tuber dormancy is lost during postharvest storage and the subsequent sprouting results in the loss of tuber processing and nutritional qualities. Endogenous cytokinins have been posited to play a pivotal role in the reactivation of tuber meristems during dormancy exit. However, the cognate mechanisms controlling endogenous cytokinin content in tuber buds during dormancy progression are unknown. Cytokinin dehydrogenase/oxidase (CKX) is the principal enzyme of cytokinin metabolism catalyzing the irreversible oxidative cleavage of the N6-isoprenoid side chain of naturally occurring cytokinins. Five CKX-like genes were cloned from tuber bud RNA. Protein extracts from yeast expressing full-length clones of all five CKX-like genes displayed in vitro CKX activity using isopentenyl adenosine and artificial electron acceptors. Both the electron acceptor and substrate preferences of the expressed proteins differed between the five enzymes. Genes encoding all five CKX proteins were expressed in tuber bud tissues during dormancy progression. There was no change in apparent in planta CKX activity during either natural or chemically forced dormancy progression. Similarly although expression of individual StCKX genes varied modestly during tuber dormancy, there was no clear correlation between StCKX gene expression and tuber dormancy status. Thus although CKX gene expression and enzyme activity are present in potato tuber meristems throughout dormancy, they do not appear to play a significant role in the regulation of cytokinin content during tuber dormancy progression.