Poster: Hormone synthesis & metabolism

Abs # 481: Regulation of ABA biosynthesis during potato tuber dormancy: Molecular characterization of a putative potato ABA2 gene

Presenter:	Destefano-Beltran, Luis J, destefal@fargo.ars.usda.gov
Authors	Destefano-Beltran, Luis J (A)   Knauber, Donna  (A)   Suttle, Jeffrey  (A)
Affiliations:	(A): Northern Crop Science Laboratory, USDA-ARS

At harvest and for an indeterminate period thereafter, potato (Solanum tuberosum L.) tubers will not sprout and are physiologically dormant. A complex interplay of genetic and environmental factors affects the length of this dormant stage. As the period of postharvest storage is extended, tuber dormancy is eventually broken and sprout growth commences. Uncontrolled sprouting is detrimental to both the nutritional and processing qualities of stored potatoes. Endogenous hormones haven been hypothesized to play an important role in tuber dormancy regulation. As currently envisioned, both ABA and ethylene are required for the induction of tuber dormancy but only the sustained synthesis and action of ABA are needed to maintain bud dormancy. The molecular mechanisms regulating ABA synthesis and accumulation in potato tubers are unknown. As part of an on-going effort to determine the roles of ABA biosynthetic genes during the potato tuber dormancy, we have begun the molecular characterization of the potato ABA2 gene that encodes a short-chain (xanthoxal) dehydrogenase enzyme catalyzing the penultimate step in ABA biosynthesis. Primers based on a tentative consensus sequence from tomato with a high homology to the ABA2/GIN1 gene from Arabidopsis were used to obtain a full-length StABA2 cDNA clone from a Russet Burbank potato cell suspension mRNA preparation. Here we present a detailed analysis of the expression of this gene during potato tuber dormancy progression.