Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: May 16, 2005
Publication Date: June 1, 2005
Citation: Destefano Beltran, L.J., Knauber, D.C., Huckle, L.L., Suttle, J.C. 2005. Changes in aba biosynthetic and metabolism-related gene expression during meristem dormancy in potato tubers [ abstract.] Plant Sciences Institute "Meristems 2005." Abstract No. 25 p.34. Technical Abstract: At harvest and for an indeterminate period thereafter, potato tubers will not sprout and are physiologically dormant. Although the underlying molecular mechanisms controlling tuber dormancy are poorly understood, it has been proposed that endogenous plant hormones are intricately involved in potato tuber dormancy control. In particular, abscisic acid (ABA) has been established to play a vital role in tuber dormancy induction and maintenance. ABA content is highest immediately after harvest and declines thereafter. Treatment of developing microtubers with the ABA biosynthesis inhibitor fluoridone results in a drastic reduction of endogenous ABA content and premature sprouting. Exogenous ABA restores ABA levels and prevents precocious sprouting. The fundamental mechanisms controlling ABA biosynthesis and metabolism in tubers are unknown. Genes encoding for all post-zeaxanthin steps of ABA biosynthesis and ABA catabolite phaseic acid formation (three P450-like isoforms) have been cloned and characterized from potato tubers. Expression of these genes was analyzed using RT-qPCR from meristems sampled from dormant tubers and during dormancy progression. The results indicate that transcripts of the biosynthetic genes are down-regulated as the meristems leave dormancy. On the other hand, the transcripts of two out of three P450-like metabolizing enzymes are up-regulated as the meristems become non-dormant. Similar results have been obtained with dormant tubers treated with bromoethane (BE) to artificially break dormancy.