The role of polyamines in potato tuber formation |
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Authors: | Calixto M Protacio Hector E Flores |
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Affiliation: | (1) Department of Plant Pathology and Biotechnology Institute, The Pennsylvania State University, 315 Wartik Laboratory, 16802 University Park, Pennsylvania |
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Abstract: | Summary The involvement of free and conjugated polyamines in tuber formation was studied in in vitro cultured node explants ofSolanum tuberosum cv. Superior. Tubers developed from the axillary buds in 100% of the explants cultured in MS medium containing high sucrose
levels and supplemented with kinetin (Kin) and chlorocholine chloride (CCC). The addition of growth regulators was not essential
for tuber formation, although smaller tubers were formed in the medium devoid of Kin and CCC. Tuber formation was inhibited
in about 75% of node explants treated with 0.5 mM difluoromethylornithine (DFMO), a specific and irreversible inhibitor of ornithine decarboxylase. The inhibitory effect of
DFMO was almost completely reversed by putrescine addition. Addition of difluoromethylarginine (DFMA), the analogous inhibitor
of arginine decarboxylase, had no effect on tuber formation. DFMO, but not DFMA, also inhibited the development of axillary
buds into shoots in light-grown node explants. Aminooxyphenylpropionic acid (0.1 to 0.25 mM), an inhibitor of phenylalanine ammonia lyase, caused a sharp reduction in cinnamoyl putrescines, but had no effect on tuber
formation. Our results suggest that hydroxycinnamic acids are not causal in tuber formation but may serve as polyamine storage
pools. Our findings support the hypothesis that polyamines derived via the ornithine decarboxylase-mediated pathway are necessary
for tuber formation in vitro, probably at the early phase of morphogenesis involving active cell division. |
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Keywords: | Solanum tuberosum in vitro tubers polyamines cinnamoyl putrescine hydroxycinnamic acid amides putrescine inhibitors aminooxyphenylpropionic acid |
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