Changes in cis-zeatin and cis-zeatin riboside levels and biological activity during potato tuber dormancy.
Suttle, J. C.; Banowetz, G. M.;
Physiologia Plantarum Year: 2000 Vol: 109 Issue: 1 Pages: 68-74 Ref: 31 ref.
2000
บทคัดย่อ
Minitubers of potatoes cv. Russet Burbank were completely dormant for at least 81 days of storage. Thereafter, tuber bud dormancy diminished gradually and after 165 days of post-harvest storage, the tubers were completely non-dormant. Immediately after harvest, endogenous levels of cis-zeatin (cis-Z) and cis-zeatin riboside (cis-ZR) were approximately 25 and 8 pmol/g fresh weight, respectively. In tubers exiting dormancy but stored at a growth-inhibiting temperature (3 deg C), endogenous levels of cis-Z rose over three-fold after 25 days of storage and remained elevated for the duration of the study. Levels of cis-ZR remained essentially constant during this same period. In tubers transferred to a growth-permissive temperature (20 deg C) prior to use, the rise in endogenous cis-Z was less dramatic and more protracted, increasing two-fold after 53 days of storage. No change in cis-Z riboside content was observed in these tubers during this period. Dose-response studies using either cis-Z or trans
-Z demonstrated a time-dependent increase in cytokinin sensitivity during post-harvest storage. Immediately after harvest, dormant tubers were insensitive to both zeatin isomers. Thereafter, tubers exhibited a dose-dependent increase in premature sprouting following injection with either cytokinin isomer. After injection into dormant tubers, cis-[8-14C]-zeatin was metabolized primarily to adenine/adenosine and cis-Z riboside. Seven days after injection, less than 10% of the recovered radioactivity was associated with trans-ZR. These results are consistent with a role for endogenous cis-Z (and its derivatives) in the regulation of potato tuber dormancy.