TY - JOUR
T1 - Squash xylem sap has activities that inhibit proliferation and promote the elongation of tobacco BY-2 cell protoplasts
AU - Kuroha, Takeshi
AU - Sakurai, Masato
AU - Satoh, Shinobu
N1 - Funding Information:
This work was supported, in part, by a Grant-in-Aid from the “Research for the Future” Program, of the Japanese Society for the Promotion of Science (JSP-RFTF97L00601).
PY - 2005/5
Y1 - 2005/5
N2 - To elucidate the physiological functions of the substances in xylem sap, we analyzed the biological activities of xylem sap from squash (Cucurbita maxima Duch.) root using tobacco BY-2 (Nicotiana tabacum L. cv. Bright Yellow 2) cell protoplasts. When BY-2 cell protoplasts were cultivated with the total substance of squash xylem sap, the protoplasts elongated remarkably, and cell division was inhibited. Although trans-zeatin riboside (ZR), the most abundant cytokinin in squash xylem sap, had a concentration-dependent effect similar to that of total squash xylem sap, ZR concentrations several orders of magnitude greater than those found endogenously in squash xylem sap (i.e. 2 × 10 -8:M) were required to affect the growth of BY-2 cell protoplasts. The ability to stimulate cell elongation and inhibit cell division in BY-2 cell protoplasts was observed for the ethyl acetate phase fraction (pH 2) of squash xylem sap and an acetonitrile-eluate fraction from reverse-phase chromatography. The xylem sap also showed inhibitory activity for auxin-induced elongation of excised cucumber hypocotyls. These results suggest that an organic substance other than ZR is produced in the root and transported to above-ground organs through the xylem via the transpiration stream, where it is involved in regulating cell proliferation and elongation in the shoot, possibly as an auxin antagonist.
AB - To elucidate the physiological functions of the substances in xylem sap, we analyzed the biological activities of xylem sap from squash (Cucurbita maxima Duch.) root using tobacco BY-2 (Nicotiana tabacum L. cv. Bright Yellow 2) cell protoplasts. When BY-2 cell protoplasts were cultivated with the total substance of squash xylem sap, the protoplasts elongated remarkably, and cell division was inhibited. Although trans-zeatin riboside (ZR), the most abundant cytokinin in squash xylem sap, had a concentration-dependent effect similar to that of total squash xylem sap, ZR concentrations several orders of magnitude greater than those found endogenously in squash xylem sap (i.e. 2 × 10 -8:M) were required to affect the growth of BY-2 cell protoplasts. The ability to stimulate cell elongation and inhibit cell division in BY-2 cell protoplasts was observed for the ethyl acetate phase fraction (pH 2) of squash xylem sap and an acetonitrile-eluate fraction from reverse-phase chromatography. The xylem sap also showed inhibitory activity for auxin-induced elongation of excised cucumber hypocotyls. These results suggest that an organic substance other than ZR is produced in the root and transported to above-ground organs through the xylem via the transpiration stream, where it is involved in regulating cell proliferation and elongation in the shoot, possibly as an auxin antagonist.
KW - Cell division
KW - Cell elongation
KW - Root
KW - Squash (Cucurbita maxima Duch.)
KW - Tobacco BY-2 (Nicotiana tabacum L. cv. Bright Yellow 2)
KW - Xylem sap
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U2 - 10.1016/j.plaphy.2005.03.011
DO - 10.1016/j.plaphy.2005.03.011
M3 - Article
C2 - 15890518
AN - SCOPUS:20444401607
VL - 43
SP - 465
EP - 471
JO - Plant Physiology and Biochemistry
JF - Plant Physiology and Biochemistry
SN - 0981-9428
IS - 5
ER -