Gibberellin-like substances in root exudate of Vitis vinifera.

The levels of gibberellin (GA)-like activity in the root exudate of two seedless varieties of Vitis vinifera were examined by the barley endosperm assay, and compared with levels determined for other parts of the plant. That activity was due to GA-like substances was confirmed with dwarf-5 corn.When acidic, ethyl acetate soluble GA-like substances from sap and leaf extracts were chromatogrammed on thin layers of silica gel in chloroform/ethyl acetate/formic acid (50:50:1), activity moved to the same Rf as GA3 and GA1 (Rf 0.05-0.25). However, substances inhibitory to the barley endosperm assay were detected in both sap and leaf extracts. In the above solvent system the inhibitor(s) co-chromatogrammed with a GA1/GA7 mixture, and with abscisin II. The GA-like activity co-chromatogrammed with GA3 on paper developed in isopropanol/ammonia/water (10:1:1).Calculations on the rate of gibberellin movement from the roots seemed to be compatible with levels of activity in the leaves, although these levels could also be a reflection of the general gibberellin level in the plant.The relevance of the findings is discussed.