GIBBERELLIN-LIKE SUBSTANCES IN ROOT EXUDATE OF VITIS VINIFERA

The levels of gibberellin (GA)-like activity in the root exudate of 2 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[long dash]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 GA4/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.