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Gibberellin-like activity in berries of both ;Tokay' (seeded) and ;Seedless Tokay' grapes (Vitis vinifera L.) at different stages of development was determined. Activity in both seeded and seedless berries was mainly in the acidic ethyl acetate fraction. In seeded berries there was very high activity beginning at the early fruit-set stage and persisting for about 3 weeks after which the activity fell to low level and vanished by the middle of July. On August 1 there was another activity peak. The activity in ;Seedless Tokay' was similar except the decline was considerably more rapid and a secondary peak was reached in mid-June instead of August. The gibberellin-like substances in the acidic ethyl acetate fraction occurred mainly between R(F) 0.3 and 0.6 when the chromatogram was developed with ammoniacal isopropanol.The gibberellin-like substances from both types of berries were active in dwarf pea, dwarf corn, and lettuce hypocotyl bioassays, but not in the cucumber hypocotyl test. The role of gibberellin-like substances in berry development is discussed.

Roots of Vitis vinifera L., were treated with benzyladenine when the plant shoots were 38 cm long. Seventy-two hours after benzyladenine treatment, apical or basal leaves on separate shoots were exposed to (14)CO(2). Control shoots received (14)CO(2) but no benzyladenine. Application of benzyladenine directed (14)C-photosynthate to roots, but a small amount of radioactivity was detected in the shoot tip when (14)CO(2) was administered to an apical leaf. Distribution of radioactivity among the sugar, organic acid, and amino acid fractions was altered by benzyladenine treatment. In all parts of plants with roots treated with benzyladenine and apical leaf fed (14)CO(2), the percentage of the total label in the sugar fraction comprised of fructose was generally more than twice that in control plants.

Leaves of Vitis vinifera L., nearly fully expanded, imported only trace amounts of (14)C following assimilation of (14)CO(2) by a lower leaf on the same shoot, but benzyladenine (BA) application at 4.4 x 10(-3)m caused a marked increase in the movement of (14)C into these leaves. Older leaves near the shoot base were less responsive; BA treatment alone had little effect on import of labeled assimilates from adjacent leaves but when the BA-treated leaves were darkened there was an increased import of labeled materials. When these 2 treatments were combined and applied to leaves on shoots with ringed bases, relatively high levels of radioactivity were detected in the BA-treated leaves but under these conditions darkening, without the application of BA, also resulted in an increased import of (14)C. Accumulation of imported (14)C was found to be restricted to the area of the leaf blade treated with BA. Separation of labeled compounds in ethanol extracts of treated leaves showed a lower percentage of radioactivity present in the sugar fraction from BA-treated leaves and an increased percentage present in the amino acid fraction.

The effect of exogenous growth regulators on movement of assimilates into flowers and young fruits of ;Black Corinth' grapes was studied. Clusters were treated with growth regulator and after 0.5 hr to 5 days the leaves above the clusters were exposed to (14)CO(2). Control shoots received (14)CO(2) but no growth regulator. At harvest, counting and radioautographic techniques were used to ascertain amount and distribution of activity in clusters. Clusters were dipped in 4-CPA (4-chlorophenoxyacetic acid), GA(3) (gibberellic acid), or BA (benzyladenine). All berries were heavier than controls within 3 days. Total counts in the fruits were increased by 4-CPA, and the distribution of radioactivity among the sugar, organic acid, and amino acid fractions was usually altered by all treatments. In a time series experiment, within 6 hr after treatment of fruits with GA(3) there was almost an 8-fold increase in total counts relative to the control. After 12 hr there was about a 9-fold and 6-fold increase in counts in tartaric and malic acids, respectively, and in gamma-aminobutyric acid, pipecolic acid, and valine increases of 56, 150, and 330%. Radioactivity in fructose was increased 70% in gibberellin-treated clusters over the controls. After 96 hr there were only about 1000 cmp per g fr wt in controls, but there were about 31,000 cpm counts in treated clusters. Treatment of clusters with gibberellin attracted less assimilates into the fruits when shoots had also been sprayed with gibberellin. Dipping portions of clusters in gibberellin increased the movement of (14)C assimilates into the treated portions. Hormonal control of mobilization is discussed.

During the prebloom and bloom stages, no movement of labeled photosynthates occurred from a shoot of Vitis vinifera L. fed with (14)CO(2), to an adjacent shoot on the same spur. Movement of labeled assimilates into the unfed shoot was induced when this shoot was sprayed with 2.89 x 10(-3)m gibberellic acid during the prebloom stage. During the bloom stage darkening or defoliation of the unfed shoot resulted in the import of labeled photosynthates from the adjacent fed shoot. Similarly, movement of (14)C into an untreated shoot was induced by removing the terminal 7.5 centimeters and deblossoming the fed shoot. During the berry set stage, translocation of labeled photosynthates from a newly exporting leaf was upwards to the shoot tip, but the direction of movement was reversed by removal of the shoot tip or by darkening or removal of the leaves below the fed leaf. Translocation of photosynthates was predominantly basipetal from a fed leaf near the base of the shoot during the berry set stage, but upward movement was induced by darkening or defoliation of the upper part of the shoot.