Growth regulator induced movement of photosynthetic products into fruits of ;black corinth' grapes

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 ¹⁴CO₂. Control shoots received ¹⁴CO₂ 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), GA₃ (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 GA₃ 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 γ-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 ¹⁴C assimilates into the treated portions. Hormonal control of mobilization is discussed.     

Identification of plant hormones from cotton ovules

An extract from 8-day-old cotton ovules (Gossypium hirsutum L.) was partitioned into three fractions and each fraction was derivatized and analyzed separately. Gas-liquid chromatography and computer-controlled gas-liquid chromatography-mass spectrometry were used to separate, measure, and identify the naturally occurring plant hormones. A single extract contained abscisic acid, indoleacetic acid, and gibberellins A(1), A(3), A(4), A(7), A(9), and A(13) in the first fraction; ethyl indole-3-acetate and indole-3-aldehyde in the second fraction; and the cytokinins 6-(3-methyl-4-hydroxybutylamino)purine (dihydrozeatin), 6-(4-hydroxy-3-methyl-2-trans-butenylamino) purine (zeatin), 6-(3-methyl-2-butenylamino)purine(2iP), 6-(3-methyl-2-butenylamino)-9-beta-d-ribofuranosylpurine(2iPA), and 6-(4-hydroxy-3-methyl-2-trans-butenylamino)-9-beta-d- ribofuranosylpurine (zeatin riboside) in the third fraction.     

Benzyladenine-induced Movement of C-Labeled Photosynthate into Roots of Vitis vinifera

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 ¹⁴CO₂. Control shoots received ¹⁴CO₂ but no benzyladenine. Application of benzyladenine directed ¹⁴C-photosynthate to roots, but a small amount of radioactivity was detected in the shoot tip when ¹⁴CO₂ 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 ¹⁴CO₂, the percentage of the total label in the sugar fraction comprised of fructose was generally more than twice that in control plants.     

Absorption and distribution of high specific radioactivity 2-C-abscisic Acid in cotton seedlings

High specific radioactivity (26.3 mc/mmole) racemic 2-¹⁴C-abscisic acid was synthesized. An aliquot of abscisic acid, 1.2 × 10⁻⁴m in aqueous methanolic solution, was applied to the surface of either a cotyledon or the first true leaf of 8- to 32-day-old cotton seedlings (Gossypium hirsutum L.). After various intervals (6-192 hours), the seedlings were processed for autoradiography, counting, and identification of the radioactivity. After 6 hours, radioactivity was observed moving basipetally out of the treated leaf toward the roots. Four days later, radioactivity could be detected throughout the whole seedling. After 8 days, 10% of the recovered radioactivity was found in the roots, and 80% remained in the treated leaf blade. Neither leaf type nor age had any effect on the abscisic acid movement or pattern of distribution. Isolated radioactivity from the roots was identified as abscisic acid, based on comparison with an authentic standard by thin layer chromatography, gas-liquid chromatography, or gas-liquid chromatography-mass spectrometry.     

Analysis of abscission responses to photodecomposition products of 1-naphthaleneacetic acid

This paper presents an analysis of abscission reponses of cottonexplants to (a) 1-naphthaneneacetic acid; (b) photodecompositionproducts of 1-naphthaleneacetic acid: 1-methylnaphthalene, 1-naphthaldehyde,1-naphthoic acid, naphthalene, and phthalic acid; and (c) arelated compound: naphthaleneacetyl aspartate. Abscission wasaccelerated by low amounts and retarded by high amounts of 1-naphthaleneaceticacid and 1-naphthoic acid. No significant effect on abscissionwas observed from 1- methylnaphthalene, 1-naphthaldehyde, orphthalic acid applied in amounts from 10^–8 to 10.0 µgper petiole; or with naphthalene from 10^–3 to 10.0µgper petiole. Naphthaleneacetyl aspartate had no effect at 5?10⁴to 5?10^–3 µg per petiole, but completely inhibitedabscission at 5 ? 10^–1 and 5.0 µg per petiole. Thedata are analyzed on part by a previously described mechanicalmethod for the determination of abscission indexes, and in partby a new method described herein, using a digital computer forthe analysis of the abscission time-course data. The resultshave significance to the understanding of the variability encounteredin fruit thinning by 1-naphthaleneacetic acid and related substances,and are discussed in relation to the known intermediate effectsof 1-naphthaleneacetic acid in fruit thinning. ¹Present address: Department of Biology, Univesity of California,Riverside, California 92502, U.S.A. (Received August 26, 1972; )