INFLUENCE OF ULTRAVIOLET RADIATION ON AUXIN-CONTROLLED PLANT GROWTH'

A B S T R A C T Ultraviolet irradiation (254 m,) of plant test systems results in alterations in growth capacity which can be ascribed to UV-induced modifications of the ability of plant cells to respond to auxin. This conclusion was reached following study of auxin-requiring, auxin-sufficient, and auxinsurfeit test systems representing cell division, cell enlargement, and cell differentiation. The UV effect was usually reversible by subsequently presented near-visible or visible radiation. ALTHOUGH the growth-promoting effect of mid-ultraviolet radiation (200-300 m,u) on plants was known for many years (Popp and Brown, 1936), it remained for deZeeuw and Leopold (1957) to show that part of this suppression might be due to an effect on auxin metabolism. Using epinasty in tomato and elongation of pea stem segments, deZeeuw and Leopold found that the radiation reduced the responses of test plants to auxin supplied after radiation. Garay and Sagi (1962) found that mid-UV prevented the auxin-induced elongation of hypocotyls of Lupinus alba and of Avena coleoptiles. Based on limited experiments, both groups concluded that the radiation did not affect the endogenous level of auxins or the uptake of auxin by plant tissues, and they suggested that UV radiation might modify the capacity of tissues to use available auxin. The potential importance of these findings to elucidation of the role of auxin in growth suggested that these studies should be confirmed and extended. To this end, plant systems known or presumed to have an absolute requirement for auxin (auxin-requiring), systems known or presumed to make the auxin they require (auxinsufficient), and systems known or presumed to contain supra-optimal levels of auxin (auxinsurfeit) were selected for study. Three auxinrequiring systems were used: coleoptile elongation, in vivo abscission of Coleus petioles, and in vitro pulvinus abscission of bean. Two auxinsufficient systems were used: cell division of the cell aggregates of an habituated strain of Ginkgo pollen tissue culture and formation of adventitious hypocotyledonary buds of decapitated flax seedlings. Three auxin-surfeit systems were used:

[1]  H. Spang.  The Implication of Auxin in the UV Promoted Expansion of Etiolated Bean Leaf Disks , 1966 .

[2]  R. M. Devlin,et al.  EFFECTS OF INDOLE‐3‐ACETIC ACID AND PARACHLOROPHENOXY‐ISOBUTYRIC ACID ON ABSCISSION IN PETIOLES OF DEBLADED LEAVES OF PHASEOLUS VULGARIS , 1966 .

[3]  P. Wareing,et al.  Auxin and Kinetin Interaction in Apical Dominance , 1966, Science.

[4]  R. Klein.  Photomorphogenesis of the Beau Plumular Hook , 1965 .

[5]  R. S. Mellor,et al.  Influence of Light Regime on the Toxicity and Physiological Activity of Herbicides. , 1965, Plant physiology.

[6]  B. Gabrielsson,et al.  Localization of Reactivation after UV-Inhibition of Root Growth , 1964 .

[7]  A. Leopold,et al.  Kinetin and Gibberellin Actions on Abscission Processes. , 1964, Plant physiology.

[8]  C. Gorter.  Studies on Abscission in Explants of Coleus , 1964 .

[9]  E. Libbert.  Kontrolliert Auxin die Apikaldominanz , 1964 .

[10]  R. Klein.  Interaction of Ultraviolet and Visible Radiations on the Growth of Cell Aggregates of Ginkgo Pollen Tissue , 1963 .

[11]  R. Klein,et al.  Effects of Non-Ionizing Radiation on Expansion of Disks From Leaves of Dark-Grown Bean Plants. , 1963, Plant physiology.

[12]  W. Jacobs.  Longevity of Plant Organs: Internal Factors Controlling Abscission , 1962 .

[13]  F. Satu,et al.  Effect of UV‐Radiation on the Auxin‐Auxinoxidase‐Phenol Complex and on the Sensitivity of Plant Tissues to Indoleacetie Acid , 1962 .

[14]  J. Lockhart.  The Response of Various Species of Higher Plants to Light and Gibberellic Acid , 1958 .

[15]  D. Dezeeuw,et al.  THE PREVENTION OF AUXIN RESPONSES BY ULTRAVIOLET LIGHT , 1957 .

[16]  J. L. Liverman,et al.  Effect of Radiation and Growth Regulators on Leaf Abscission in Seedling Cotton and Bean. , 1956, Plant physiology.

[17]  P. Ray,et al.  The Base Curvature Response of Avena Seedlings to the Ultraviolet , 1956 .

[18]  W. Klein,et al.  Response of the Hypocotyl Hook of Bean Seedlings to Radiant Energy and Other Factors. , 1956, Plant physiology.

[19]  N. Yamada.  Auxin Relationships of the Rice Coleoptile. , 1954, Plant physiology.

[20]  A. Schrank,et al.  Electrical and curvature responses of the Avena coleoptile to unilateral ultraviolet irradiation. , 1954, Journal of cellular and comparative physiology.

[21]  R. T. Brumfield.  CURVATURES IN TIMOTHY ROOTS INDUCED BY ULTRAVIOLET RADIATION , 1953 .

[22]  H. Lacey,et al.  STUDIES IN THE MORPHOGENESIS OF LEAVES: IX. EXPERIMENTS ON LEMNA MINOR WITH ADENINE, TRIIODOBENZOIC ACID AND ULTRA‐VIOLET RADIATION , 1953 .

[23]  R. Wetmore,et al.  STUDIES ON ABSCISSION: THE INHIBITING EFFECT OF AUXIN , 1953 .

[24]  F. Addicott,et al.  Acceleration and retardation of abscission by indoleacetic acid. , 1951, Science.

[25]  T. Hemberg.  Rooting Experiments with Hypocotyles of Phaseolus vulgaris L. , 1951 .

[26]  K. Thimann,et al.  The effect of auxin on flower initiation. , 1949, American journal of botany.

[27]  R. Klein.  Influence of 2,4-Dichlorophenoxyacetic Acid on Initiation and Development of Hypocotyledonary Buds of Decapitated Flax , 1948, Botanical Gazette.

[28]  V. Eggers.  The Effect of Indoleacetic Acid upon Initiation and Development of Hypocotyledonary Bud Primordia in Flax , 1946, Botanical Gazette.

[29]  V. Eggers.  Mode, Site, and Time of Initiation of Hypocotyledonary Bud Primordia in Linum usitatissimum L. , 1946, Botanical Gazette.

[30]  H. F. Rosene.  COMPARISON OF RATES OF WATER INTAKE IN CONTIGUOUS REGIONS OF INTACT AND ISOLATED ROOTS. , 1941, Plant physiology.

[31]  R. S. Choudhri,et al.  Growth Studies in Relation to Ultraviolet Radiation , 1936, Botanical Gazette.

[32]  D. M. Crooks.  Histological and Regenerative Studies on the Flax Seedling , 1933, Botanical Gazette.