Richard M. Klein

Plants and near-ultraviolet radiation

ConclusionsThat the near UV has profound effects on biological material in general and plants in particular seems well established, but the implications of these findings in plant biology seem not to have been exploited. With a significant proportion of the solar spectrum at the earth’s surface in the 280–390 nm range the effects of near-UV wavelengths on ecosystems and in biosystematics should be considered. There is some evidence that alpine flora has, over evolutionary time, become adapted to the increased intensities of near UV, but whether this is a cause/effect situation has not been determined. The known ability of near UV to cause alterations in genomes-explored to date primarily in procaryotes-needs to be examined in vascular plants as a possible cause in ecotypic variation and as a factor in somatic and genome mutation.One is struck by the paucity of information now available on the receptor systems for the various near-UV wavelengths known to affect physiological and biochemical systems within plants. Cells of higher plants contain many compounds capable of absorbing near-UV radiation and capable of reacting by excitation, photodegradation, photo-oxidation, etc., but in only a few instances have the photoreceptors for observed biological reactions been unequivocally identified and in almost none of these cases has the chain of reactions leading from absorption to observable reaction been traced with any assurance. In part, these lacunae in our knowledge are due to our ignorance of just what cells really do, but there is also a gulf between the information accumulated by the photochemist or photophysicist and that known to the botanist. One obvious example of this is the general failure of the photobiologist to specify adequately the physical parameters of their experiments; merely stating that near-UV “light” was supplied is grossly inadequate.To end on an upbeat, it should be pointed out that plant photobiology is of growing importance in all areas of botany, that the instrumentation and techniques are now available, and that the concepts that must form the basis for research are at hand.ConclusionsIl semble donc bien établi que les proches rayons ultraviolets aient des effets profonds sur la matière biologique en général et sur les plantes en particulier, mais on n’a pas encore exploité les implications de ces découvertes dans la biologie des plantes. Etant donné la part importante du spectre solaire à la surface de la terre qui se trouve entre 280 et 390 nm, on devrait aussi examiner les effets des proches rayons ultraviolets en biosystématique et sur les écosystèmes. On a constaté que dans une cortaine mesure la flore alpine, à travers les âges évolutionnaires, s’était adaptée aux intensités grandissantes des proches rayons ultraviolets, mais on n’a jamais pu établir si c’était une relation de cause à effet. C’est un fait bien établi que les proches rayons ultraviolets altèrent les formations héréditaires-et ceci a été essentiellement étudié jusqu’à maintenant dans les procaryotes-mais en devrait aussi étudier leur action sur les plantes vasculaires pour savior s’ils sont à l’erigine de variations écotypiques et s’ils contribuent à la mutation somatique et génétique.On est frappé par l’insuffisance de renseignements disponibles à l’égard des systèmes récepteurs des proches rayons ultraviolets qui sont connus pour leur effet sur les systèmes biochimiques et physiologiques des plantes. Les cellules des plantes supérieures contiennent de nombreux corps composés capables d’absorber la radiation des proches rayons ultraviolets et capables aussi de réagir à l’excitation, à la photo-dégradation, à la photooxydation, etc. Mais il n’y a que peu de cas où l’on ait identifié de façon non-équivoque les photorécepteurs des réactions biologiques observées, et dans pratiquement aucun de ces cas a-t-on suivi de façon sûre la chaîne des réactions menant de l’absorption à la réaction observée. Ces lacunes dans nos informations proviennent, en partie, de notre ignorance du rôle précis des cellules, mais il existe aussi un fossé entre les connaissances acquises par le photochimiste ou le photophysicien et celles du botaniste. Un exemple évident de cet état de choses se trouve dans l’échec général des photobiologistes à définir de façon satisfaisante les limites réelles de leurs expériences. Il est totalement insuffisant de déclarer tout simplement qu’il y a eu une production de proches rayons ultraviolets.Pour terminer d’une façon positive, il nous faut signaler que la photobiologie des plantes est une branche de plus en plus importante dans tous les domaines de la botanique, que les instruments et les techniques de recherche sont aujourd’hui à notre disposition, et que les concepts qui doivent être à la base des recherches sont là.

Primary and secondary causes and consequences of contemporary forest decline

Realization that forest decline (Waldsterben) has become an ecological crisis throughout the developed world has resulted in massive research efforts to determine the causes of declines. It is now recognized that no single causal factor is responsible, but that there are a variety of anthropogenic causal factor complexes interacting with natural events and processes that, together, induce stresses in forests that culminate in declines of individual plants and of ecosystems.It is the thesis of this article that forest declines involve all biotic and abiotic facets and parameters of forested ecosystems and that the declines are themselves new causal factor complexes that continue to affect the stability of forested ecosystems independently of the initial causal factor complexes. Lacking direct field or laboratory studies on these cascades of causes and effects, this article attempts to utilize the growing body of information on plant physiological ecology to provide a heuristic framework for evaluating long-term forest declines.AbstraktDie Erkenntnis, daß das Waldsterben zu einer ökologischen Krise in der gesamten entwickelten Welt geworden ist, hat zu massiven Forschungsanstrengungen nach den Ursachen geführt. Es ist mittlerweile anerkannt, daß nicht ein einzelner verursachender Umstand verantwortlich ist, sondern, daß es sich um eine Vielzahl anthropogener Faktoren im Wechselspiel mit natürlichen Vorgängen handelt; die im Zusammenwirken Stresse in den Wäldern hervorrufen und im Niedergang einzelner Pflanzen oder ganzer Waldökosysteme ihren Ausdruck finden.Dieser Artikel unterstüzt die These, daß das Waldsterben alle biotischen und abiotischen Facetten und Parameter eines Waldökosystems einbezieht und daß die Zerfallsprozesse selbst neue Ursachenkomplexe darstellen, die unabhängig von den ursprünglichen Ursachen, fortgesetzt die Stabilität der Waldökosysteme angreifen. Ohne direkte Feldoder Laboruntersuchungen dieser Kaskaden von Ursache und Wirkung versucht dieser Artikel die ständig wachsende Masse der Information über Pflanzen-ökologie und -physiologie zu nutzen, um ein heuristiches Gitternetz für die Auswertung der Langzeiteffekte des Waldsterbens aufzustellen.

EFFECTS OF GREEN LIGHT ON BIOLOGICAL SYSTEMS

Green light (510–565 nm) constitutes a significant portion of the visible spectrum impinging on biological systems. It plays many different roles in the biochemistry, physiology and structure of plants and animals. In only a relatively small number of responses to green light is the photoreceptor known with certainty or even provisionally and in even fewer systems has the chain of events leading from perception to response been examined experimentally. This review provides a detailed view of those biological systems shown to respond to green light, an evaluation of possible photoreceptors and a review of the known and postulated mechanisms leading to the responses.

RELATIONSHIPS BETWEEN BLUE‐GREEN AND RED ALGAE *

The past decade has seen a revolution in biological thinking comparable in many respects to the period following the publication of Charles Darwin’s Origin o f Species by Means of Natural Selection or the Preservation of Favoured Races in the Struggle f o r Life. We have witnessed and participated in the advent and flowering of molecular genetics, molecular biophysics, and molecular biochemistry, biological disciplines whose impact will continue to influence our teaching and our researches. The concepts that are now part of the present world of biological thought have, as they should and must, provided new orientations and new horizons. Morphology and taxonomy, fields that are basic to our evaluation of life, are actively participating in molecular approaches and their child, evolutionary theory, is more sophisticated as a consequence. Phylogeny, the study of the evolutionary relationships among organisms, is an ugly duckling, by its very nature not susceptible to the experimental method of external verification and interlocking proofs. The operational word in phylogenetic study is “reasonable.” The phylogeneticist hesitates a long time before becoming so rash as to use the word “possible” and “probable” is a word that scarcely passes his lips. Those who speculate on the relationships among plants realize that we are as much philosophers as scientists and although most have Doctor of Philosophy degrees, we tend to be uncomfortable in the role. Although to some, the attempt to separate organisms into taxa, i.e., into hierarchical rankings based on presumed genetic and evolutionary relationships, is a sterile pedantic exercise, I submit that such speculations are reasonable activities and that they have heuristic values in biological thought. As a base for such thinking, the first major task is the ancient one of determining the minimum number of supertaxa needed to include all the organisms that have ever lived. The arguments on this point have centered on the question of whether there should be two, three, four, or more Kingdoms. As we 24 and Allsopp3 have stated, the two-Kingdom approach is favored with the proviso that there be an amorphous grouping of ancient living things that can be termed Archaic. This position is the classical one, a term which has regrettably acquired a pejorative connotation in several recent publications.Il3 2 5 ~ 34 Indeed, the fervor with which the concept of the Kingdom Protista is embraced is surprising in view of its classical history, Ernst Haeckel 21 coined the term in 1866 to include all unicellular organisms not easily seen by the unaided eye. Later developments in optics and laboratory manipulations have resulted in the extension of Haeckel’s operational construct to contain the bacteria (including the Rickettsiales, etc.) , the algae, fungi (including the slime molds), the protozoa and, apparently by

Germination responses of forest tree seed to acidity and metal ions

Abstract Seed germination of red spruce (Picea rubens Sarg.), balsam fir (Abies balsamea L.), yellow birch (Betula alleghaniensis Britt.) and paper birch (Betula papyrifera Marsch) was evaluated under laboratory conditions at pH 3, 4 and 5 with and without phytotoxic metal ions (Al at 10 and 100 mg/l, Cd at 1.0 mg/l, Cu at 5 and 10 mg/l, Pb at 5 and 20 mg/l or Zn at 5 and 10 mg/l). Germination was not reduced by acidity or metals, and there were no significant interactions between acidity and metal concentration in any of the tested species. Balsam fir and yellow birch showed significantly greater germination at pH 3 than at pH 4 or 5. Germination rates were similar among all treatments within a species. This study provides no evidence that acidic, metal-containing soil solutions of high elevation coniferous forest ecosystems suppress seed germination of these species.

Post-irradiation modulation of ionizing radiation damage to plants

Introduction ......................................................................................................... 397 A Brief Consideration of Radiation Theory ..................................................... 398 Division Delay .................................................................................................... 400 Inadequate Growth Media .............................................................................. 401 Temperature-induced Division Delay .............................................................. 401 Chemical Suppression of Division ..................................................................... 402 Ultraviolet Radiations ..................................................................................... 403 Magnetic Fields ........................................................................................... 404 Metabolic Activation .............................................................................................. 404 Intermediary Metabolism ........................................................... : ....................... 404 Nucleic Acid and Protein Synthesis .................................................................. 405 Inorganic Ions ................................................................................................ 407 Plant Growth Regulators ............................................................................... 408 Redox ............................................................................................................... 409 Heat Shock .................................................................................................. 409 Oxidation-reduction Agents ..................................................................... 411 Visible Radiations ........................................................................................... 416 Transmission to Unirradiated Tissues ............................................... 419 General Conclusions .................................................................................. 420 Literature Cited ..................................................................................................... 421

EFFECT OF GROWTH SUBSTANCES ON “APICAL DOMINANCE” IN SPHACELARIA FURCIGERA (PHAEOPHYTA)1

Gibberellic acid (GA), naphthaleneacetic acid (NAA), and kinetin (K) were tested individually and in combinations on the development of filaments of Sphacelaria furcigera Kütz. Unbranched tips from filaments with or without intact apical cells were grown in the presence or absence of growth substances to study their effects on an apical‐dominance‐like response previously observed in this genus. Removal of the apical cell resulted in lateral branches developing significantly closer to the tip than in uninjured controls. GA and K had no effect on location of lateral branches of uninjured filaments, but exerted some control as evidenced by increases in the distance from a punctured apical cell to the nearest lateral branch. NAA had no positive effects and was toxic in even moderate concentrations. The three growth substances in all combinations could not fully replace the apical cell in repressing branch development. GA and K presented simultaneously were no more effective than either presented alone.

Effect of Acidity and Metal Ions on Water Movement Through Red Spruce

Field observations suggested that death of red spruce of all age classes in the northern coniferous forest of Camels Hump Mountain, Vermont could be due in part to inadequate movement of water through the trees. Short term laboratory experiments were conducted with young red spruce to evaluate the possibility that soil solutions and acidic metal ion solutions interfered with water movement. Highly acidic (pH 3.1) spring-collected soil solutions, but not the less acidic (pH 4.5) soil solutions collected in fall, reduced water movement. Aluminum, cadmium and lead ions, at concentrations close to those in spring-collected soil solutions, reduced transpirational water flow. The apparent absence of mycorrhizal associations of red spruce would further limit water uptake and it was found that acidity and metal ions repressed the growth of several species of mycorrhizal fungi.

Effect of borate excess and calcium ion on mitosis of pea root-tip meristem cells

Abstract Meristematic activity of sterile pea ( Pisum sativum L.) root-tips was abolished within 24 hr after presentation of 10 mM borate to the culture medium. Transfer of borate-repressed root-tips showing no mitotic activity to borate-free medium resulted in resumption of mitosis within 2 hr; control-level mitotic activity and normal distribution of mitotic figures were observed within 6 hr; Analysis of studies with tritiated thymidine labeling suggest that borate arrest of mitosis is during G 2 . Calcium ion reversed the borate repression of mitotic activity.

Techniques for pollution monitoring in remote sites: I. Near real-time rainfall pH and depth

A flow-through system for in situ, near real-time, sequential measurements of rainfall pH and depth was developed for monitoring of precipitation in sites lacking electric power. The system is easily fabricated from readily available instruments and materials, portable, relatively inexpensive and requires minimal maintenance. It also operates independently of AC power making it ideal for use in remote areas. Initial field testing of this system on Camels Hump, Vermont, took place over the period of July to August 1990, during which twenty-seven individual storm events were monitored. The system proved to be robust and reliable, providing rainfall pH and depth information with high (programmable) temporal resolution for unattended periods of up to a week.