Developmental arrest: from sea urchins to seeds

Abstract

The phenomenon of dormancy extends beyond the boundaries of the plant kingdom. While plant biologists typically associate dormancy-breaking treatments only with seeds, buds or tubers, these chemicals and environmental stimuli have much broader activity as general terminators of developmental arrest in other, non-plant species. The activation of growth by these treatments is associated with signal transduction processes, metabolic upregulation and changes in gene expression, in addition to other events that may or may not be species specific. The study of both the classic and current developmental arrest literature beyond the boundaries of plant biology may be helpful in generating useful ideas and analogies for meaningful experimental progress towards understanding seed dormancy. Breaking dormancy of Avena fatua L. seed by treatment with ammonia. Weed Research 26, 191-197. Charbonneau, M. and Grandin, N. (1989) The egg of Xenopus laevis: a model system for studying cell activation. Cell Differentiation and Development 28, 71-94. Clark, J.F. (1898) Electrolytic dissociation and toxic effect. The metabolic status of diapause embryos of Artemia franciscana (SFB). Physiological Zoology 69, 49-66. Cohn, M.A. (1987) Mechanisms of physiological seed dormancy. pp. 14-20 in Frasier, G.W.; Evans, R.A. (Eds) Seed and seedbed ecology of rangeland plants. Washington DC, USDA-ARS. Cohn, M.A. (1989) Factors influencing the efficacy of dormancy-breaking chemicals. pp. 261-267 in Taylorson, R.B. (Ed.) Recent advances in the development and germination of seeds. New York, Plenum Press. Cohn, M.A. (1996a) Chemical mechanisms of breaking seed dormancy. Seed Science Research 6, 95-99. Cohn, M.A. (1996b) Operational and philosophical decisions in seed dormancy research. Seed Science Research 6, 147-153. Cohn M.A. (1997) QSAR modelling of dormancy-breaking chemicals. pp. 289-295 in Ellis, R.H.; Black, M.; Murdoch, A.J.; Hong, T.D. (Eds) Basic and applied aspects of seed biology. Dordrecht, Kluewer Academic. Cohn, M.A. and Castle, L. (1984) Dormancy in red rice. IV. Response of unimbibed and imbibing seeds to nitrogen dioxide. Physiologia Plantarum 60, 552-556. Cohn, M.A. and Footitt, S. (1993) Initial signal transduction steps during the dormancy-breaking process. pp. 599-605 in Côme, D.; Corbineau, F. (Eds) Proceedings of the fourth international workshop on seeds: basic and applied aspects of seed biology. Volume 2. Paris, ASFIS. Cohn, M.A. and Hilhorst, H.W.M. (2000) Alcohols that break seed dormancy: The anaesthetic hypothesis, dead or alive? pp. 259-274 in Viémont, J.-D.; Crabbé, J. (Eds) Dormancy in plants. From whole plant behaviour to cellular control. Wallingford, CABI Publishing. Cohn, M.A. and Hughes, J.A. (1986) Seed dormancy in red rice. V. Response to azide, hydroxylamine, and cyanide. Plant Physiology 80, 531-533. Cohn, M.A., Butera, D.L. and Hughes, J.A. (1983) Seed dormancy in red rice. III. Response to nitrite, nitrate, and ammonium ions. Plant Physiology 73, 381-384. Cohn, M.A., Chiles, L.A., Hughes, J.A. and Boullio...

Pollenkitt – its composition, forms and functions

“…Why is this high-energy fluid used as glue? A reason may be because pollen is often dispersed in an arrested developmental state, usually by means of partial dehydration (Franchi et al, 2002;Fotitt and Cohn, 2001). Coating pollen with a semipermeable fluid is a way to reduce water loss and uptake, especially during long presentation and dispersal.…”

Burning vegetation produces cyanohydrins that liberate cyanide and stimulate seed germination

“…Spontaneous decomposition of the cyanohydrin or enzymatic catalysis by an α-hydroxynitrile lyase can yield hydrogen cyanide and an aldehyde or a ketone 25 . Hydrogen cyanide or solutions of cyanide can stimulate the germination of seeds of different plant species [26][27][28][29][30] and different aldehydes and ketones can also promote seed germination 31 . The dormancy-breaking effect of cyanides can be elicited by continuous contact at low doses or by short exposure times (ca.…”

Pollen vacuoles and their significance

“…In Pteridophyta, such as Matteuccia and Equisetum, ripe spores contain vacuoles; in others such as Polypodium vulgare vacuoles are absent and water content is around 5% (Cran 1979). In other terrestrial plants, vacuoles are reduced in meristems and practically absent in ripe pollen and seeds, namely in reproductive structures dispersed with a low water content in an arrested developmental state (Heslop-Harrison 1979;Footitt and Cohn 2001). Nevertheless vacuoles are present in seed and pollen at various stages of development as well as during their germination (Heslop-Harrison 1987;Hicks et al 2004).…”