Chemical mechanisms of breaking seed dormancy

Cohn, Marc Alan

doi:10.1017/s0960258500003111

Cited by 19 publications

(12 citation statements)

References 28 publications

(23 reference statements)

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“…This means that determination of relevant parameters should take place before visible sprouting, but even then it is hard to identify the parameters as dormancy breaking parameters or sprouting parameters. Discussing dormancy of true seeds, Cohn (1996) stated: 'if one desires to increase the chances of successfully identifying events associated with the dormancy breaking process, it is essential to conduct time course studies using chemical pulse treatments applied to a uniform and vigorous seed sample'. Markers for the progression from dormancy to germination processes, i.e.…”

Section: Dormancy Breaking and Sproutingmentioning

confidence: 99%

Is dormancy breaking of potato tubers the reverse of tuber initiation?

Claassens

Vreugdenhil

2000

Potato Res

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SummaryTuber formation is a well orchestrated physiological event that involves many metabolic changes. Dormancy gradually develops in potato tubers from the moment cell division in the stolon tip has stopped and the tuber starts to develop. Dormancy breakage may be the reverse of dormancy initiation suggesting that there may be similarities between tuber induction and dormancy development.Based on a literature review it is concluded that, when comparing tuber induction and the breaking of dormancy, hormonal activities are only partly reversed, whereas carbohydrates and enzyme activities might be reversed.For more definite conclusions more research should be done to assess precisely the moment of dormancy breaking. Moreover. measurements on events associated with tuber induction and dormancy breaking should be carried out using the same techniques and the same material.Molecular genetic analyses may provide well-defined markers for the timing of breaking of dormancy.

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Section: Dormancy Breaking and Sproutingmentioning

confidence: 99%

Is dormancy breaking of potato tubers the reverse of tuber initiation?

Claassens

Vreugdenhil

2000

Potato Res

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“…Another disadvantage of the pharmacological approach is that the biochemical response measured may be specific to the chemical challenge rather than a controlling response involved in the dormancybreaking process. Our research (reviewed in Cohn, 1996) has shown that dormancy-breaking chemicals that are closely related structurally may elicit very different metabolic reactions from the seed. Therefore, my own approach in using dormancy-breaking chemicals is to employ a comparative strategy as a control.…”

Section: Choosing Environmental or Chemical Probes To Perturb The Dormentioning

confidence: 99%

Operational and philosophical decisions in seed dormancy research

Cohn

1996

Seed Sci. Res.

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Many research questions focused upon seed dormancy and germination remain unanswered due to problems created by inappropriate assumptions concerning the design and implementation of experiments. Lack of attention to the genetic background and growing conditions required for seed production and subsequent storage may compromise an investigator's ability to pool data or assimilate data trends due to variability in seed performance from year to year. Seed aging events during the afterripening process can be mistaken for those involved in the transition from the dormant to nondormant state. After imbibition, inaccurate criteria for and scoring of the germination event may lead to confusion of seed vs. seedling physiology and biochemistry. In addition, a sufficient number and proper spacing of data points during timecourse experiments are required to properly stage a sequence of events. Studies comparing dormant vs. nondormant seeds must be supplemented with kinetic experiments examining the effect of a dormancy-breaking treatment upon the transition between the dormant and nondormant states. In comparisons of the relative efficacy of various dormancy-breaking chemical treatments, the physical properties of substances under evaluation (e.g. lipophilicity) should be considered. In addition, since many dormancy-breaking chemicals are toxic to vegetative growth, there is a danger of introducing pharmacological artifacts that confuse interpretation of the results obtained. These toxic properties also necessitate the use of viability tests during construction of dose-response curves to avoid confusing seed death with dormancy. Seed scientists must also avail themselves of the extensive literature on developmental arrest in other organisms, which may generate fresh ideas for experimentation.

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“…However, GA application is not the only way to break dormancy experimentally. Many abiotic factors may suffice, such as anaerobiosis, freezing, high temperature, and a range of different chemicals (Cohn, 1996; Rinne et al ., 1997; Shirazi and Fuchigami, 1995; Tanino et al ., 1989; Wisniewski et al ., 1996). The fact that such a wide variety of factors can break dormancy brings into question the existence of universal key components and pathways in dormancy cycling, as well as the validity of existing theories and concepts (Lang, 1987).…”

Section: Introductionmentioning

confidence: 99%

The shoot apical meristem restores its symplasmic organization during chilling‐induced release from dormancy

2001

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SummaryThe shoot apex of overwintering perennials ceases its morphogenetic activity at the end of the growing season and transforms into a bud which is dormant and freezing-tolerant. In birch (Betula pubescens) these events are triggered by short photoperiod, and involve the production of 1,3-b-D-glucan containing sphincters on the plasmodesmata. As a result, all symplasmic pathways shut down. Here we show that breakage of bud dormancy by chilling involves restoration of the symplasmic organization of the meristem. This restoration is likely to be mediated by 1,3-b-D-glucanase, which was present in small spherosome-like vacuoles that arose de novo during dormancy induction. During chilling these vacuoles were displaced from the bulk cytoplasm to the cortical cytoplasm where they became aligned with the plasma membrane, often associated with plasmodesmata. At this stage the enzyme also appeared outside the vacuoles. During chilling, 1,3-b-D-glucan disappeared from the plasmodesmal channels and wall sleeves, and the plasmodesmata regained the capacity for cell±cell transport, as demonstrated by microinjection of Lucifer Yellow CH and Fluorescein-tagged gibberellic acid. Collectively, the present experiments demonstrate that restoration of the symplasmic organization of the meristem is indispensable for the release of buds from dormancy and the assumption of a proliferation-competent state, and implicate 1,3-b-D-glucanase action at the plasmodesmata. Based on these ®ndings we propose a model for`dormancy cycling' which depicts the meristem as passing through three sequential states of cellular communication with characteristic sensitivities to distinct environmental cues.

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Chemical mechanisms of breaking seed dormancy

Cited by 19 publications

References 28 publications

Is dormancy breaking of potato tubers the reverse of tuber initiation?

Is dormancy breaking of potato tubers the reverse of tuber initiation?

Operational and philosophical decisions in seed dormancy research

The shoot apical meristem restores its symplasmic organization during chilling‐induced release from dormancy

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