Rehydration of Phytochrome in Imbibing Seeds of Amaranthus retroflexus L.
نویسندگان
چکیده
It is commonly recognized that light-sensitive seeds require a period of imbibition before full promotion of germination by a light stimulus can be attained. Yet little work describes the nature of these preliminary events. Of the several major limitations that may be involved, clearly the rehydration (or activation) of phytochrome and the system with which it interacts are the chief ones to consider. The object of this communication is to describe the rehydration of inactive phytochrome (Pr) in Amaranthus retroflexus L. seeds as determined by a method by which phytochrome rehydration can be physiologically separated from other events occurring during dark imbibition. Recently, Tobin and Briggs (1 1) presented evidence for rapid rehydration of phytochrome in isolated embryos of Pinus palustris Mill. Using spectrophotometric methods, they detected low levels of phytochrome in dry seeds and much larger amounts 2 min after the addition of water. However, physiological changes in germination connected with the phytochrome system were not displayed until seeds had imbibed for approximately 3 hr. Nyman (6) found that irradiation of dry seeds of Pinus sylvestris L. with red light could give subsequent promotion of germination. Recent studies by several authors using spectrophotometry traced the appearance and increase of phytochrome levels in various seeds (1, 4, 5, 7, 8). Some found phytochrome only in imbibed seeds (4, 5), while others could detect the pigment in dry seeds as well (1, 8). Kendrick et al. (4) found that water uptake of Amaranthus caudatus L. seeds followed the same pattern as the initial increases in phytochrome, but McArthur and Briggs (5) presented evidence that appearance of phytochrome in peas was not strictly correlated with water uptake. Most of these reports do not attempt to associate the early appearance of phytochrome in imbibing seeds with any physiological role. In a previous paper (9), we presented some evidence that rehydration of the inactive and active (Pfr) forms of phytochrome could be detected physiologically during prechilling of A. retroflexus seeds. This paper supports and extends these findings.
منابع مشابه
Action of Phytochrome During Prechilling of Amaranthus retroflexus L. Seeds.
Dark germination of Amaranthus retroflexus L. seeds at 35 degrees increased after several days of prechilling at 20 degrees or lower. Irradiation with far-red light for short periods during the early hours of a prechilling period at 10 degrees inhibited subsequent dark germination at 35 degrees . The inhibition was completely reversible with red light. Far-red irradiation in the latter part of ...
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Effects of red (600 to 680 nanometers) and far red (700 to 760 nanometers) irradiances on Amaranthus retroflexus L. seeds indicate that synthesis of phytochrome in the red-absorbing form takes place in water-imbibed nongerminating seeds at 35 C. After 96 hours in darkness, conversion of about 0.10% phytochrome to the far red-absorbing form induces 50% germination. Continuous far red radiation a...
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Background: The use of allelopathic plant extracts as herbicide is being popularized in recent years. Objective: This research has been conducted to evaluate the allelopathic potential of caltrop (Tribulus terrestris L.) on seed germination and growth of Avena fatua L., Chenopodium album L., Setaria viridis L. and Amaranthus retroflexus L. Methods: This research was done to evalature the ef...
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ورودعنوان ژورنال:
- Plant physiology
دوره 49 4 شماره
صفحات -
تاریخ انتشار 1972