Blue Light Interference in the Phytochrome-controlled Germination of the Spores of <i>Cheilanthes farinosa</i>

Raghavan, V.

doi:10.1104/pp.51.2.306

Cited by 21 publications

(10 citation statements)

References 21 publications

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“…Environmental regulation of seed germination in both monocots and dicots is controlled in part by a phytochrome-mediated reversible system, with red (R) light promoting germination, and even brief exposure to far-red (FR) light inhibiting R lightinduced germination (Borthwick et al, 1952;Shinomura et al, 1994;Hennig et al, 2002), although this trait has been bred out of some commercial cereal crops (Barrero et al, 2012). A similar R-FR reversible system regulates spore germination in several ferns (Mohr et al, 1964;Raghavan, 1973;Wayne & Hepler, 1984;Scheuerlein et al, 1989;Tsuboi et al, 2012). In the earliest-evolving land plant lineage, bryophytes, complete inhibition of spore germination by FR light, and reversal of this inhibition by R light via phytochromes, has been demonstrated (Possart & Hiltbrunner, 2013).…”

Section: Introductionmentioning

confidence: 99%

The decision to germinate is regulated by divergent molecular networks in spores and seeds

et al. 2016

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Summary Dispersal is a key step in land plant life cycles, usually via formation of spores or seeds. Regulation of spore‐ or seed‐germination allows control over the timing of transition from one generation to the next, enabling plant dispersal. A combination of environmental and genetic factors determines when seed germination occurs. Endogenous hormones mediate this decision in response to the environment. Less is known about how spore germination is controlled in earlier‐evolving nonseed plants.Here, we present an in‐depth analysis of the environmental and hormonal regulation of spore germination in the model bryophyte Physcomitrella patens (Aphanoregma patens).Our data suggest that the environmental signals regulating germination are conserved, but also that downstream hormone integration pathways mediating these responses in seeds were acquired after the evolution of the bryophyte lineage. Moreover, the role of abscisic acid and diterpenes (gibberellins) in germination assumed much greater importance as land plant evolution progressed.We conclude that the endogenous hormone signalling networks mediating germination in response to the environment may have evolved independently in spores and seeds. This paves the way for future research about how the mechanisms of plant dispersal on land evolved.

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Section: Introductionmentioning

confidence: 99%

The decision to germinate is regulated by divergent molecular networks in spores and seeds

et al. 2016

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“…Necessary manipulations in the dark were carried out under dim green light (14). The standard incubation temperature was 25 C. Incubators (Precision Instruments) were used to obtain other incubation temperatures (5,10,15,20,30,35,38,40,43, and 50 C). Incubator temperatures were maintained within 1 C fluctuations.…”

Section: Methodsmentioning

confidence: 99%

“…However, spores incubated at 25 C require light for maximal induction of germination (5,14). Spore germination of many fern species, including Onoclea, is apparently controlled by phytochrome (6)(7)(8)(9)(10)(11)(12).…”

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Photocontrol of the Germination of Onoclea Spores

Chen

Ikuma²

1979

Plant Physiol.

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The physiological nature of photoinduced germination of Onoclea sensibilis L. spores was investigated by temporarily applying a range of temperatures, particularly 40 C, before and after short light treatment. Controls were germinated at 25 C.The preinduction phase, during which photosensitivity is maximally developed in the dark, is sensitive to temperature. Treatment at 40 C for 8 or more hours reduces the developed photosensitivity to a minimal level, but the inhibition by 40 C treatment is reversed slowly after subsequent incubation at 25 C in the dark. The postinduction phase, in which dark processes lead to stain uptake and eventually to visible protrusion, is also sensitive to temperature. Inhibition by 40 C occurs shortly after photoinduction, but disappears 6 or more hours after irradiation. Postinduction spores whose germination is inhibited by 40 C treatment recover the ability to germinate after subsequent incubation at 25 C plus a second light treatment. The inhibition and recovery take place faster in postinduction spores than in preinduction spores. In addition, escape from 40 C inhibition is found in the postinduction phase but not in the preinduction phase. Temperatures lower than 25 C exert slow inhibition of both pre-and postinduction processes, and 30 to 35 C act to stimulate germination.In comparison with our earlier work with anaerobiosis and cycloheximide, the postinduction step inhibited by 40 C can be located shortly after the step inhibited by anaerobiosis but before the cycloheximide sensitive step.Onoclea spores germinate optimally in both light and darkness at an incubation temperature of 28 to 30 C, while incubation at 40 C is lethal to the spores (5, 12, 13). If a temporary treatment at 30 C is started within the first 12 h of dark soaking at 25 C, dark germination of Onoclea spores is maximal (12, 13). However, spores incubated at 25 C require light for maximal induction of germination (5,14). Spore germination of many fern species, including Onoclea, is apparently controlled by phytochrome (6-12).The germination processes of Onoclea spores have been operationally divided into the following three sequential phases with respect to short light treatment (15, 16): (a) a preinduction phase in which the spores imbibe water and develop maximal photosensitivity in the dark; (b) a photoinduction phase when light induces germination maximally; and (c) a dark postinduction phase in which photoinduced processes lead to unequal cell division and eventually to visible protrusion of rhizoidal and protonematal cells. The photoinduction phase is independent of temperature and anaerobiosis (15), but the two dark phases involve processes ' To whom request for reprints should be addressed.sensitive to anaerobiosis (15), cycloheximide (16), ethylene (2-4), and probably CO2 (1). The physiological nature of the two dark phases was further investigated by treating spores at various temperatures, particularly at an elevated temperature of 40 C. MATERIALS AND METHODSThe spores of Onoclea sensibil...

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“…Red light was ohtained hy filtering light from two 15-W fluorescent tubes through a 3 mm thick red Piexiglas (Rohm and Haas, No. 2444) (Raghavan, 1973). Photo-induced spores were held in complete darkness for 6 days before scoring for germination and growth of protonemata.…”

Section: Methodsmentioning

confidence: 99%

ABSCISIC ACID EFFECTS ON SPORE GERMINATION AND PROTONEMAL GROWTH IN THE FERN, MOHRIA CAFFRORUM

Chia

Raghavan

1982

New Phytologist

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SUMMARYThe effects of abscisic acid (ABA) and its interaction with gibbereOic acid (GA), indoleacetic acid (IAA) and kinetin on the germination of spores and growth of protonemata of the fern, Mohria caffrorum Sw. -were studied. ABA did not affect the initial divisions of the spore protoplast leading to the formation of rhizoid and protonenna, but inhibited the subsequent elongation of the latter. The apparent reversal of ABA-induced inhibition of protonemal elongation by GA appears to be due to an overall growth promotion by GA,. rather than due to its interaction -with ABA. On the other hand, both IAA and kinetin, which by themselves did not promote protonemal gro-wth, reversed to some extent the inhibitory effect of ABA on the growth of the protoneniia.

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Blue Light Interference in the Phytochrome-controlled Germination of the Spores of Cheilanthes farinosa

Cited by 21 publications

References 21 publications

The decision to germinate is regulated by divergent molecular networks in spores and seeds

The decision to germinate is regulated by divergent molecular networks in spores and seeds

Photocontrol of the Germination of Onoclea Spores

ABSCISIC ACID EFFECTS ON SPORE GERMINATION AND PROTONEMAL GROWTH IN THE FERN, MOHRIA CAFFRORUM

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