The Effect of Sucrose on Apogamy in Cyrtomium falcatum Presl

Whittier, P.

doi:10.2307/1547093

Cited by 23 publications

(8 citation statements)

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“…Many studies have examined the biotic and abiotic forces shaping apogamy in ferns (see Sheffield and Bell, 1987). Together, this body of work illustrates that exposure to light is a key trigger for inducing apogamy and that exogenous sugars (especially sucrose) are a critical metabolic requirement that also shape osmotic potential for the developing apogamous sporophytes (Bell, 1959; Whittier and Steeves, 1960, 1962; Bristow, 1962; Whittier, 1964a, 1974, 1976; Whittier and Pratt, 1971; Elmore and Whittier, 1975; Padhya and Mehta, 1981; Cordle et al, 2007). Experimental studies have demonstrated that exposure to light or to sugar, alone, is insufficient to induce apogamy (Whittier and Steeves, 1960, 1962; Whittier, 1974, 1975; Padhya and Mehta, 1981).…”

Section: A Model For the Establishment Of Obligate Apomixis In Fernsmentioning

confidence: 95%

“…Facultative apogamy usually involves the production of (sometimes numerous) sporophytic (2 n ) buds that arise late in gametophyte development. Such budding gametophytes are generally large and irregular (Duncan, 1943; Whittier, 1964a, b), with apogamous sporophytes distributed haphazardly across the prothallium (Farlow, 1894; Debenedictis, 1969; Whittier, 1974; Elmore and Whittier, 1975; Gabancho et al, 2010). In cases of obligate apogamy, however, the sporophyte arises earlier in development from a well‐defined area of the gametophyte cushion (usually immediately behind the apical notch), and at roughly the same timepoint that archegonia would appear in sexual prothalli (Duncan, 1943; Debenedictis, 1969).…”

Section: A Model For the Establishment Of Obligate Apomixis In Fernsmentioning

confidence: 99%

“…These modifications—whose coordination might span ca.100–200 years, from one generation to the next—appear to be driven by environmental conditions. Available evidence suggests that there are tangible associations between obligate apomixis and a plurality of abiotic factors, including temperature, substrate composition, and water availability (e.g., Bell, 1959; Whittier, 1964a, b; Hickok, 1977b; Padhya and Mehra, 1981).…”

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A drought‐driven model for the evolution of obligate apomixis in ferns: evidence from pellaeids (Pteridaceae)

Grusz

Windham

Picard

et al. 2021

American J of Botany

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Premise Xeric environments impose major constraints on the fern life cycle, yet many lineages overcome these limitations by evolving apomixis. Here, we synthesize studies of apomixis in ferns and present an evidence‐based model for the evolution and establishment of this reproductive strategy, focusing on genetic and environmental factors associated with its two defining traits: the production of “unreduced” spores (n = 2n) and the initiation of sporophytes from gametophyte tissue (i.e., diplospory and apogamy, respectively). Methods We evaluated existing literature in light of the hypothesis that abiotic characteristics of desert environments (e.g., extreme diurnal temperature fluctuations, high light intensity, and water limitation) drive the evolution of obligate apomixis. Pellaeid ferns (Cheilanthoideae: Pteridaceae) were examined in detail, as an illustrative example. We reconstructed a plastid (rbcL, trnG–trnR, atpA) phylogeny for the clade and mapped reproductive mode (sexual versus apomictic) and ploidy across the resulting tree. Results Our six‐stage model for the evolution of obligate apomixis in ferns emphasizes the role played by drought and associated abiotic conditions in the establishment of this reproductive approach. Furthermore, our updated phylogeny of pellaeid ferns reveals repeated origins of obligate apomixis and shows an increase in the frequency of apomixis, and rarity of sexual reproduction, among taxa inhabiting increasingly dry North American deserts. Conclusions Our findings reinforce aspects of other evolutionary, physiological, developmental, and omics‐based studies, indicating a strong association between abiotic factors and the establishment of obligate apomixis in ferns. Water limitation, in particular, appears critical to establishment of this reproductive mode.

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Section: A Model For the Establishment Of Obligate Apomixis In Fernsmentioning

confidence: 95%

Section: A Model For the Establishment Of Obligate Apomixis In Fernsmentioning

confidence: 99%

mentioning

confidence: 99%

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A drought‐driven model for the evolution of obligate apomixis in ferns: evidence from pellaeids (Pteridaceae)

Grusz

Windham

Picard

et al. 2021

American J of Botany

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“…To reduce the incidence of contamination, the spores were wetted and stored in water for 24 h before surface sterilization. They were then surface sterilized with 20% Clorox (1.1% sodium hypochlorite) using the method of Whittier (1964). Under sterile conditions, the spores were rinsed with water, collected on filter paper, suspended in water and sown on 13 mL of nutrient medium in culture tubes (20 mm Â 125 mm) with screw caps that were tightened to reduce moisture loss.…”

Section: Methodsmentioning

confidence: 99%

Red light inhibition of spore germination in Ophioglossum crotalophoroides

Whittier

2006

Can. J. Bot.

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Spores of Ophioglossum crotalophoroides Walt., which give rise to subterranean, nonphotosynthetic, mycorrhizal gametophytes, germinate in the dark and not in the light. Red light, like white light, prevents the germination of these spores. Germination occurs after exposure to far-red. The effects of far-red light can be reversed by red light and those of red light can be partly reversed by far-red light, confirming the involvement of phytochrome. With the spores of O. crotalophoroides, the active form of phytochrome, Pfr, prohibits germination. The photoinhibition of germination by white or red light insures that these spores germinate underground in nature. Hypogean germination improves the chances for adequate soil moisture and for the young gametophytes to be colonized by mycorrhizal fungi.Résumé : Les spores de l'Ophioglossum crotalophoroides Walt., qui forment un gamétophyte souterrain, non-photosynthé-tique et mycorhizien, germent à la noirceur et non à la lumière. La lumière rouge, tout comme la lumière blanche, prévient la germination des spores. La germination a lieu après une exposition à la lumière rouge sombre. On peut renverser les effets de la lumière rouge sombre par la lumière rouge, et ceux de la lumière rouge peuvent être partiellement renversé par la lumière rouge sombre, ce qui confirme l'implication du phytochrome. Chez les spores de l'O. crotalophoroides la forme active Pfr du phytochrome, empêche la germination. La photoinhibition de la germination par la lumière blanche ou rouge assure que la germination de ces spores s'effectue dans le sol, en nature. La germination hypogée augmente les chances de rencontrer une humidité convenable du sol et que le jeune gamétophyte soit colonisé par des champignons mycorhiziens.

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“…The spores were sown within one month of their collection. To redtice the incidence of contamination, the spores were wetted and stored in water for 24 hours and surface sterilized with 20% Clorox (1.1% sodium hypochlorite) by the method of Whittier (1964). The spores were then suspended in sterile water, and sown on 13 ml of nutrient medium in culture tubes (20 X 125 mm) with screw caps that were then tightened.…”

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confidence: 99%

The Gametophyte of Huperzia selago in Culture

Whittier

Štorchová

2007

American Fern Journal

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Cultured gametophytes of Huperzia selago are dorsiventral and strap-shaped. They are basically the same as cultured gametophytes of other terrestrial Huperzia species and also essentially the same as gametophytes of H. selago collected from loose soil. Besides shape, the cultured gametophytes have anatomical features found in gametophytes of H. selago from loose soil. These gametophytes are Type III gametophytes as characterized by Bruchmann in 1898. Although both gametangia occur on individual cultured gametophytes, the meristematic groove produces them at different times and they are not intermixed. The number of terrestrial Huperzia species with described gametophytes is still small (six), but that number has tripled as a result of the recent studies on these gametophytes in culture. Because all the terrestrial Huperzia species to date have Type III gametophytes, it would not be unexpected for the undescribed gametophytes of other species in this group to also be Type III gametophytes.

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The Effect of Sucrose on Apogamy in Cyrtomium falcatum Presl

Cited by 23 publications

References 0 publications

A drought‐driven model for the evolution of obligate apomixis in ferns: evidence from pellaeids (Pteridaceae)

A drought‐driven model for the evolution of obligate apomixis in ferns: evidence from pellaeids (Pteridaceae)

Red light inhibition of spore germination in Ophioglossum crotalophoroides

The Gametophyte of Huperzia selago in Culture

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