Ultrastructural and Photosynthetic Features of Leaves and Stems of Elodea canadensis

Rascio, Nicoletta; Mariani, Paola; Vecchia, Francesca Dalla; Zanchin, A.; Pool, Alison; Larcher, Walter

doi:10.1016/s0176-1617(11)81193-4

Cited by 26 publications

(10 citation statements)

References 25 publications

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“…A reserva de amido foi significativamente maior na planta submersa de B. salzmanii, concordando com as observações feitas por Fahn (1990), Hostrup & Wiegleb (1991) e Rascio et al (1994). Segundo Brändle & Crawford (1987), o acúmulo de amido é uma adaptação metabólica para hipoxia, que garante adequada reserva de carbono para caso de aumento da demanda.…”

Section: Discussionunclassified

Anatomia das raízes de Bacopa salzmanii (Benth.) Wettst. Ex Edwall e Bacopa Monnierioides (Cham.) Robinson (Scrophulariaceae) em ambientes aquático e terrestre

Bona

Morretes

2003

Acta Bot. Bras.

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Bonito e no Pantanal do Mato Grosso do Sul. As análises foram feitas do ápice à base da raiz, enfatizando a origem e desenvolvimento dos tecidos. O meristema apical apresenta a mesma estrutura nas duas espécies e não sofre alterações marcantes com a mudança do ambiente. Todos os tecidos se originam de três camadas distintas, na região do promeristema. A endoderme jovem é meristemática e dá origem ao córtex. O aerênquima é abundante e os septos podem conter espessamento em fi. A exoderme é unisseriada e composta por células curtas e longas. A coifa das duas espécies é pouco desenvolvida e apresenta estrutura semelhante nos dois ambientes.Palavras-chave -Bacopa sp., anatomia da raiz, aerênquima, planta aquática ABSTRACT -(Anatomy of roots of Bacopa salzmanii (Benth.) Wettst. Ex Edwall and B. monnierioides (Cham.) Robinson (Scrophulariaceae) in aquatic and terrestrial environments). This work describes the anatomy of roots of Bacopa salzmanii (Benth.) Wettst. Ex Edwall and B. monnierioides (Cham.) Robinson and its adaptations to aquatic and terrestrial environments. Both species were collected in the city of Bonito and in the Pantanal (State of Mato Grosso do Sul). Adventitious roots were analyzed, from the apex to the base of the root. Tissues origin and development were emphasized. The apical meristem presents the same structure in both species and it is not significantly altered by the environmental changes. All the tissues are originated from three different layers, in the region of the promeristem. The young endodermis is meristematic and originates the cortex. The aerenchyma is abundant and the septa may contain phi thickenings. The exodermis is uniserial and composed of short and elongated cells. Root cap of both species is few developed in both environments.

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Section: Discussionunclassified

Anatomia das raízes de Bacopa salzmanii (Benth.) Wettst. Ex Edwall e Bacopa Monnierioides (Cham.) Robinson (Scrophulariaceae) em ambientes aquático e terrestre

Bona

Morretes

2003

Acta Bot. Bras.

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“…The higher surface-to-volume ratios of submerged leaves as compared to leaves exposed to air reflects the limitations to diffusion of CO2 in water as compared to that in air and the absorption of inorganic carbon through the epidermis (Nobel and Walker 1985). In the epidermis of leaves of submerged aquatic plants, ingrowth of the cell walls and chloroplasts are often observed (Sculthorpe 1967;Gunning and Pate 1969;Valanne et al 1982;Rascio et al 1994). However, such features were never observed in the epidermis of the submerged form of E. vivipara.…”

Section: Discussionmentioning

confidence: 99%

Structural characterization of photosynthetic cells in an amphibious sedge, Eleocharis vivipara, in relation to C3 and C4 metabolism

Ueno

1996

Planta

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Abstract.Eleocharis vivipara Link is a unique amphibious leafless sedge. The terrestrial form has Kranz anatomy and the biochemical traits of C4 plants while the submerged form develops structural and biochemical traits similar to those of C3 plants. The structural features of the culms, which are the photosynthetic organs, of the two forms were examined and compared. The culms of the terrestrial form have mesophyll cells and three bundle sheaths which consist of three kinds of cell, namely, the innermost Kranz cells that contain large numbers of organelles, the middle mestome sheath cells that lack chloroplasts, and the outermost parenchyma sheath cells that contain chloroplasts. The culms of the submerged form had a tendency towards reduction in numbers and size of Kranz cells and vascular bundles, as compared to the terrestrial form, and they had spherical mesophyll cells that were tightly packed without intercellular spaces inside the epidermis. The submerged form had a higher ratio of cross-sectional area of mesophyll cells plus parenchyma sheath cells to that of Kranz cells than the terrestrial form. The difference was mainly due to a decrease in the number and the size of the Kranz cells and to a marked increase in the size of the mesophyll cells and the parenchyma sheath cells in the submerged form, as compared to the terrestrial form. The Kranz cells of the terrestrial form had basically the structural characteristics of plants of the NAD-malic enzyme type, with the exception of the intracellular location of organelles. The Kranz cells of the submerged form included only a few organelles, and the percentage of organelles partitioned to the Kranz cells was significantly smaller in the submerged form than in the terrestrial form. In addition, the size of chloroplasts of the Kranz cells was 60-70% of that of the terrestrial form. These structural differences between the two forms may be related to the functional differences in their mechanisms of photosynthesis.Abbreviations: KC = Kranz cell; MC = mesophyll cell; PSC = parenchyma sheath cell; NAD-ME = NAD-malic enzyme; VB = vascular bundle

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“…The specific distribution among organs of macrophytes sometimes allows assumptions on the mechanisms of accumulation of some metals and their roles in plant metabolism [6]. Photoassimilating organs (leaves and shoots) account for the largest part of Elodea phytomass and are characterized by substantial ultrastructural and physiological differences [8], which may affect the intensity of 241 Am accumulation in them. The distribution of americium-241 and other transuranium elements in organs of Elodea had not been studied before.…”

mentioning

confidence: 99%

“…Thus, the leaf biomass had a twofold greater capacity for accumulating americium than the stem biomass had. Probably, the obtained data may be accounted for by physiological differences between the two plant organs and ultrastructural differences between their tissues [8].…”

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confidence: 99%

New Data on the Accumulation of Americium-241 by Photoassimilation Organs of the Aquatic Plant Elodea canadensis

Зотина

Bondareva

2005

Dokl Biol Sci

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The Yenisei River is polluted with transuranium elements because of operation of the Mining-and-Chemical Combine of the Ministry of Atomic Energy of the Russian Federation (Zheleznogorsk) [1,2]. One of them is 241 Am [3]. Observations in the waters of the Chernobyl zone contaminated with radioactive fallout demonstrated that aquatic plants accumulate 241 Am in their biomass in a species-specific manner [4]. Our experiments showed that Elodea ( Elodea canadensis ), a submerged aquatic plant belonging to the phytocenosis of the Yenisei River, can accumulate considerable 241 Am radioactivity [5]. The mechanism of americium accumulation by aquatic plants is still unknown. Studies on the accumulation of heavy metals and radionuclides showed substantial differences in their contents between different organs of aquatic plants [6,7]. The specific distribution among organs of macrophytes sometimes allows assumptions on the mechanisms of accumulation of some metals and their roles in plant metabolism [6]. Photoassimilating organs (leaves and shoots) account for the largest part of Elodea phytomass and are characterized by substantial ultrastructural and physiological differences [8], which may affect the intensity of 241 Am accumulation in them. The distribution of americium-241 and other transuranium elements in organs of Elodea had not been studied before.Therefore, we analyzed the characteristics of 241 Am accumulation by the leaves and stems of E. canadensis , a submerged aquatic plant.The shoots of Elodea were used for laboratory experiments. Elodea is a common component of phytocenoses throughout the Yenisei and most bodies of water in the Northern Hemisphere [6,9]. The plants were collected in the Yenisei upstream of the radioactive contamination zone in late July 2004. We used unbranched shoots with apices. The shoots were washed with tap water and exposed in glass cylinders filled with water from the Yenisei (0.7 l per cylinder) filtered through Vladipor membranes with a mesh size of 1 µ m. We used a total of 28 shoots 12-22 cm in length. The cylinders were illuminated with luminescent lamps for 14 h per day, with an illumination of 2 klx on the side surface and a temperature of 20 ± 1°ë .Americium was added to water in the form of a water solution of americium nitrate, 241 Am(NO 3 ) 3 ; then, pH was adjusted to 7 by adding NaOH, and the plants were placed into the water. During the experiment, pH 7 was maintained. The initial radioactivity of 241 Am in the water was 1340 ± 50 Bq/l.To estimate the strength of americium binding by the plant biomass, we performed chemical fractionation as described earlier [5].To measure the 241 Am radioactivity accumulated by the biomass, leaves and stems were dried until their weight became constant and then dissolved in a mixture of 30% hydrogen peroxide and 1 M nitric acid while heating. The 241 Am activity in the resultant solutions and in the water from experimental cylinders was measured by means of a γ -spectrometer with an ultrapure germanium detector (Canberra, United Stat...

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Ultrastructural and Photosynthetic Features of Leaves and Stems of Elodea canadensis

Cited by 26 publications

References 25 publications

Anatomia das raízes de Bacopa salzmanii (Benth.) Wettst. Ex Edwall e Bacopa Monnierioides (Cham.) Robinson (Scrophulariaceae) em ambientes aquático e terrestre

Anatomia das raízes de Bacopa salzmanii (Benth.) Wettst. Ex Edwall e Bacopa Monnierioides (Cham.) Robinson (Scrophulariaceae) em ambientes aquático e terrestre

Structural characterization of photosynthetic cells in an amphibious sedge, Eleocharis vivipara, in relation to C3 and C4 metabolism

New Data on the Accumulation of Americium-241 by Photoassimilation Organs of the Aquatic Plant Elodea canadensis

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