The structure of rice roots grown in aerobic and anaerobic environments

John, C. D.

doi:10.1007/bf00010390

Cited by 23 publications

(8 citation statements)

References 6 publications

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“…Segundo Barratt (1916), Hulbary (1944), Dale (1957), Justin & Armstrong (1987), Armstrong et al (1994) e Bona & Morretes (1997), a origem, a estrutura do aerênquima e a percentagem de área lacunar são bastante variáveis entre os diferentes táxons. Aerênquima de origem esquizógena, como observado nas espécies de Bacopa estudadas, é mais comum em órgãos aéreos (Sculthorpe 1967 John (1977) e Justin & Armstrong (1987). O padrão de colapso celular confere com o tipo gramináceo referido por Justin & Armstrong (1987).…”

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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“…Aerenchyma formation is observed in cortical tissue 8-10 mm above the root tip (Kawai et al 1998) and fully developed aerenchyma is observed at a distance of about 100 mm away from tip. However, no appreciable aerenchyma has been found in the apical 1-2 mm of rice roots, even under waterlogging (John 1977). In rice even no characteristic cell morphology differentiation has been observed in the dying cells from surrounding cells (Inada et al 2002).…”

Section: Ultrastructural Changes During Lysigenous Aerenchyma Formationmentioning

confidence: 97%

“…In general, formation of aerenchyma is accelerated in response to waterlogged environments during hypoxia e.g. in barley (John 1977) and maize (Jackson et al 1985a;Drew et al 2000). However, in root of rice, aerenchyma formation is constitutive type which takes place even in aerobic conditions (John 1977;Clark and Harris 1981), although the extent of aerenchyma formation is triggered by soil waterlogging (Das and Jat 1977;Justin and Armstrong 1991).…”

Section: Soil Waterlogging and Aerenchyma Developmentmentioning

confidence: 99%

“…in barley (John 1977) and maize (Jackson et al 1985a;Drew et al 2000). However, in root of rice, aerenchyma formation is constitutive type which takes place even in aerobic conditions (John 1977;Clark and Harris 1981), although the extent of aerenchyma formation is triggered by soil waterlogging (Das and Jat 1977;Justin and Armstrong 1991). Furthermore, studies on root aerenchyma formation in rice have also shown enhanced formation of aerenchyma, when O 2 deficiency was imposed in hydroponics (Colmer et al 1998;Colmer 2003a).…”

Section: Soil Waterlogging and Aerenchyma Developmentmentioning

confidence: 99%

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Lysigenous aerenchyma formation involves non-apoptotic programmed cell death in rice (Oryza sativa L.) roots

Joshi

Kumar

2011

Physiol Mol Biol Plants

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In waterlogged soil, deficiency of oxygen triggers development of aerenchyma in roots which facilitates gas diffusion between roots and the aerial environment. However, in contrast to other monocots, roots of rice (Oryza sativa L.) constitutively form aerenchyma even in aerobic conditions. The formation of cortical aerenchyma in roots is thought to occur by either lysigeny or schizogeny. Schizogenous aerenchyma is developed without cortical cell death. However, lysigenous gas-spaces are formed as a consequence of senescence of specific cells in primary cortex followed by their death due to autolysis. In the last stage of aerenchyma formation, a 'spoked wheel' arrangement is observed in the cortical region of root. Ultrastructural studies show that cell death is constitutive and no characteristic cell structural differentiation takes place in the dying cells with respect to surrounding cells. Cell collapse initiation occurs in the center of the cortical tissues which are characterized by shorter with radically enlarged diameter. Then, cell death proceeds by acidification of cytoplasm followed by rupturing of plasma membrane, loss of cellular contents and cell wall degradation, while cells nuclei remain intact. Dying cells releases a signal through symplast which initiates cell death in neighboring cells. During early stages, middle lamella-degenerating enzymes are synthesized in the rough endoplasmic reticulum which are transported through dictyosome and discharged through plasmalemma beneath the cell wall. In rice several features of root aerenchyma formation are analogous to a gene regulated developmental process called programmed cell death (PCD), for instance, specific cortical cell death, obligate production of aerenchyma under environmental stresses and early changes in nuclear structure which includes clumping of chromatin, fragmentation, disruption of nuclear membrane and apparent engulfment by the vacuole. These processes are followed by crenulation of plasma membrane, formation of electron-lucent regions in the cytoplasm, tonoplast disintegration, organellar swelling and disruption, loss of cytoplasmic contents, and collapse of cell. Many processes in lysing cells are structural features of apoptosis, but certain characteristics of apoptosis i.e., pycnosis of the nucleus, plasma membrane blebbing, and apoptotic bodies formation are still lacking and thus classified as non-apoptotic PCD. This review article, describes most recent observations alike to PCD involved in aerenchyma formation and their systematic distributions in rice roots.

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“…Since these internal air spaces in rice plants are particularly well developed in the culm (1) and roots (16), the ventilation system in rice plants plays an important role in transport of gases between the rhizosphere and the atmosphere. The absorption and release sites of gases are generally considered to be the stomata which are linked to intercellular air spaces in the leafblade.…”

mentioning

confidence: 99%

Mechanism of Methane Transport from the Rhizosphere to the Atmosphere through Rice Plants

Nouchi¹,

Mariko²,

Aoki³

1990

Plant Physiol.

349

174

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To clarify the mechanisms of methane transport from the rhizosphere into the atmosphere through rice plants (Oryza sativa L.), the methane emission rate was measured from a shoot whose roots had been kept in a culture solution with a high methane concentration or exposed to methane gas in the gas phase by using a cylindrical chamber. No clear correlation was observed between change in the transpiration rate and that in the methane emission rate. Methane was mostly released from the culm, which is an aggregation of leaf sheaths, but not from the leaf blade. Micropores which are different from stomata were newly found at the abaxial epidermis of the leaf sheath by scanning electron microscopy. The measured methane emission rate was much higher than the calculated methane emission rate that would result from transpiration and the methane concentration in the culture solution. Rice roots could absorb methane gas in the gas phase without water uptake. These results suggest that methane dissolved in the soil water surrounding the roots diffuses into the cell-wall water of the root cells, gasifies in the root cortex, and then is mostly released through the micropores in the leaf sheaths.Recent studies of ancient air trapped in polar ice cores (7,17) have shown that the concentration of atmospheric methane has more than doubled during the past 200 years and that during the last decade atmospheric methane has increased approximately 1% per year (4). Because methane is one of the so-called greenhouse gases, in addition to C02, N20, 03, and chlorofluorocarbons, the increase in atmospheric methane may cause an increase in the globally averaged surface temperature (19,25). About 80% of methane emissions are produced biologically by methanogenic bacteria in flooded soils and in the intestines ofdomestic animals (9). Rice (Oryza sativa L.) paddy fields are known to be a major source of methane (5) and the area of rice paddy fields in the world averaged over the last 35 years has increased 1.6% per year (13). Although a full explanation of increasing atmospheric methane concentration remains uncertain, the increasing area of rice paddy fields in the world is considered to be an important cause of the recent shifts in the atmospheric methane balance. Studies have found that methane emission from vegetated plots in rice paddy fields were much higher than from unvegetated plots (6, 14). Therefore, Cicerone and Shetter (6) proposed that methane emitted to the atmosphere from rice paddy fields is transported mostly through rice plants and not across the water-air interface via bubbles or molecular diffusion.In rice and other hydrophytes, it is well known that atmospheric 02 is transported to the submerged organs from the leaf parts above water through the aerenchyma and intercellular gas space systems by diffusion (2, 10, 15, 24) or by mass flow (8). Since these internal air spaces in rice plants are particularly well developed in the culm (1) and roots (16), the ventilation system in rice plants plays an important role in t...

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The structure of rice roots grown in aerobic and anaerobic environments

Cited by 23 publications

References 6 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

Lysigenous aerenchyma formation involves non-apoptotic programmed cell death in rice (Oryza sativa L.) roots

Mechanism of Methane Transport from the Rhizosphere to the Atmosphere through Rice Plants

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