Effect of Gravity Compensation on the Geotropic Sensitivity of <i>Avena</i> Seedlings

Dedolph, R. R.; Naqvi, S. M.; Gordon, Solon A.

doi:10.1104/pp.40.5.961

Cited by 20 publications

(13 citation statements)

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“…The increases in starch grain diameter observed here under gravity compensation result in amyloplasts of greater size and density. These findings are consistent with reports (4,6) that clinostat rotation increases the geotropic curvature in response to subsequent stimulation, and with the hypothesis that amyloplasts have a role in the geoperceptive mechanism.…”

Section: Resultssupporting

confidence: 82%

“…Furthermore, gravity compensation appears to increase shoot geosensitivity. If the shoots of compensated cereal grain seedlings are subsequently gravity-stlmulated by placing them in a stationary horizontal position, they will curve more than shoots that were not compensated prior to geostimulation (6,24).In the cells of the geoperceptive regions of many plants, mobile, dense amyloplasts fall toward the physically lower wall during geotropic stimulation. The "statolith" amyloplasts observed in these geoperceptive regions are often ultrastructurally distinct (higher starch-stroma ratio) from those found elsewhere in the plant (14) …”

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confidence: 99%

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confidence: 99%

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Amyloplast Size and Number in Gravity-compensated Oat Seedlings

Hinchman¹,

Gordon²

1974

Plant Physiol.

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In recent years increasing emphasis has been placed on the clinostat as a substitute for the free-fall environment, or as a test situation preliminary to free-fall experiments utilizing orthogeotropic plants. Clinostats are devices designed to reorient the plant continuously by rotation on a horizontal axis, so that the tropic effect of gravity direction is nullified or "compensated." Gravity-compensated plants grow in the direction imparted by the original orientation of the plant or seed and show no directional response to the continuously changing directional vector of gravity. Furthermore, gravity compensation appears to increase shoot geosensitivity. If the shoots of compensated cereal grain seedlings are subsequently gravity-stlmulated by placing them in a stationary horizontal position, they will curve more than shoots that were not compensated prior to geostimulation (6,24).In the cells of the geoperceptive regions of many plants, mobile, dense amyloplasts fall toward the physically lower wall during geotropic stimulation. The "statolith" amyloplasts observed in these geoperceptive regions are often ultrastructurally distinct (higher starch-stroma ratio) from those found elsewhere in the plant (14)

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Section: Resultssupporting

confidence: 82%

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Amyloplast Size and Number in Gravity-compensated Oat Seedlings

Hinchman¹,

Gordon²

1974

Plant Physiol.

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“…Both geotropic cuirvature of coleoptiles and root growth are enhanced by horizontal clinostat rotation and concomitant nullification of the directional component of the gravitational stimulus (3). Thouigh coleoptile cturvature and root growth are auxin dependent, the observed horizontal clinostat-induiced growth differences are not explicable on bases of auxin economy (4).…”

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confidence: 96%

Simulated Low-gravity Environments and Respiratory Metabolism in Avena Seedlings

et al. 1966

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Summary. Using horizontal and vertical axis clinostats and sand-grown oat seedlings (Azvena sativa), it was found that horizontal clinostat rotation at 2 rpm increased respiration and inorganic and organic phosphorus content of seedlings. Increased coleoptile geotropism and root growth are attributed to rotational nullification of-tlte directionar component of the gravitational stimulus. These growth modifications are mechanistically explicable by the relationship between plant metabolism and atixin concentration in these organs.Both geotropic cuirvature of coleoptiles and root growth are enhanced by horizontal clinostat rotation and concomitant nullification of the directional component of the gravitational stimulus (3). Thouigh coleoptile cturvature and root growth are auxin dependent, the observed horizontal clinostat-induiced growth differences are not explicable on bases of auxin economy (4). These atlxin studies, however, infer that horizontal clinostat rotation resutlts in higher rates of respiration.To directly test this inference, respiration rates of plants grown with horizontal or vertical axis clinostat rotation were compared. These comparisons, based on rates of CO., evoluition, were suipplemented by data on the effect of gravity on phosphorus metabolism. This manuiscript deals with the resuilts of these respiration measuirements and the fuirther interpretation of past resuilts on a basis of these new data. Materials and MethodsThe measutrement of respiration by CO2 evolution requires that the rate of evolution be adjutsted for differences in sample size in the variotus treat

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“…6,14). Several authors have observed increased sensitivity to gravistimulation or to photostimulation (e.g., 8,11,35), as well as increased curvature in response to applied auxins (9). Attenuation of flowering in Xanthium by clinostating was reported by Hoshizaki and co-workers (15).…”

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confidence: 97%