Estimates of a mean speed of translocation in leaves of oryza sativa L

Troughton, John H.; Chang, F.H.; Currie, B. G.

doi:10.1016/0304-4211(74)90131-x

Cited by 12 publications

(3 citation statements)

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“…From previously reported data on the speed during prolonged light or on transfer to darkness (21,35) Figure 12, A and B. In both cases, the results confirmed the previous conclusions, i.e.…”

Section: General Features Of Carbon 1 1 Translocationsupporting

confidence: 90%

“…In this paper, we report about 100 measurements of speed; the same technique and species are used and the influence of one environmental parameter, light, is investigated. Our experience with the carbon 11 isotope during these experiments, and in those reported previously, has established that 'IC can be used in a routine manner to monitor several attributes of the translocation system in higher plants (21,35,36).…”

Section: General Features Of Carbon 1 1 Translocationmentioning

confidence: 65%

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Relations between Light Level, Sucrose Concentration, and Translocation of Carbon 11 in Zea mays Leaves

Troughton¹,

Currie²,

Chang

1977

Plant Physiol.

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The mechanism of carbon transport in Zea mays leaves was investigated using carbon 11 which is a short lved (half-lfe 20.4 min) positronemitting isotope. The gamma radiation produced on annihilation allows in vivo or nondestructive measurement of the isotope and the short halflife allows many measurements of trandocation to be made on the same leaf within the same day.Carbon 11 produced by the 10B (d,n)"C nuclear reaction was converted to "CO2, fed to a leaf as a short pulse, and assimilated during photosynthesis. The progress of the radioactive pulse along the leaf in the phloem was monitored in severd positions simultaneously with counters. The counters were Nal crystals with photomaltipliers and the output was amplified, passed to single channel analyzers, and the counts accumulated for 20 seconds every 30 seconds. Corrections were made for the half-life and background radiation by computer, and the results were displayed on a high speed plotter. Information derived from the corrected data induded the speed of translocation, the shape of the radioactive carbon pulse, and the influence of light and distance along the leaf on these parmeters. The plants were kept under controlled environment conditions during all measurements.A speed was derived from the time displacement of the midpoint of the front of the pulse, measured at two positions along the leaf. This was an apparent mean speed of translocation because it averaged a variation in speed with distance, variation in speed between or within sieve tubes, and it averaged the mean speed of all of the particles in the pulse.A wide range of speeds of translocation from 0.25 to 11 cm min-' was observed but most of the variability was due to the variation in light available to the leaf. For example, the speed of translocation was proportional to the light level on either the whole plant or individual leaf. Shading of the leaf established that the light effect was not localized in either the feeding area or in the portion of the leaf on which the measurements were made. It was proposed that the speed was dependent on the proportion of the leaf in the light upstream from the last counter. The speed of translocation was relatively independent of the stage of growth of the plant, age of the leaf, and the time during the diurnal light cyde. Data Carbon translocation is an integral component of the growthand yield-determining processes in higher plants. To characterize long distance C transport, it will be necessary to measure the speed and sugar concentration of the solution and the crosssectional area of the sieve tubes active in translocation. Other data, such as the turgor pressure and the water, ion, and sugar exchange rates of the sieve tubes, are required to establish the mechanism of C transport and explain the cause of the variation in C translocation between species, or between plants, under different environmental conditions.Routine measurement of some of these translocation parameters has not been easy. Through the development of techniques to prod...

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Section: General Features Of Carbon 1 1 Translocationsupporting

confidence: 90%

Section: General Features Of Carbon 1 1 Translocationmentioning

confidence: 65%

Relations between Light Level, Sucrose Concentration, and Translocation of Carbon 11 in Zea mays Leaves

Troughton¹,

Currie²,

Chang

1977

Plant Physiol.

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“…Several methodologies can be used. Using scintillation detectors, with radiation shielding to delineate regions of interest (ROI), a range of phenomena has been studied concerning phloem physiology, for example in root apices (Pritchard et al, 2004), roots (Farrar et al, 1995), properties of the long-distance transport pathway (Troughton et al, 1974;Minchin and Thorpe, 1984), in leaves (Pickard et al, 1993), and in reproductive organs (Roeb and Britz, 1991;Thorpe et al, 1993). The low spatial resolution of this method is not a problem for measurement of long-distance tracer transport since the flow at the boundary from one contiguous region to another can be inferred (e.g., Minchin and Thorpe, 2003).…”

Section: Introductionmentioning

confidence: 99%

High-Resolution in vivo Imaging of Xylem-Transported CO2 in Leaves Based on Real-Time 11C-Tracing

Hubeau

Thorpe

Mincke

et al. 2019

Front. For. Glob. Change

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Plant studies using the short-lived isotope 11 C to label photosynthate via atmospheric carbon dioxide (CO 2 ), have greatly advanced our knowledge about the allocation of recent photosynthate from leaves to sinks. However, a second source for photosynthesis is CO 2 in the transpiration stream, coming from respiration in plant tissues. Here, we use in vivo tracing of xylem-transported 11 CO 2 to increase our knowledge on whole plant carbon cycling. We developed a new method for in vivo tracing of xylem-transported CO 2 in excised poplar leaves using 11 C in combination with positron emission tomography (PET) and autoradiography. To show the applicability of both measurement techniques in visualizing and quantifying CO 2 transport dynamics, we administered the tracer via the cut petiole and manipulated the transport by excluding light or preventing transpiration. Irrespective of manipulation, some tracer was found in main and secondary veins, little of it was fixed in minor veins or mesophyll, while most of it diffused out the leaf. Transpiration, phloem loading and CO 2 recycling were identified as mechanisms that could be responsible for the transport of internal CO 2 . Both 11 C-PET and autoradiography can be successfully applied to study xylem-transported CO 2 , toward better understanding of leaf and plant carbon cycling, and its importance in different growing conditions.

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Light Level and the Mean Speed of Translocation in Zea Mays Leaves

Troughton¹

1975

Environmental and Biological Control of Photosynthesis

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Estimates of a mean speed of translocation in leaves of oryza sativa L

Cited by 12 publications

References 0 publications

Relations between Light Level, Sucrose Concentration, and Translocation of Carbon 11 in Zea mays Leaves

Relations between Light Level, Sucrose Concentration, and Translocation of Carbon 11 in Zea mays Leaves

High-Resolution in vivo Imaging of Xylem-Transported CO2 in Leaves Based on Real-Time 11C-Tracing

Light Level and the Mean Speed of Translocation in Zea Mays Leaves

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