Labeling Pattern of Translocated Stachyose in Squash

Hendrix, John E.

doi:10.1104/pp.43.10.1631

Cited by 26 publications

(21 citation statements)

References 20 publications

(19 reference statements)

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“…Figure 3 gives a clear picture of the ratio of "C-sucrose to "C-stachyose with distance from the blade. This is quite different from the results when "CO2 was supplied to the blade (6). Under those conditions, 60% to 80% of the "C in the petiole was in stachyose and only about 20% in sucrose.…”

Section: Resultscontrasting

confidence: 53%

“…It becomes apparent from the data reported here and those previously presented for 'CO, labeling (5,6) that the changing ratios of "C in these two compounds (Fig. 3) do not represent metabolic interconversions within the transport system, but rather a history of conditions within the blade.…”

Section: Resultssupporting

confidence: 47%

“…Seeds of Cucurbita pepo L. var melopepo torticallis Bailey were germinated in vermiculite in the greenhouse. After the seedlings had emerged, they were transferred to modified Meyer's solution (6). When the second true leaf was fully expanded, the plants were transferred from the greenhouse to a hood where 1000 ft-c was supplied by 300-w reflector flood incandescent lamps.…”

Section: Methodsmentioning

confidence: 99%

“…Squash plants, as well as several other species, transport stachyose (3,4,6,(8)(9)(10). The selection of the nonreducing sugar that is translocated by a given species could be under the control of the phloem loading system.…”

mentioning

confidence: 99%

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Translocation of Sucrose by Squash Plants

Hendrix

1973

Plant Physiol.

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Sucrose-'4C was fed to the leaf blades of squash plants (Cucurbita pepo L. var. melopepo torticallis Bailey) for 30 or 60 minutes. Petioles of treated plants were cut into sections and extracted. The majority of the "C within the petiole was in sucrose rather than stachyose, the sugar that is transported by the squash plants when 'CO2 is supplied. This indicates that the phloem loading system of squash plants is not the system that specifies which sugar is transported.Sucrose is translocated in the phloem of most plants that have been studied; however, some plants transport other nonreducing sugars and sugar alcohols (2, 9, 11). Squash plants, as well as several other species, transport stachyose (3,4,6,(8)(9)(10). The selection of the nonreducing sugar that is translocated by a given species could be under the control of the phloem loading system. Alternatively, the selection might be dependent on which nonreducing sugar is supplied to that system. Webb and Gorham (8) reported that export from young squash leaves did not start until these leaves started producing stachyose, even though they produced large amounts of sucrose earlier in their development. This suggests that the transport system of squash does not load sucrose. Trip et al. (7) attempted to study the selectivity of the white ash transport system by supplying several "C-labeled sugars and sugar alcohols to the leaves. They harvested the plants 24 hr after the labeled compounds were introduced. With such a long elapsed time, it is very likely that the patterns they saw resulted from differential rates of metabolism, and from (as they said) ". . . differential rates of accumulation rather than translocation." In the studies reported here, squash plants were harvested 30 and 60 min after introduction of "C-sucrose. The results indicate that sucrose is readily transported by squash plants. water. The day before the "C-sucrose was supplied, all leaves greater than one-fifth expanded, except the youngest fully expanded leaf, were removed. This procedure of removing all other transporation sinks ensured a strong flow through the xylem into the treated leaf, thereby ensuring that the supplied sugar would not be drawn into the petiole by a reverse flow in the xylem. To ensure that these precautions were effective, a preliminary experiment was done using "C-glucose. The pattern of labeled compounds found in the petiole was similar to that found when sucrose was used. If the sugars had been drawn into the petiole by reverse flow through the xylem, the proportion of the label in glucose should have been very high. This indicates that reverse flow was not occurring. MATERIALS AND METHODSExperimental Procedure. The "C-sucrose, 5.2 mc/mmole, was introduced through the second lateral vein from the base of the blade by the reverse flap method of Biddulph (1). During the translocation period, the plants were under the incandescent lights described above. After the elapsed times indicated, the petiole was cut free from the blade and stem, then cut into section...

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Section: Resultscontrasting

confidence: 53%

Section: Resultssupporting

confidence: 47%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Translocation of Sucrose by Squash Plants

Hendrix

1973

Plant Physiol.

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“…1). The observation that whiteflies feeding on pumpkin, which translocates raffinose-series sugars (3,6), produced nearly fivefold less trehalulose (3), supports this idea. Currently, we are conducting research to determine if isomaltulose synthase (EC 5.4.99.10), the enzyme presumably responsible for trehalulose biosynthesis, is present in whitefly mycetocytes.…”

Section: Resultssupporting

confidence: 66%

High Performance Liquid Chromatography Analysis of Carbohydrates of Cotton-Phloem Sap and of Honeydew Produced by Bemisia tabaci Feeding on Cotton

Tarczynski

Byrne²,

Miller³

1992

Plant Physiol.

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Phloem sap from cotton (Gossypium hirsutum L.) was collected from young and mature leaves by the aphid-stylet technique.Exudate was analyzed for carbohydrates by HPLC using sensitive pulsed amperometric detection. The predominant carbohydrate present (>90%) was identified as sucrose. A second, unidentified compound that was not one of the more commonly translocated sugars was detected in mature leaves. Carbohydrates in honeydew produced by the sweet-potato whitefly (Bemisia tabaci [Genn.]) feeding on cotton were sucrose, glucose, fructose, trehalulose, and a series of oligosaccharides.A number of phloem-feeding insects have been reported to affect adversely the growth of their plant hosts (e.g. 10). The relationship between the sweet-potato whitefly, Bemisia tabaci (Genn.) (Homoptera: Aleyrodidae), and the host plant, cotton, Gossypium hirsutum L., is an important example. Whitefly populations can exceed 100 individuals/cm2 of cotton-leaf surface (D.N.B., personal observation) and can extract enough phloem sap to affect directly crop yields (1 1). This insect also serves as a vector for at least 14 viral pathogens (2). The honeydew produced by whiteflies supports the growth of sooty mold fungi, e.g. Capnodium spp., which can lead to photosynthetic inhibition (8).In this investigation, we utilized the aphid-stylet technique to characterize qualitatively the carbohydrate composition of phloem sap from short-staple cotton. Cotton-phloem sap has not previously been characterized, presumably because of the difficulties involved in phloem-sap extraction. We also examined the carbohydrates found in honeydew produced by B. tabaci feeding on cotton. The data obtained will improve our understanding of the carbohydrates translocated by cot- ' Sap and Honeydew CollectionPhloem sap was obtained from two types of leaves: (a) young and expanding (<3 cm in length), and (b) mature and fully expanded (approximately 12 cm in length). Phloem sap from a total of three plants was analyzed. The concentration of cotton aphids, Aphis gossypii Glover, feeding on these plants was approximately three aphids/cm2 of leaf (abaxial surface); these insects were used as a tool for phloem-sap extraction. Collections of phloem sap were made by severing the aphid-stylet bundles, which were inserted into the minor veins of attached leaves. Stylets were severed by a microcautery device similar to that described previously (5,14

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Lipid Polymers and Associated Phenols, Their Chemistry, Biosynthesis, and Role in Pathogenesis

Kolattukudy

1977

The Structure, Biosynthesis, and Degradation of Wood

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Labeling Pattern of Translocated Stachyose in Squash

Cited by 26 publications

References 20 publications

Translocation of Sucrose by Squash Plants

Translocation of Sucrose by Squash Plants

High Performance Liquid Chromatography Analysis of Carbohydrates of Cotton-Phloem Sap and of Honeydew Produced by Bemisia tabaci Feeding on Cotton

Lipid Polymers and Associated Phenols, Their Chemistry, Biosynthesis, and Role in Pathogenesis

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