Sugar translocation in two members of the cucurbitaceae

Hendrix, John E.

doi:10.1016/0304-4211(82)90200-0

Cited by 21 publications

(11 citation statements)

References 7 publications

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“…Among the phreatophytes, the winter-deciduous species had considerably lower 1 than the summer-deciduous and stem-photosynthetic phreatophytic species. The root succulent (Hendrix 1982) Cucurbita digitata had the highest 1 values.…”

Section: Resultsmentioning

confidence: 99%

Comparative Water Relations of Phreatophytes in the Sonoran Desert of California

Nilsen¹,

Sharifi²,

Rundel³

1984

Ecology

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Abstract. The seasonal and diurnal water relations were compared among six desert phreatophytes, two evergreen shrubs, and one deciduous shrub. All species were located in one wash woodland in the Sonoran Desert of southern California. There are several mechanisms by which these phreatophytes have adapted to the desert environment. One group of winter-deciduous phreatophytes (Olneya tesota, Prosopis glandulosa, and Acacia greggii) experienced summer midday leaf water potentials below -4.0 MPa. These phreatophytes had a series of physiological mechanisms for tolerating summer water stress, including seasonal and diurnal osmotic adjustment and the maintenance of high leaf conductance at low leaf water potential. Osmotic adjustment of these three phreatophytes was similar to or greater than that of two evergreen species (Larrea tridentata and Simmondsia chinensis). Dalea spinosa, a stem-photosynthetic phreatophyte, avoided water stress by maintaining a very small leaf area. The summer-deciduous phreatophytes (Hyptis emoryi, and Chilopsis linearis) demonstrated mechanisms of drought avoidance such as change in leaf biomass and low summer leaf conductance. Little osmotic adjustment occurred in the summer-deciduous phreatophytes. Ecological Society of AmericaThe phreatophytic species studied in this investigation have evolved adaptations to water stress that are similar to those of deciduous and evergreen shrubs of the Sonoran Desert. Desert phreatophytes are a complex group of species with varied adaptive mechanisms to tolerate or avoid drought and should not be considered simply as a group of species that avoid desert water stress by utilizing deep ground water unavailable to other desert species of drought tolerance and avoidance.

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Section: Resultsmentioning

confidence: 99%

Comparative Water Relations of Phreatophytes in the Sonoran Desert of California

Nilsen¹,

Sharifi²,

Rundel³

1984

Ecology

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“…Oligosaccharides of the raffinose family, in particular stachyose, are important phloem transport sugars in many members ofthe Cucurbitaceae (6,12,13,17,19). Stachyose concentrations in leaves and stems can often rival those of sucrose (12,16), and in this respect, the leaf of Xerosicyos did not appear to differ from other cucurbits as the concentration of stachyose in Xerosicyos leaf discs was also roughly equivalent to that of sucrose (Table II).…”

Section: Discussionmentioning

confidence: 95%

“…We now report that mature leaf tissues ofXerosicyos, in common with other nonsucculent members of the Cucurbitaceae (e.g. Cucurbita pepo [19]; Cucurbita foetidissima, Echinocystis lobata [6]; Cucumis sativus [12,13]; Cucumis melo [ 17]) possess the capacity for synthesis ofstachyose and other transport oligosaccharides of the raffinose family. In this plant, as was previously indicated for the nonsucculent plant C. pepo (2, 5, 1 1), the synthesis of these sugars may occur prior to phloem loading, in the photosynthetic mesophyll tissues.…”

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confidence: 88%

Stachyose Synthesis in Source Leaf Tissues of the CAM Plant Xerosicyos danguyi H. Humb.

Madore¹,

Mitchell²,

Boyd³

1988

Plant Physiol.

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MATERIALS AND METHODS Leaf tissues from Xerosicyos danguyi H. Humb., a succulent member of the Cucurbitaceae, were found to possess both galactinol synthase activity and the capacity for photosynthetic production of stachyose, the phloem transport oligosaccharide common to other nonsucculent cucurbits. The amounts of stachyose isolated from leaf tissues, and the extractable activity of galactinol synthase, were somewhat higher in leaf tissues obtained from plants operating in the Crassulacean acid metabolism (CAM) mode (well watered plants) compared to leaf tissues from plants operating in the CAM-idling mode (water-stressed plants). In contrast, in leaf discs, the photosynthetic incorporation of label into stachyose foliowing pulse labeling with 14C02 was similar for stressed and for nonstressed tissues. Stachyose could be extracted from, and was synthesized photosynthetically by, leaf discs which contained no vascular tissues, indicating that synthesis of stachyose can occur in photosynthetic mesophyll cells of Xerosicyos.

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“…In the Cucurbitaceae, stachyose appears to be the predominant transport sugar (12, 28, 29) rather than sucrose (31); however, raffmose and small amounts of verbascose also may be translocated (12). There is evidence that sucrose is also a transport sugar in some of these species (12, 28 (9,25). In the peduncle, stachyose is metabolized to sucrose which apparently enters the fruit and is further metabolized to glucose and fmctose (9, 20).…”

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confidence: 99%

mentioning

confidence: 99%

Carbohydrate Changes during Maturation of Cucumber Fruit

Handley¹,

Pharr²,

McFeeters³

1983

Plant Physiol.

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Raffmose saccharides occur as storage carbohydrate in seeds of legumes (14,15) and other species (4,15,24) and in vegetative tissues of a wide range of plants (6,22, 30). In the Cucurbitaceae, stachyose appears to be the predominant transport sugar (12, 28, 29) rather than sucrose (31); however, raffmose and small amounts of verbascose also may be translocated (12). There is evidence that sucrose is also a transport sugar in some of these species (12, 28 (9,25). In the peduncle, stachyose is metabolized to sucrose which apparently enters the fruit and is further metabolized to glucose and fmctose (9, 20).The recent report of raffinose saccharides in the mature seeds of C. sativus 'Calypso' (11) suggests that in situ synthesis of these sugars occurs in the developing seed, particularly since these sugars were not detected by paper chromatography in the fleshy portions of the cucumber fruit (20). There is the possibility, however, that this method of analysis failed to detect these sugars if they were restricted to the vascular tissues of the fruit. They might have been diluted by the high levels of glucose and fructose in the nonvascular tissues.This study was conducted to determine if in situ synthesis is responsible for the appearance of raffinose and stachyose in maturing cucumber seeds. To answer this question, changes in carbohydrate levels within the mesocarp, endocarp, and seed of maturing cucumber fruit were measured. In addition, galactinol synthase activity, the first unique enzyme in raflmose saccharide biosynthesis (7,10,11,16,19), and the sugars in funiculi were determined. In this study, decrease in endocarp pH was used as an index of fruit maturation (21). To determine if this was an adequate estimate of maturity, a separate study was conducted comparing this decrease in pH with a loss in peel Chl. Also, the organic acids malate and citrate were assayed from endocarp tissue during fruit maturation. MATERIALS AND METHODSPlant Material and Sampling Procedures. Cucumber (Cucumis sativus L.) fruit utilized in these studies were harvested from plants of cv Calypso, grown in field plots in Raleigh (except as noted below). For sugar and starch analysis offruit tissues, three separate harvests were made during the growing season. Fruit were hand harvested in early morning, washed, and separated into nine different categories based on the pH of the endocarp tissue (21). These pH categories ranged from 5.75 to 3.50 in 0.25 pH unit increments. Each fruit was cut crosswise at a point approximately one-third of the length of the fruit proximal to the blossom end. A pH electrode was inserted into the center of this one-third section, the pH recorded, and this section was discarded. The twothirds section was immediately chilled in ice until processed. Three fruit were collected for each pH category. All further operations were performed at 0°C.Endocarp tissue and seeds were scooped from the three fruit in each pH category. Endocarp tissue refers to the gelatinous tissue surrounding the seeds and includes the ...

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Sugar translocation in two members of the cucurbitaceae

Cited by 21 publications

References 7 publications

Comparative Water Relations of Phreatophytes in the Sonoran Desert of California

Comparative Water Relations of Phreatophytes in the Sonoran Desert of California

Stachyose Synthesis in Source Leaf Tissues of the CAM Plant Xerosicyos danguyi H. Humb.

Carbohydrate Changes during Maturation of Cucumber Fruit

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