Photosynthetic characteristics of mesophyll eells isolated from sunflower (helianthus annuus L.) leaves

Ranty, Benoı̂t; Cavalié, G.

doi:10.1007/bf00030050

Cited by 8 publications

(2 citation statements)

References 23 publications

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“…In respect to many studies carried out on photosynthesis preservation in protoplasts, stability of photosynthetic machinery strongly depends on plant material, time of enzymatic digestion and concentration of the cell wall-degrading enzymes (Wegmann and Mühlbach, 1973;Huber and Edwards, 1975;Morris and Thain, 1980;Ranty and CavaliØ, 1982). In the present study, freshly isolated protoplasts of S. hermonthica retained their photosynthetic activity; light use efficiency of photosynthesis was, however, 2 ± 3-fold lower than in the young leaves from which they were derived.…”

Section: Protoplast Characterisationmentioning

confidence: 42%

Characterisation of Simple In Vitro Cultures of Striga hermonthica Suitable for Metabolic Studies

Rousset¹,

Simier²,

Fer³

2003

Plant Biology

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The aim of this study is to develop simplified models for standardised screenings of xenobiotics, especially targeted against mannitol production, to control the harmful parasite, S. hermonthica. Chlorophyllous protoplasts and calli were produced from the young leaves of the parasite. Best yield from protoplast isolation was obtained when leaf segments were incubated at 30 °C, in the light, under shaking in an enzyme cocktail containing 2 % cellulase Onozuka R10, 0.1 % Pectolyase and sorbitol 1 M as the osmoticum. Oxygen exchange measurements, as well as labelling experiments with 14C‐bicarbonate, emphasised a significant decrease in photosynthetic capacity of protoplasts, mannitol remaining, however, a major primary product of photosynthesis. Initiation of cell cultures was unsuccessful and instability of protoplasts prevents their standardised utilisation for herbicide screening. In contrast, globular calli produced first on MS medium containing 0.5 mg L‐1 NAA, 2.5 mg L‐1 BAP and 2 % sucrose were stable for two years, after monthly subculturing on fresh medium. Sucrose substitution by mannose in the medium did not change kinetic growth and stability. Potential autotrophy was lost for calli by increasing exogenous sugar level. Biochemical analyses and labelling experiments with 14C‐bicarbonate or 14C‐sucrose or ‐mannose showed that carbon partitioning is modified in calli, in comparison with young leaves or protoplasts, sucrose or mannose accumulation being favoured in sucrose‐ or mannose‐fed calli, respectively. However, carbon flow towards mannitol was more marked in calli growing on high mannose medium. Stability and preservation of an active mannitol biosynthetic pathway allows planning of xenobiotic assays with calli as a simplified model for Striga hermonthica.

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Section: Protoplast Characterisationmentioning

confidence: 42%

Characterisation of Simple In Vitro Cultures of Striga hermonthica Suitable for Metabolic Studies

Rousset¹,

Simier²,

Fer³

2003

Plant Biology

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“…In particular, extent of leaf wilting (leaf angle) and solar tracking varied greatly from leaf to leaf and with time of day. Activations greater than 100% suggest that the 20-min preincubation we used in the assay for total activity was probably long enough to allow partial RuBPCase inactivation by phenolic compounds and/or metabolic effectors present in the extract (Ranty & Cavalie, 1982),…”

Section: Resultsmentioning

confidence: 99%

Responses of photosynthesis and carbohydrate‐partitioning to limitations in nitrogen and water availability in field‐grown sunflower^*

Fredeen

Gamon

Field

1991

Plant Cell & Environment

115

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Abstract. Sunflower plants (Helianthus annuus L., cv. CGL 208) were field‐grown in adjacent plots of varying resource availability. Control plants received irrigation (on a 4–5 d interval) and high levels of fertilizer nitrogen. Nutrient‐stress (N‐stress) plants received control levels of irrigation but no nutrient amendments and were determined to be nitrogen‐limited. Water‐stress (H2O‐stress) plants received control levels of fertilizer nitrogen, but no irrigation after approximately 6 weeks of plant growth. Both stress treatments reduced maximum and diurnal net photosynthesis (A) but resulted in different physiological or biochemical adjustments that tended to maintain or increase A per unit of resource (nitrogen or water) in shortest supply while decreasing the ratio of A per unit of abundant resource. Nutrient‐stress reduced total foliar nitrogen, foliar chlorophyll, and initial and total RuBPCase activities, thereby enhancing or preserving photosynthetic nitrogen‐use efficiency (NUE), defined as the maximum A observed per unit of leaf nitrogen, relative to the control and H2O‐stress treatments. In addition, N‐stress reduced photosynthetic water‐use efficiency (WUE), defined as the ratio of A to stomatal conductance to water vapour (g). The slope of A versus g increased with H2O‐stress. In addition, sunflower plants responded to H2O‐stress by accumulating foliar glucose and sucrose and by exhibiting diurnal leaf wilting, which presumably provided additional improvements in photosynthetic WUE through osmoregulation and reduction of midday radiation interception respectively. Photosynthetic NUE was decreased by H2O‐stress in that control levels of total nitrogen, foliar chlorophyll, and RuBPCase activities were maintained even after mean diurnal levels of A had fallen to less than 50% of the control level. We conclude that field‐grown sunflower manages a trade‐off between photosynthetic WUE and NUE, increasing use efficiency of the scarce resource while decreasing use efficiency of the abundant resource.

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Die physiologische Ertragsanalyse der Sonnenblume (Helianthus annuus L.) Teil I: Biologische Grundlagen und Ertragsbildung

Pasda¹,

Diepenbrock²

1990

Fett/Lipid

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Die Sonnenblume (Heliunthw unnuus L.) gehort zur Familie der Asteraceae (= Compositae) und ist neben dem Topinambur (Helianthus tuberosw L.) die einzige landwirtschaftliche Kulturpflanze der Gattung Helianthw. Das Ursprungsgebiet und Domestikationszentrum liegt in den USA. Vor rund 400 Jahren gelangte diese F'llanze iiber Spanien nach Europa und entwikkelte sich im 19. Jahrhundert in der UdSSR zu einer bedeutenden landwirtschaftlichen Kulturpflanze. Unter den einjiihrigen dlpflanzen nimmt sie heute weltweit den 3. Platz in der Anbaustatistik ein, mit dem Hauptanbaugebiet in der UdSSR. Die Sonnenblume verfiigt iiber ein tiefgehendes und weit verzweigtes Wurzelsystem. Dem Stengel, an dem 20 bis 30 Blatter inseriert sind, sitzt der endstiindige Bliitenkorb auf, der auBen von sterilen Zungenbliiten umgeben ist und sich aus bis zu 3500 Rohrenbliiten zusammensetzt. Die einzelne Rohrenbliite bliiht protandrisch, so daB Fremdbefruchtung bei weitem iiberwiegt: der ganze Korb bliiht von au5en nach innen ab. Die Frucht ist eine Nu5 mit Sonderform der Achiine. Die Gesamttrockenmasse erreicht Werte von bis zu 130 dt/ha, bei AchanenertrZgen von heute maximal 40 dt/ha. Die Sonnenblume ist zwar eine C3-Manze, aber aufgrund besonderer Eigenschaften besitzt sie fast genauso hohe Netto-Photosyntheseraten wie die C,-F'flanzen. Die Blattflache geht ab der Bliite stark zuriick. Die Aufrechterhaltung einer moglichst groBen Blattflache ist fur die Ertragsbildung aber von groBter Bedeutung, da die Assimilatversorgung fiir die Reservestoffspthese in den Achinen hauptsiichlich aus der laufenden Photosynthese und weniger durch die Verlagerung aus den vegetativen Pflanzenteilen erfolgt. Die Hauptreservestoffe sind Lipide und Proteine. Die Fettsaurezusammensetzung des Reservefettes ist durch hohe Anteile an Linolsaure sowie an Olsaure gekennzeichnet. Im Vergleich der Massenertriige ist die Sonnenblume den stiirkeerzeugenden Pflanzen, wie z. B. Mais, unterlegen. Auf einer energetischen Basis z. B. unter Zugrundelegung von Glucoseaquivalenten ist allerdings darauf hinzuweisen, daB die Sonnenblume fast genauso leistungsstark ist wie die C,-Art Mais.

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Photosynthetic characteristics of mesophyll eells isolated from sunflower (helianthus annuus L.) leaves

Cited by 8 publications

References 23 publications

Characterisation of Simple In Vitro Cultures of Striga hermonthica Suitable for Metabolic Studies

Characterisation of Simple In Vitro Cultures of Striga hermonthica Suitable for Metabolic Studies

Responses of photosynthesis and carbohydrate‐partitioning to limitations in nitrogen and water availability in field‐grown sunflower^*

Die physiologische Ertragsanalyse der Sonnenblume (Helianthus annuus L.) Teil I: Biologische Grundlagen und Ertragsbildung

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Photosynthetic characteristics of mesophyll eells isolated from sunflower (helianthus annuus L.) leaves

Cited by 8 publications

References 23 publications

Characterisation of Simple In Vitro Cultures of Striga hermonthica Suitable for Metabolic Studies

Characterisation of Simple In Vitro Cultures of Striga hermonthica Suitable for Metabolic Studies

Responses of photosynthesis and carbohydrate‐partitioning to limitations in nitrogen and water availability in field‐grown sunflower*

Die physiologische Ertragsanalyse der Sonnenblume (Helianthus annuus L.) Teil I: Biologische Grundlagen und Ertragsbildung

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Responses of photosynthesis and carbohydrate‐partitioning to limitations in nitrogen and water availability in field‐grown sunflower^*