Chlorophyll Biosynthetic Reactions during Senescence of Excised Barley (Hordeum vulgare L. cv IB 65) Leaves

Hukmani, Pinki; Tripathy, Baishnab C.

doi:10.1104/pp.105.4.1295

Cited by 36 publications

(22 citation statements)

References 28 publications

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“…White white mutant leaves; Green green mutant leaves. The data are mean ± SD from three experiments, each of which was performed in triplicate Stimulating kinetin effects on ALAD activity have been previously reported (Stobart et al 1972;Hukmani and Tripathy 1994). But under our experimental conditions, cytokinin application to etiolated barley seedlings with kinetin did not affect the activity (data not shown) and the protein level of ALAD (Fig.…”

Section: Resultsmentioning

confidence: 53%

“…Application of cytokinin to cucumber and barley increased the levels of plastid tRNA glu (Masuda et al 1994) and of transcripts encoding glutamyl-tRNA glu reductase (GluTR) participating in ALA synthesis (Masuda et al 1995;Bougri and Grimm 1996). Stimulatory effect of cytokinin on the activity of ALA dehydratase (ALAD) was reported in senescent leaves of barley (Stobart et al 1972;Hukmani and Tripathy 1994). Cytokinins strongly increased the level of mRNA encoding NADPH-protochlorophyllide oxidoreductase (POR) and the content of this enzyme in cucumber and lupine cotyledons (Kuroda et al 1996;Kusnetsov et al 1998;Kuroda et al 2001).…”

Section: Introductionmentioning

confidence: 94%

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Cytokinin effects on tetrapyrrole biosynthesis and photosynthetic activity in barley seedlings

Yaronskaya

Vershilovskaya

Poers

et al. 2006

Planta

134

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Cytokinin promotes morphological and physiological processes including the tetrapyrrole biosynthetic pathway during plant development. Only a few steps of chlorophyll (Chl) biosynthesis, exerting the phytohormonal influence, have been individually examined. We performed a comprehensive survey of cytokinin action on the regulation of tetrapyrrole biosynthesis with etiolated and greening barley seedlings. Protein contents, enzyme activities and tetrapyrrole metabolites were analyzed for highly regulated metabolic steps including those of 5-aminolevulinic acid (ALA) biosynthesis and enzymes at the branch point for protoporphyrin IX distribution to Chl and heme. Although levels of the two enzymes of ALA synthesis, glutamyl-tRNA reductase and glutamate 1-semialdehyde aminotransferase, were elevated in dark grown kinetin-treated barley seedlings, the ALA synthesis rate was only significantly enhanced when plant were exposed to light. While cytokinin do not stimulatorily affect Fe-chelatase activity and heme content, it promotes activities of the first enzymes in the Mg branch, Mg protoporphyrin IX chelatase and Mg protoporphyrin IX methyltransferase, in etiolated seedlings up to the first 5 h of light exposure in comparison to control. This elevated activities result in stimulated Chl biosynthesis, which again parallels with enhanced photosynthetic activities indicated by the photosynthetic parameters F(V)/F(M), J (CO2max) and J (CO2) in the kinetin-treated greening seedlings during the first hours of illumination. Thus, cytokinin-driven acceleration of the tetrapyrrole metabolism supports functioning and assembly of the photosynthetic complexes in developing chloroplasts.

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Section: Resultsmentioning

confidence: 53%

Section: Introductionmentioning

confidence: 94%

Cytokinin effects on tetrapyrrole biosynthesis and photosynthetic activity in barley seedlings

Yaronskaya

Vershilovskaya

Poers

et al. 2006

Planta

134

View full text Add to dashboard Cite

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“…The remaining seedlings were sprayed with 5 mM ALA and kept in the dark for 6 h under appropriate stress conditions (Chakraborty and Tripathy 1992) after which the cotyledons were harvested. Immediately after harvesting, all cotyledons were quickly homogenized in darkness in 90% ammonical acetone (acetone:0.1 N NH 4 OH; 9:1,v/v) (Hukmani and Tripathy 1994). Hexane extraction and pigment analysis were done as described below.…”

Section: Methodsmentioning

confidence: 99%

Acclimation of chlorophyll biosynthetic reactions to temperature stress in cucumber ( Cucumis sativus L.)

Tewari

Tripathy

1999

Planta

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The adaptive responses of the greening process of plants to temperature stress were studied in cucumber (Cucumis sativus L. cv. Poinsette) seedlings grown at ambient (25°C), low (7°C) and high (42°C) temperatures. Plastids isolated from these seedlings were incubated at dierent temperatures and the net syntheses of various tetrapyrroles were monitored. In plastids isolated from control seedlings grown at 25°C, the optimum temperature for synthesis of Mg-protoporphyrin IX monoester or protochlorophyllide was 35°C. Temperature maxima for Mg-protoporphyrin IX monoester and protochlorophyllide syntheses were shifted to 30°C in chill-stressed seedlings. The net synthesis of total tetrapyrroles was severely reduced in heat-stressed seedlings and the optimum temperature for Mg-protoporphyrin IX monoester or protochlorophyllide synthesis shifted slightly towards higher temperatures, i.e. a broader peak was observed. To further study the temperature acclimation of seedlings with respect to the greening process, tetrapyrrole biosynthesis was monitored at 25°C after pre-heating the plastids (28± 70°C) isolated from control, chill-and heat-stressed seedlings. In comparison to 28°C-pre-heated plastids the percent inhibition of protochlorophyllide synthesis in 40°C-pre-heated plastids was higher than for the control (25°C-grown) in chill-stressed seedlings and lower than for the control in heat-stressed seedlings. Maximum synthesis of total tetrapyrroles and protoporphyrin IX was observed when chloroplasts were heated at 50°C, which was probably due to heatinduced activation of the enzymes involved in protoporphyrin IX synthesis. Prominent shoulders towards lower or higher temperatures were seen in chill-stressed or heat-stressed seedlings, respectively. The shift in optimum temperature for tetrapyrrole biosynthesis in chill-and heat-stressed seedlings was probably due to acclimation of membranes possibly undergoing desaturation or saturation of membrane lipids. Proteins synthesized in response to temperature-stress may also play an important role in conferring stress-tolerance in plants.Abbreviations: ALA = 5-aminolevulinic acid; Chl = chlorophyll; Chlide = chlorophyllide; MP(E) = Mg-protoporphyrin IX and its monoester; Pchlide = protochlorophyllide; Proto IX = protoporphyrin IX

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“…A similar action was observed during the senescence of barley. In this grain, the exogenous application of kinetin retarded chlorophyll degradation, mainly because of a higher activity of those enzymes involved in the chlorophyll biosynthesis (Hukmani andTrepathy 1994, Kuroda et al 1990). …”

Section: Chlorophyllasementioning

confidence: 97%

Effect of exogenous application of gibberellic acid on color change and phenylalanine ammonia-lyase, chlorophyllase, and peroxidase activities during ripening of strawberry fruit (Fragaria x ananassa Duch.)

Martínez

Chaves

Añón

1996

J Plant Growth Regul

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Abstract. The effect of exogenously applied gibberellic acid (GA3) on the postharvest color change of strawberry fruit was evaluated through their external color and surface color parameters. A significant delay on color evolution was observed in fruits treated with GA 3. The evolution of activities of phenylalanine ammonia-lyase (PAL), chlorophyllase, and peroxidase was also analyzed. PAL activity increased during strawberry ripening, but in fruits treated with GA 3 the increase in such activity was slower, and, probably as consequence, the development of red color was delayed. Moreover, the activity of chlorophyllase and peroxidase, enzymes possibly involved in chlorophyll metabolism, decreased during strawberry ripening. However, a delay was observed in the decrease of such activities in GA3-treated fruits.

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Chlorophyll Biosynthetic Reactions during Senescence of Excised Barley (Hordeum vulgare L. cv IB 65) Leaves

Cited by 36 publications

References 28 publications

Cytokinin effects on tetrapyrrole biosynthesis and photosynthetic activity in barley seedlings

Cytokinin effects on tetrapyrrole biosynthesis and photosynthetic activity in barley seedlings

Acclimation of chlorophyll biosynthetic reactions to temperature stress in cucumber ( Cucumis sativus L.)

Effect of exogenous application of gibberellic acid on color change and phenylalanine ammonia-lyase, chlorophyllase, and peroxidase activities during ripening of strawberry fruit (Fragaria x ananassa Duch.)

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