Physiological Mechanisms of Plant Senescence

Brown, J. H.; Paliyath, Gopinadhan; Thompson, John E.

doi:10.1016/b978-0-12-668610-4.50011-2

Cited by 21 publications

(11 citation statements)

References 170 publications

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“…It appears that normal enzymatic defenses against activated oxygen diminish during senescence: While the glutathione (GSH) level, activities of catalase and superoxide dismutase decrease, the activity of peroxidase, a scavenger for hydrogen peroxide increases during senescence (Brown et al 1991). In parallel, mRNA levels for gluthatione-S-transferase (Smart et al 1995) and for a metallothionein possibly involved in protection of DNA from oxidative damage by free radicals (Buchanan-Wollaston 1994) increase during leaf senescence.…”

Section: Discussionmentioning

confidence: 98%

Isolation of cDNA clones for genes showing enhanced expression in barley leaves during dark-induced senescence as well as during senescence under field conditions

Kleber-Janke

Krupinska

1997

Planta

116

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Senescence of barley (Hordeum vulgare L. cv. Carina) primary foliage leaves was induced by transfer of the plants into darkness for 2 d. Under these conditions senescence was characterized by a light-reversible decline in the efficiency of photosystem II, and in chlorophyll and protein contents. To isolate senescence-associated genes a differential display of cDNA fragments amplified from reversely transcribed RNA was employed. By this method, gene expression in leaves of control plants collected at the onset of the dark period was compared with gene expression in senescing leaves collected at the end of the extended dark period. The expression of the genes represented by various differentially displayed cDNA fragments was examined by Northern blot hybridizations with RNA derived from primary foliage leaves before and after induction of senescence by darkness. In order to test whether these genes with enhanced expression during dark-induced senescence also show enhanced expression during natural senescence, Northern blot hybridizations were carried out with RNA samples prepared from flag leaves of barley plants during maturation and senescence under field conditions. Five of the cDNA fragments representing transcripts associated with dark-induced senescence, as well as with natural senescence, were selected as probes for screening a cDNA library from senescent flag leaves. With one probe a larger cDNA including a complete open reading frame with homology to the sequence of a known proteinase inhibitor was found. Another cDNA isolated by this means showed high sequence similarity with a gene coding for a 4-hydroxyphenylpyruvate dioxygenase. The other three larger cDNA clones isolated by this procedure so far do not show significant homologies with known sequences.

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Section: Discussionmentioning

confidence: 98%

Isolation of cDNA clones for genes showing enhanced expression in barley leaves during dark-induced senescence as well as during senescence under field conditions

Kleber-Janke

Krupinska

1997

Planta

116

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“…ABA has also been reported to be an important regulator in transporting assimilates to the developing seeds or fruits (Tietz et al 1981;Clifford et al 1986;Brenner and Cheikh 1995;Yang et al 1999). However, the proposal that ABA is involved in regulating both senescence and assimilate mobilization has remained disputable (Jones and Brenner 1987;Nooden 1988; Barratt et al 1989;Ober and Setter 1990;Brown et al 1991;Schussler et al 1991;de Bruijn and Vreugdenhil 1992;Yang et al 2000).…”

Section: Introductionmentioning

confidence: 98%

Abscisic acid and cytokinins in the root exudates and leaves and their relationship to senescence and remobilization of carbon reserves in rice subjected to water stress during grain filling

Yang

Zhang

Wang

et al. 2002

Planta

223

139

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The possible regulation of senescence-initiated remobilization of carbon reserves in rice (Oryza sativa L.) by abscisic acid (ABA) and cytokinins was studied using two rice cultivars with high lodging resistance and slow remobilization. The plants were grown in pots and either well-watered (WW, soil water potential = 0 MPa) or water-stressed (WS, soil water potential = -0.05 MPa) from 9 days after anthesis until they reached maturity. Leaf water potentials of both cultivars markedly decreased at midday as a result of water stress but completely recovered by early morning. Chlorophyll (Chl) and photosynthetic rate (Pr) of the flag leaves declined faster in WS plants than in WW plants, indicating that the water deficit enhanced senescence. Water stress accelerated starch remobilization in the stems, promoted the re-allocation of pre-fixed (14)C from the stems to grains, shortened the grain-filling period and increased the grain-filling rate. Sucrose phosphate synthase (SPS, EC 2.4.1.14) activity was enhanced by water stress and positively correlated with sucrose accumulation in both the stem and leaves. Water stress substantially increased ABA but reduced zeatin (Z) + zeatin riboside (ZR) concentrations in the root exudates and leaves. ABA significantly and negatively, while Z+ZR positively, correlated with Pr and Chl of the flag leaves. ABA, not Z+ZR, was positively and significantly correlated with SPS activity and remobilization of pre-stored carbon. Spraying ABA reduced Chl in the flag leaves, and enhanced SPS activity and remobilization of carbon reserves. Spraying kinetin had the opposite effect. The results suggest that both ABA and cytokinins are involved in controlling plant senescence, and an enhanced carbon remobilization is attributed to an elevated ABA level in rice plants subjected to water stress.

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“…Studies involving a non-yellowing mutant of Festuca pratensis support the idea that the hydrolysis of thylakoid galacto lipids plays an important role in the regulation of leaf senescence (Thomas 1987;Gepstein 1988). Since lipolytic enzymes are found in membranes of non-senescent tissues (Brown et al 1991), the protein synthesis in cytoplasm, which is necessary for chloroplast degradation (Stoddart & Thomas 1982;Cuello et al 1984) might lead to an increase in the activity of these enzymes.…”

Section: Resultsmentioning

confidence: 89%

“…High levels of LNA are esterified in thylakoid galactolipids (Douce & Joyard 1980) and it has been shown that the galactolipid LNA and/or linoleic acid content of thylakoids of chloroplasts in oat leaves increases during senescence in the dark (Dalgarn & Newman 1979). In addition, phospholipid-degrading enzymes in senescing membranes show a preference to degrade molecular species containing polyunsaturated fatty acids (Brown et al 1991) which, if extended to include the galactolipids, would lead to the liberation of LNA. The in vitro release of LNA from thylakoids through thylakoid-associated galactolipase activity has been demonstrated (O'Sullivan et al 1987;O'Sullivan & Dalling 1989),although in our case the quantity of LNA released must be very low since the SDS of the reaction medium inhibits galactolipase activity (O'Sullivan et al 1987).…”

Section: Resultsmentioning

confidence: 99%

Chlorophyll degradation by free radicals derived from linolenic acid in incubated barley thylakoids

Cuello

Cano

1993

Acta Botanica Neerlandica

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SUMMARY Using chloroplasts isolated from the senescent primary leaves of barley seedlings, the linolenic acid‐dependent degradation of chlorophyll was studied in incubated thylakoids. This reaction, measured by the decrease of absorbance at 672 nm, was produced by free radicals from linolenic acid oxidation and, thus, was inhibited by n‐propylgallate and α‐tocopherol, general scavengers of free radicals. Although the beginning of the reaction was delayed by heating the thylakoids, this process must be of a non‐enzymatic nature since it is not impeded by thermal treatment and it proved impossible to isolate a crude extract from thylakoids with a degradative enzymatic activity using a mixture of solubilized chlorophylls as substrate. The enzyme chlorophyll oxidase, described by others for thylakoids, was not found. In addition, the reaction of chlorophyll with the peroxidation products of linolenic acid seems to occur with the cooxidation of one or more carotenoids. Due to the high content of esterified linolenic acid in the thylakoid galactolipids, the degradation of chlorophyll studied here may have a physiological significance.

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Physiological Mechanisms of Plant Senescence

Cited by 21 publications

References 170 publications

Isolation of cDNA clones for genes showing enhanced expression in barley leaves during dark-induced senescence as well as during senescence under field conditions

Isolation of cDNA clones for genes showing enhanced expression in barley leaves during dark-induced senescence as well as during senescence under field conditions

Abscisic acid and cytokinins in the root exudates and leaves and their relationship to senescence and remobilization of carbon reserves in rice subjected to water stress during grain filling

Chlorophyll degradation by free radicals derived from linolenic acid in incubated barley thylakoids

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