Endogenous Gibberellin and Abscisic Acid Content as Related to Senescence of Detached Lettuce Leaves

Aharoni, Nehemia; Richmond, Amos

doi:10.1104/pp.62.2.224

Cited by 59 publications

(31 citation statements)

References 21 publications

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“…Senescence is affected by endogenous factors such as aging and hormones but also by environmental factors such as stress and nutrient supply (Gan and Amasino, 1997;Jing et al, 2002;Schippers et al, 2008). Specifically, the hormones ethylene and abscisic acid (ABA) have long been recognized as endogenous positive regulators of senescence (Hung and Kao, 2004;Lim et al, 2007), whereas gibberellin (GA) delays senescence in several species (Whyte and Luckwill, 1966;Goldthwaite and Laetsch, 1968;Chin and Beevers, 1970;Back and Richmond, 1971;Aharoni and Richmond, 1978;Kappers et al, 1998;Rosenvasser et al, 2006). Similarly, the supply of nutrients such as nitrogen, phosphorus, and metals is important during the senescence process (Lim et al, 2007;Wingler and Roitsch, 2008).…”

Section: Introductionmentioning

confidence: 99%

Antisense Inhibition of the 2-Oxoglutarate Dehydrogenase Complex in Tomato Demonstrates Its Importance for Plant Respiration and during Leaf Senescence and Fruit Maturation

et al. 2012

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Transgenic tomato (Solanum lycopersicum) plants expressing a fragment of the gene encoding the E1 subunit of the 2-oxoglutarate dehydrogenase complex in the antisense orientation and exhibiting substantial reductions in the activity of this enzyme exhibit a considerably reduced rate of respiration. They were, however, characterized by largely unaltered photosynthetic rates and fruit yields but restricted leaf, stem, and root growth. These lines displayed markedly altered metabolic profiles, including changes in tricarboxylic acid cycle intermediates and in the majority of the amino acids but unaltered pyridine nucleotide content both in leaves and during the progression of fruit ripening. Moreover, they displayed a generally accelerated development exhibiting early flowering, accelerated fruit ripening, and a markedly earlier onset of leaf senescence. In addition, transcript and selective hormone profiling of gibberellins and abscisic acid revealed changes only in the former coupled to changes in transcripts encoding enzymes of gibberellin biosynthesis. The data obtained are discussed in the context of the importance of this enzyme in both photosynthetic and respiratory metabolism as well as in programs of plant development connected to carbon-nitrogen interactions.

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Section: Introductionmentioning

confidence: 99%

Antisense Inhibition of the 2-Oxoglutarate Dehydrogenase Complex in Tomato Demonstrates Its Importance for Plant Respiration and during Leaf Senescence and Fruit Maturation

et al. 2012

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“…Some of these plant responses are the direct result of physical changes accompanying loss of cell turgor (6) while other responses could be due to altered levels of plant growth regulators. Plants exposed to water-limited conditions have been shown to have elevated levels of ABA (25) and ethylene (2) and reduced amounts of cytokinin (16) and gibberellin (1).…”

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Reduction of Turgor Induces Rapid Changes in Leaf Translatable RNA

Guerrero

Mullet²

1988

Plant Physiol.

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MATERIALS AND METHODSThe turgor of pea (Pisum sativum) leaves was reduced by exposing excised pea shoots to a stream of 23°C air for 20 min. Poly(A)+ RNA was isolated from control and wilted shoots, translated in vitro and radiolabeled translation products separated by electrophoresis on twodimensional (isoelectric focusing-sodium dodecyl sulfate) polyacrylamide gels. This analysis showed that the levels of several poly(A)+ RNAs increased in wilted plants. Most Exposure of plants to water-limited environments can lead to leaf wilting, stomatal closure, and decreased photosynthesis (4,24). Furthermore, leaf and reproductive tissue growth and development are often inhibited in water-deficient plants (3,8). Some of these plant responses are the direct result of physical changes accompanying loss of cell turgor (6) while other responses could be due to altered levels of plant growth regulators. Plants exposed to water-limited conditions have been shown to have elevated levels of ABA (25) and ethylene (2) and reduced amounts of cytokinin (16) and gibberellin (1).In Escherichia coli, changes in turgor pressure alter the expression ofgenes in the kdp operon which is involved in K+ transport through the cell membranes (10). In Plant Growth and Treatments. Pisum sativum (Progress No. 9) was grown for 10 d at 23°C in well-watered vermiculite using a model E15 Conviron growth chamber with continuous illumination (70 ME/m2/s) for 18 h followed by 6 h of darkness.Plant shoots (stems plus leaves) were cut, and the stem base was quickly submerged under water where a portion of the lower stem was excised. Each shoot was placed in a 0.5 ml microfuge tube containing 10 mM Hepes-KOH (pH 8.0) for 1 h pretreatment with illumination at 23°C. Shoots to be wilted were removed after pretreatment, weighed then wilted in darkness under a stream of air (23°C) for approximately 20 min until a 10 to 15% loss of fresh weight occurred. Wilted shoots were then incubated in a dark humid chamber for 0, 0.5, 1, 2, or 4 h prior to ABA assays and poly(A)+ RNA isolation. For heat shock treatment, shoots were excised, placed in Hepes-pretreatment solution and treated for 1 h in the dark at 38°C. Stems were kept submerged to help prevent shoot dehydration and any wilted shoots were discarded. Shoots used for examining the effects of exogenous ABA were excised as above and placed in solutions of 10 mM Hepes-KOH (pH 8.0) which contained 18 gM (±) ABA. Shoots were treated for 1 or 4 h in the dark at 23°C.ABA Assays. Plants were assayed for ABA content as previously reported (12). This involves extraction of 1 to 2 g fresh weight plant material in acetone:acetic acid (99:1; v/v) followed by sample cleanup by partitioning in ether at high and low pH and C18 reversed phase HPLC. ABA was quantified by Si column HPLC with a detection limit of approximately 4 pmol.Poly(A)+ RNA Isolation. Nucleic acids were isolated by phenol extraction and lithium chloride precipitation. Ten g of plant shoots were frozen in liquid N2 and ground to a powder. Thir...

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“…In soybean, Lindoo and Nooden (1 1) suggested that leaf senescence begins when leaves turn yellow. In other species, the onset of the senescence process had also been characterized by leaf yellowing (1,3,9). Sinclair and deWit (21) This investigation was conducted to study the leaf senescence processes in field-grown soybean.…”

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Leaf Senescence and Abscisic Acid in Leaves of Field-grown Soybean

Samet¹,

Sinclair²

1980

Plant Physiol.

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Leaf senescence in field-grown soybean (Merrill) as defined by the period after full expansion, was studied by measuring abscisic acid (ABA), total soluble protein, and chlorophyll in leaves through the later part of the growing season. ABA concentrations increased significantly at the end of the season when leaves had started to turn yellow, well after total soluble protein and chlorophyll had started to decline. The results indicate that events occurring before leaf yellowing are more significant in evaluating leaf senescence since the yellowing condition and rise in ABA are effects of changes in physiological activity beginning when leaves are still green. Leaf senescence is an integral part of plant development, generally including a breakdown of protein, a decrease in Chl content, changes in RNA levels, and alterations of membranes and organ-elles (4). In soybean, Lindoo and Nooden (1 1) suggested that leaf senescence begins when leaves turn yellow. In other species, the onset of the senescence process had also been characterized by leaf yellowing (1, 3, 9). Sinclair and deWit (21) hypothesized that leaf senescence in soybean is a result of the movement of materials from the leaves to developing seeds. The importance of sink demand by the developing seed as a contributor to leaf senescence should not be overlooked. This oversight may result, especially if yellowing is used as an indicator of senescence, because leaf yellowing occurs at the final stage of seed development when the accumulation of nutrients in the seeds is probably complete (15). Thomas and Stoddart (23) presented findings that question the validity of color changes as an indicator of leaf senescence. They reported on a mutant genotype of meadow fescue (Festuca praten-sis L.) that does not exhibit the characteristic yellowing of a normal genotype. Protein content, however, is reduced. Soybean desinking treatments of Mondal et al. (14) suggest that Chl loss does not necessarily indicate physiological function. Photosyn-thesis declined in both yellowing control leaves and green leaves from desinked plants. Here, leaf senescence is defined as the period after full expansion when declines in physiological activity can be observed. By this definition, the decline in photosynthesis that comes with leaf age should be considered a part of the leaf senescence process, especially as these reductions might influence ultimate yield. Evidence suggests that plant hormones are involved in leaf senescence. Investigations reveal that changes in hormonal concentrations may regulate the speed of the leaf aging process (4). ' Present address: United States There have been conflicting reports on the involvement of ABA in senescence. Lindoo and Nooden (12) and Oritani and Yoshida (16) have reported increases in ABA-like activity with senescence in leaves of field-grown soybean. Ciha et al. (7) did not find increases in ABA in leaves from field-grown soybean plants at the end of the growing season. Other investigators have found increases in ABA with leaf senescenc...

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Endogenous Gibberellin and Abscisic Acid Content as Related to Senescence of Detached Lettuce Leaves

Cited by 59 publications

References 21 publications

Antisense Inhibition of the 2-Oxoglutarate Dehydrogenase Complex in Tomato Demonstrates Its Importance for Plant Respiration and during Leaf Senescence and Fruit Maturation

Antisense Inhibition of the 2-Oxoglutarate Dehydrogenase Complex in Tomato Demonstrates Its Importance for Plant Respiration and during Leaf Senescence and Fruit Maturation

Reduction of Turgor Induces Rapid Changes in Leaf Translatable RNA

Leaf Senescence and Abscisic Acid in Leaves of Field-grown Soybean

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