Further Comparative Studies of Pectin Esterase in Relation to Leaf and Flower Abscission

Moline, H. E.; LaMotte, Clifford E.; Gochnauer, Carl; McNamer, Alan Dale

doi:10.1104/pp.50.6.655

Cited by 23 publications

(12 citation statements)

References 10 publications

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“…Although her findings were supported by LaMotte et al (6), several other studies reported no change in PE activity over the course of abscission in Nicotiana (25), Phaseolus (9,18,19), and Citrus (21).…”

supporting

confidence: 70%

“…Moline et al (9) were able to detect a change in PE levels in Coleus, but not in nine other plants. These observations suggest that although PE may play a role in abscission in certain plants, the involvement of this enzyme in a general abscission mechanism is questionable.…”

mentioning

confidence: 99%

“…These findings suggest the possible role of pectolytic enzymes in the dissolution of the middle lamella during abscission. Studies on the role of pectinesterase (6,9,11,(18)(19)(20)(21) 25) and polygalacturonase (1,2,5,10,(17)(18)(19)22) The present paper reexamines the role of PG in the abscission of leaves of Phaseolus using recent techniques (16,22) for extracting the enzyme and measuring activity. The results show that PG is localized in the abscission zone, although changes in enzyme activity were not found to accompany abscission.…”

mentioning

confidence: 99%

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Role of Polygalacturonase in Bean Leaf Abscission

Berger

Reid²

1979

Plant Physiol.

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The role of polygalacturonase in leaf abscission was studied in explants of Phaseols vudgaris L. cv. Red Kidley. Bean polygalacturonase was partiafly characterized and comparisons were made between the bean enzyme and previously reported higher plant polygalacturonases. Polygalacturonase isolated from bean leaf abscission zones has a pH optimum between 4.5 and 5.0 and hydrolyzed polygalacturonides in an exo-fashion.Activity was found to be higher with a deesterified substrate than with an esterifled pectin. No correlation between polygalacturonase activity and abscission was observed. Activity remained virtuafly constant over the course of abscission in explants aged either in air or in ethylene. The enzyme was primarily localized in the abscission zone, however, indicating a possible involvement in the abscission process. A theoretical model which could explain the relationship between polygalacturonase and bean leaf abscission is discussed.An increase in soluble pectins of the middle lamella in abscising tissue has been reported in several studies (3,10,(23)(24)(25). These findings suggest the possible role of pectolytic enzymes in the dissolution of the middle lamella during abscission. Studies on the role of pectinesterase (6,9,11,(18)(19)(20)(21) 25) and polygalacturonase (1,2,5,10,(17)(18)(19)22) The present paper reexamines the role of PG in the abscission of leaves of Phaseolus using recent techniques (16,22) for extracting the enzyme and measuring activity. The results show that PG is localized in the abscission zone, although changes in enzyme activity were not found to accompany abscission. MATERIALS AND METHODSPlant Material and Treatments. Seeds of Phaseolus vulgaris L. cv. Red Kidney were sown in flats of Vermiculite. The flats were kept in growth chambers programed for a 16-h photoperiod at 1,000 ft-c with a 28 C day temperature and a 26 C night temperature. The flats were watered every other day or when surface Vermiculite became dry. Seedlings were harvested when the primary leaves were fully expanded, usually 9 to 10 days after sowing. The cotyledons, leaf blades, and shoot apex were excised and the explants were placed in beakers filled with distilled H20. The beakers were left to sit either in air or in a desiccator injected with 50,u/ll ethylene.Extraction of Enzyme. Abscission zones were sliced from explants so that equal lengths of pulvinus and petiole surrounded the separation layer, making a total segment length of approximately 4 mm. In certain experiments which were conducted to determine enzyme localization, sections of petiole were used in place of abscission zones. For each replication of an experiment, 60 zones were weighed and ground in mortar and pestle with sea sand and 10 ml of 50 mm Na-phosphate buffer (pH 7.5) containing 6% (w/v) ammonium sulfate. Subsequent steps were carried out in an ice bath or under refrigeration using a modification of the method described by Riov (22).In the modified procedure, the ground homogenate was stirred for 30 min and filtered through f...

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supporting

confidence: 70%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Role of Polygalacturonase in Bean Leaf Abscission

Berger

Reid²

1979

Plant Physiol.

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“…The physiological evidence indicates role of both PG and PME in cell wall dissolution (Van Doorn and Stead 1997) and its de novo synthesis (Lohani et al 2004). In tobacco flower abscission zone, no change was found in PME activity (Moline et al 1972) but PG activity increased (Tucker et al 1984). A gene for PG has been isolated from tomato flower pedicle absicission zone, which was regulated in co-ordination with flower absicission (Kalaitzis et al 1995).…”

Section: Cell Wall Metabolismmentioning

confidence: 98%

Flower bud opening and senescence in roses (Rosa hybrida L.)

2008

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The flower is the most significant and beautiful part of plants. Flowers are very useful organs in plant developmental phenomenon. During flower bud opening, various events takes place in a well defined sequence, representing all aspects of plant development, such as cell division, cellular differentiation, cell elongation or expansion and a wide spectrum of gene expression. The complexity of flower bud opening illustrates that various biological mechanisms are involved at different stages. Senescence represents the ultimate stage of floral development and results in wilting or abscission of whole flower or flower parts. Senescence is an active process and governed by a well defined cell death program. Once a flower bud opens, the programmed senescence of petal allows the removal of a metabolically active tissue. In leaves, this process can be reversed, but in floral tissue it cannot, indicating that a highly controlled genetic program for cell death is operating. The termination of a flower involves at least two, sometimes overlapping, mechanisms. In one, the perianth abscises before the majority of its cells initiate a cell death program. Abscission may occur before or during the mobilization of food reserves to other parts of the plant. Alternatively, the petals may be more persistent, so that cell deterioration and food remobilization occur while the petals are still part of the flower. The overall pattern of floral opening varies widely between plant genera, therefore, a number of senescence parameters have been used to group plants into somewhat arbitrary categories. Opening and senescence of rose flower is still an unsolved jigsaw in the world of floriculture industry and the mechanism behind the onset of the very early events in the sequence still remains to be elucidated. Hence, for advancing the knowledge on the pertinent aspect of bud opening and senescence the literature has been cited under this review.Keywords Abscisic acid Á Ascorbate peroxidase Á Catalase Á Ethylene Á Gibberellin Á Glutathione reductase Á Hydrogen peroxide Á Hydroxyl radical Á Lipoxygenase Á Pectin methyl esterase Á Polygalactouronase Á Peroxidase Á Relative water content Plant growths regulators Gibberellins (GAs)The role of GAs in petal growth has been demonstrated in many plants. Analysis of endogenous GAs in young petunia anthers and corolla indicated the

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“…S4B), so it is likely that the protein product from this gene may be secreted. Although a role for pectin esterases in abscission was first proposed over 50 years ago (Osborne, 1958), the evidence remains conflicting (Yager, 1960;LaMotte et al, 1969;Ratner et al, 1969;Moline et al, 1972;Roberts and González-Carranza, 2009). In Arabidopsis, it has been demonstrated that three of at least 59 putative pectin esterase genes in Arabidopsis are up-regulated during floral organ abscission (Cai and Lashbrook, 2008).…”

Section: Proposed Roles For the Abscission-related Genes Identifiedmentioning

confidence: 99%

A Novel Approach to Dissect the Abscission Process in Arabidopsis

et al. 2012

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Abscission is the consequence of a specialized layer of cells undergoing a complex series of molecular and biochemical events. Analysis of the specific molecular changes associated with abscission is hampered by contamination from neighboring nonseparating tissues. Moreover, studies of abscission frequently involve the examination of events that take place in isolated segments of tissue exposed to nonphysiological concentrations of ethylene or indole-3-acetic acid for protracted periods (more than 24 h) of time. To resolve these problems, we have adopted the use of a transgenic line of Arabidopsis (Arabidopsis thaliana) where the promoter of an abscission-specific polygalacturonase gene (At2g41850/ARABIDOPSIS DEHISCENCE ZONE POLYGALACTURONASE2) has been fused to a green fluorescent protein reporter. RNA was extracted from green fluorescent protein-tagged cells, released from abscising floral organs, and used to generate a complementary DNA library. This library was used to probe a microarray, and a population of abscission-related transcripts was studied in detail. Seven novel abscission-related genes were identified, four of which encode proteins of unknown function. Reverse transcription-polymerase chain reaction analyses and promoter fusions to the b-glucuronidase reporter gene confirmed the expression of these genes in the abscission zone and revealed other places of expression during seedling development. Three of these genes were studied further by crossing reporter lines to the abscission mutants inflorescence deficient in abscission (ida) and blade-on-petiole1 (bop1)/bop2 and an IDA-overexpressing line. Phenotypic analysis of an At3g14380 transfer DNA insertion line indicates that this gene plays a functional role in floral organ shedding. This strategy has enabled us to uncover new genes involved in abscission, and their possible contribution to the process is discussed.

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Further Comparative Studies of Pectin Esterase in Relation to Leaf and Flower Abscission

Cited by 23 publications

References 10 publications

Role of Polygalacturonase in Bean Leaf Abscission

Role of Polygalacturonase in Bean Leaf Abscission

Flower bud opening and senescence in roses (Rosa hybrida L.)

A Novel Approach to Dissect the Abscission Process in Arabidopsis

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