Peroxidase Activity in the Abscission Zone of Bean Leaves during Abscission

Poovaiah, B. W.; Rasmussen, H. P.

doi:10.1104/pp.52.3.263

Cited by 18 publications

(9 citation statements)

References 26 publications

(27 reference statements)

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“…, 2003) from superoxide anion and hydrogen peroxide. Indeed, debalding bean leaves showed an increase in peroxidase (Poovaiah and Rasmussen, 1973), and in our system decapitated poinsettia flower pedicels also revealed peroxidase in the distal area (data not shown). Such peroxidases can produce high amounts of •OH, leading to pectic polysaccharide cleavage, and may be involved in cell wall alterations in the distal cells.…”

Section: Discussionmentioning

confidence: 47%

Sequential cell wall transformations in response to the induction of a pedicel abscission event in Euphorbia pulcherrima (poinsettia)

et al. 2008

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SummaryAlterations in the detection of cell wall polysaccharides during an induced abscission event in the pedicel of Euphorbia pulcherrima (poinsettia) have been determined using monoclonal antibodies and Fourier transform infrared (FT-IR) microspectroscopy. Concurrent with the appearance of a morphologically distinct abscission zone (AZ) on day 5 after induction, a reduction in the detection of the LM5 (1 fi 4)-b-D-galactan and LM6 (1 fi 5)-a-L-arabinan epitopes in AZ cell walls was observed. Prior to AZ activation, a loss of the (1 fi 4)-b-Dgalactan and (1 fi 5)-a-L-arabinan epitopes was detected in cell walls distal to the AZ, i.e. in the to-be-shed organ. The earliest detected change, on day 2 after induction, was a specific loss of the LM5 (1 fi 4)-b-Dgalactan epitope from epidermal cells distal to the region where the AZ would form. Such alteration in the cell walls was an early, pre-AZ activation event. An AZ-associated de-esterification of homogalacturonan (HG) was detected in the AZ and distal area on day 7 after induction. The FT-IR analysis indicated that lignin and xylan were abundant in the AZ and that lower levels of cellulose, arabinose and pectin were present. Xylan and xyloglucan epitopes were detected in the cell walls of both the AZ and also the primary cell walls of the distal region at a late stage of the abscission process, on day 7 after induction. These observations indicate that the induction of an abscission event results in a temporal sequence of cell wall modifications involving the spatially regulated loss, appearance and/or remodelling of distinct sets of cell wall polymers.

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Section: Discussionmentioning

confidence: 47%

Sequential cell wall transformations in response to the induction of a pedicel abscission event in Euphorbia pulcherrima (poinsettia)

et al. 2008

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“…This effect coupled with an ethylenemediated auxin transport inhibition in the petiole quickly drops the concentration of the auxin at the abscission zone to a point where the cells in this region become responsive to the gas in terms of enzyme induction (2,23,34) and secretion (5), leading to leaf drop. All of these ethylene-mediated processes are readily reversible since the removal of ethylene at any time up to the time of actual cell separation halts the abscission process (9,17).…”

Section: Resultsmentioning

confidence: 99%

“…This is not too surprising since the localized application of potent auxin transport inhibitors to the petiole also does not trigger abscission in the absence of applied ethylene. Presumably, there is a lack of abscission under these conditions because there is insufficient ethylene at the abscission zone to trigger enzyme induction (2,23,34) and secretion (5). This view is supported by the observation that the sensitivity of leaves to ethylene is increased by pretreating only the leaf blade with ethylene.…”

Section: Resultsmentioning

confidence: 99%

“…Auxin and ethylene are without doubt two of the more important regulatory agents involved in the natural control of abscission (3, 25,32 concept that the ability of ethylene to initiate cell separation in the abscission zone through enzyme induction (2,4,23,34) and secretion (5) depends largely upon the sensitivity of this tissue to ethylene (1,3,16). The principal factor governing this sensitivity to ethylene seems certainly to be auxin.…”

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confidence: 99%

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Abscission: The Initial Effect of Ethylene Is in the Leaf Blade

Beyer¹

1975

Plant Physiol.

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The leaf blade of cotton (Gossy-piu7n hirsutum L. cv. Stoneville 213) was investigated as the initial site of ethylene action in abscission. Ethylene applied at 14 ul/l to intact 3-week-old plants caused abscission of the third true leaf within 3 days. However, keeping only the leaf blade of this leaf in air during ethylene treatment of the rest of the plant completely prevented its abscission for up to 7 days. This inhibition of abscission was apparently the result of continued auxin production in the blade since (a) the application of an auxin transport inhibitor to the petiole of the air-treated leaf blade restored ethylene sensitivity to the leaf in terms of abscission; (b) repeated applications of naphthaleneacetic acid to the leaf blade of the third true leaf, when the entire plant was exposed to ethylene, had the same preventive effect on abscission of this leaf as keeping its leaf blade in air; and (c) the inhibitory effect of ethylene on auxin transport in the petiole, which is reduced by auxin treatment, was also reduced by placing the leaf blade in air.The reverse treatment of exposing only the leaf blade of the third true leaf to 14 ,l/l of ethylene, while the rest of the plant was kept in air, also did not cause abscission for up to 5 days. Auxin transport in the petioles of these leaves, however, was inhibited over 80% within 2 days and this effect presumably accounted for their increased sensitivity to ethylene during the subsequent exposures of the whole leaf to the gas.These results suggest that an initial and essential function of applied ethylene in abscission is to reduce the amount of auxin transported out of the leaf blade. This reduction together with the inhibitory effect of ethylene on auxin transport in the petiole reduces the auxin level at the abscission zone to a point where the cells in this region become responsive to the more direct action of the gas (e.g., enzyme induction and secretion). This sequence of events accounts for the lack of abscission unless ethylene is applied to both the leaf blade and the abscission zone.

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“…Abscission also occurs in plants exposed to external stress such as darkness and dryness (REUVENI et al 1974). Increase of peroxidase activity was often found in plant tissue during infection of higher plants by pathogens (FARKAS and STAH-MANN 1966, MARAITE 1973, MAXWELL and BATEMAN 1967, SHAW and HAW-KINS 1958 and in the abscission zone fragment of non-infected bean plants during the abscission process (POOVAIAH and RASMUSSEN 1973). Recently, we have shown that the leaf abscission of infected pepper plants may be stimulated by external administration of Mn^ , a known co-factor for peroxidase activity, and diminished by indole-3-acetic acid (IAA) or its analog, indole-3butyric acid (IBA) (REUVENI et al 1976).…”

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confidence: 99%