The transport and metabolism of 14C-labelled indoleacetic acid in intact pea seedlings

Morris, David; Briant, R. E.; Thomson, Peter G.

doi:10.1007/bf00386984

Cited by 112 publications

(39 citation statements)

References 42 publications

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“…Additionally, when decarboxylation products have been detected in extracts, these products have often been viewed as resulting from experimentally induced (artifactual) exposure of auxin to peroxidases (Bandurski et al, 1995;Normanly, 1997;Ö stin et al, 1998). However, our results support a specific (non-artifactual) capacity of root tips to decarboxylate IAA, as suggested by several previous investigators (Morris et al, 1969;Bourbouloux and Bonnemain, 1974;Pernet and Pilet, 1979).…”

Section: Discussionsupporting

confidence: 82%

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Auxin Metabolism in the Root Apical Meristem

Kerk¹,

2000

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Within the root meristem of flowering plants is a group of mitotically inactive cells designated the quiescent center (QC). Recent work links the quiescent state to high levels of the growth regulator auxin that accumulates in the QC via polar transport. This in turn results in elevated levels of the enzyme ascorbic acid oxidase (AAO), resulting in a reduction of ascorbic acid (AA) within the QC and mitotic quiescence. We present evidence for additional interactions between auxin, AAO, and AA, and report that, in vitro, AAO oxidatively decarboxylates auxin, suggesting a mechanism for regulating auxin levels within the QC. We also report that oxidative decarboxylation occurs at the root tip and that an intact root cap must be present for this metabolic event to occur. Finally, we consider how interaction between auxin and AAO may influence root development by regulating the formation of the QC.

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Section: Discussionsupporting

confidence: 82%

“…It has long been known that auxin is transported from the shoot to the root in a polar manner (Scott and Wilkins, 1968;Morris et al, 1969). However, little attention has been given to the fate of the auxin accumulating in the root tip.…”

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confidence: 99%

Auxin Metabolism in the Root Apical Meristem

Kerk¹,

2000

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“…3) support earlier findings (18) that the level of free auxin in the tissue depends on the activity of the conjugation system. Results (Table II), however, do not support the assumption that NAA conjugates are storage forms (26). In fact, the in livo breakdown of conjugates to their original components was never observed.…”

Section: Discussionmentioning

confidence: 67%

“…He also proposed that only auxin found in the cytoplasm was biologically active, and that it is in equilibrium with both the auxin present in solution and that bound within the cell. However, on several occasions IAAsp has been found in plants in the absence of exogenous application of IAA (19,26,27,30,35,37). conjugates of IAA and NAA, respectively (40).…”

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Mechanism of Naphthaleneacetic Acid Conjugation

Gören¹,

Bukovac²

1973

Plant Physiol.

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Formation of naphthaleneacetic acid-glucose (NAGlu) in detached leaves, floating on a-naphthaleneacetic acid-1-V4C (NAA, 0.05 microcurie per milliliter, 3.1 ,uM)-buffer solution (phosphate-citrate, pH 4.2) began immediately while there was a 2-to 4-hour lag before NAA-asparatate (NAAsp) could be detected. Subsequent increase in the NAAsp conjugate reflected a decrease in free NAA to 1 to 2 % of the total radioactivity taken up. Pretreatment with 31 gM 'C-NAA for 18 hours doubled NAAsp formation after transfer for 4 hours to '4C-NAA. Pretreatment with ethylene, as ethephon (up to 400 milligrams per liter) or ethylene gas (10 microliters per liter), did not induce NAAsp formation. In the presence of NAA, ethylene had no effect on NAA conjugation. Similarly, CO2 (5%) did not modify the formation of the conjugates. Rhizobitoxine (1.87 uM) inhibited NAA-induced ethylene production but did not prevent NAA-induced formation of NAAsp. We concluded that the conjugation of NAA with aspartic acid is not mediated by ethylene.

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The Time‐course of Polar Movement of Gibberellin Through Zea Roots

Jacobs

Pruett

1973

American J of Botany

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The polarity of movement of gibberellin through sections cut from near the root tips of Zea mays L. was studied, using methods like those we previously used in roots for auxin and in petioles for auxins, cytokinins, and gibberellic acid (GA‐3). One μg GA‐3 was added in a donor agar block and gibberellin activity in the receiver agar at the opposite end of the section was measured directly with a modified barley endosperm bioassay. The movement of gibberellin was away from the root tip (basipetal) and thus opposite in direction to the polarity of auxin through such root sections. The time‐course of basipetal movement was dissimilar to that for gibberellin or auxin movement through petiole sections. It took 14‐18 hr for gibberellin activity equivalent to 6 ng GA‐3 to collect in the basal receivers on roots. Apical receivers showed activity equivalent to 1.6 ng GA‐3 at 14‐18 hr. Less than 0.01 ng equivalent GA‐3 was collected from sections to which GA‐3 was not added, so the 6 and 1.6 ng were almost entirely due to the added GA‐3. These general conclusions were confirmed with an experiment using 14C‐GA‐3. A decline in activity in receivers was found in some experiments at 18 hr, paralleling earlier results with GA‐3, IAA, and adenine in petioles and IAA in roots.

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The transport and metabolism of 14C-labelled indoleacetic acid in intact pea seedlings

Cited by 112 publications

References 42 publications

Auxin Metabolism in the Root Apical Meristem

Auxin Metabolism in the Root Apical Meristem

Mechanism of Naphthaleneacetic Acid Conjugation

The Time‐course of Polar Movement of Gibberellin Through Zea Roots

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