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Research article2015Peer reviewedOpen access

Auxin is a long-range signal that acts independently of ethylene signaling on leaf abscission in Populus

Jin, Xu; Zimmermann, Jorma; Polle, Andrea; Fischer, Urs

Abstract

Timing of leaf abscission is an important trait for biomass production and seasonal acclimation in deciduous trees. The signaling leading to organ separation, from the external cue (decreasing photoperiod) to ethylene-regulated hydrolysis of the middle lamellae in the abscission zone, is only poorly understood. Data from annual species indicate that the formation of an auxin gradient spanning the abscission zone regulates the timing of abscission. We established an experimental system in Populus to induce leaf shedding synchronously under controlled greenhouse conditions in order to test the function of auxin in leaf abscission. Here, we show that exogenous auxin delayed abscission of dark-induced leaves over short and long distances and that a new auxin response maximum preceded the formation of an abscission zone. Several auxin transporters were down-regulated during abscission and inhibition of polar auxin transport delayed leaf shedding. Ethylene signaling was not involved in the regulation of these auxin transporters and in the formation of an abscission zone, but was required for the expression of hydrolytic enzymes associated with cell separation. Since exogenous auxin delayed abscission in absence of ethylene signaling auxin likely acts independently of ethylene signaling on cell separation.

Keywords

Populus; auxin; ethylene; abscission; cell separation; PIN proteins

Published in

Frontiers in Plant Science
2015, volume: 6, article number: 634
Publisher: FRONTIERS MEDIA SA

SLU Authors

UKÄ Subject classification

Cell Biology

Publication identifier

  • DOI: https://doi.org/10.3389/fpls.2015.00634

Permanent link to this page (URI)

https://res.slu.se/id/publ/73925