Auxin effectively induces the formation of the secondary abscission zone in Bryophyllum calycinum Salisb. (Crassulaceae)

Marian Saniewski,Kensuke Miyamoto,Eleonora Gabryszewska,Junichi Ueda,Justyna Góraj-Koniarska

doi:10.5586/aa.1660

Marian Saniewski, Kensuke Miyamoto + Show 3 more

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https://doi.org/10.5586/aa.1660

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Abstract

We have found that auxin, indole-3-acetic acid (IAA) substantially induces the formation of the secondary abscission zone in stem and petiole explants and in decapitated stem and petiole after excision of blade in intact plants of <em>Bryophyllum calycinum</em> when IAA at a concentration of 0.1% as lanolin paste was applied in the middle of these organs. The secondary abscission zone was formed at a few mm above of the treatment with IAA, and senescence of the part above abscission zone was observed. IAA additionally applied on the top of explants or top of the dacapitated stem or the debladed petiole totally prevented the secondary abscission zone formation and senescence induced by IAA applied in the middle of these organs. Possible mechanisms of the formation of the secondary abscission zone are discussed in terms of the interaction of auxin and ethylene.

Highlights

Abscission is commonly associated with the sequence of processes resulting in shedding of multicellular organs including leaves, flowers, and fruits
We have found that auxin substantially induces the formation of the secondary abscission zone in stem and petiole explants and in decapitated stem and petiole after excision of blade of intact plants of Bryophyllum calycinum when only auxin was applied in the middle of these organs as a lanolin paste
After decapitation of apical part of shoot in naturally growing Bryophyllum calycinum morphological changes were not observed in the last internode but axillary buds were developed at base of leaves of the internode

Summary

Introduction

Abscission is commonly associated with the sequence of processes resulting in shedding of multicellular organs including leaves, flowers, and fruits. An additional abscission (the secondary abscission) zone has been known to be formed by some signals as possessing a specific functional competence between their neighboring cells, which is defined as transdifferentiation [1,2,3]. Most commonly secondary abscission occurs across the blade of a leaf, a pedicel or internode [9,14,15]. Specific protein determinants have been identified in leaf abscission cells that are preferentially expressed compared with neighboring (nonabscission) tissue [16,17,18,19]. This might be related to the mechanism of the secondary abscission zone formation

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