Analysis of Microtubule-Associated-Proteins during IBA-Mediated Adventitious Root Induction Reveals KATANIN Dependent and Independent Alterations of Expression Patterns

Mohamad Abu-Abied,Geoffrey O Wasteneys,Einat Sadot,Gujulla B Sunil Kumar,Ron Ophir,Inna Mordehaev,Abidur Rahman

doi:10.1371/journal.pone.0143828

Mohamad Abu-Abied, Geoffrey O Wasteneys + Show 5 more

Open Access

https://doi.org/10.1371/journal.pone.0143828

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Abstract

Adventitious roots (AR) are post embryonic lateral organs that differentiate from non-root tissues. The understanding of the molecular mechanism which underlies their differentiation is important because of their central role in vegetative plant propagation. Here it was studied how the expression of different microtubule (MT)-associated proteins (MAPs) is affected during AR induction, and whether expression differences are dependent on MT organization itself. To examine AR formation when MTs are disturbed we used two mutants in the MT severing protein KATANIN. It was found that rate and number of AR primordium formed following IBA induction for three days was reduced in bot1-1 and bot1-7 plants. The reduced capacity to form ARs in bot1-1 was associated with altered expression of MAP-encoding genes along AR induction. While the expression of MAP65-4, MAP65-3, AURORA1, AURORA2 and TANGLED, increased in wild-type but not in bot1-1 plants, the expression of MAP65-8 and MDP25 decreased in wild type plants but not in the bot1-1 plant after two days of IBA-treatment. The expression of MOR1 was increased two days after AR induction in wild type and bot1-1 plants. To examine its expression specifically in AR primordium, MOR1 upstream regulatory sequence was isolated and cloned to regulate GFP. Expression of GFP was induced in the primary root tips and lateral roots, in the pericycle of the hypocotyls and in all stages of AR primordium formation. It is concluded that the expression of MAPs is regulated along AR induction and that reduction in KATANIN expression inhibits AR formation and indirectly influences the specific expression of some MAPs.

Highlights

Adventitious roots (AR) are roots that differentiate from non-root tissues, as a response to endogenous or exogenous auxin signaling [1]
The latter is highly relevant to AR formation because like lateral roots (LRs), AR are differentiated from inner layers perceiving mechanical signaling from the upper layers above them
We examined to what extent the reduction of KATANIN expression affects AR formation in cut etiolated hypocotyls treated with IBA

Summary

Introduction

ARs are roots that differentiate from non-root tissues, as a response to endogenous or exogenous auxin signaling [1]. KATANIN is a MT severing protein that is involved with MT responses to ROP GTPase signaling [9], auxin signaling [11], blue light [12] and mechanical signaling [13] The latter is highly relevant to AR formation because like LR, AR are differentiated from inner layers perceiving mechanical signaling from the upper layers above them. It has been shown that inhibition of cell layer separation above the LR primordium by suppressing auxin signaling in these layers or by suppressing INFLORESCENCE DEFICIENT IN ABSCISSION (IDA) abscission signaling affects LR primordium morphogenesis and differentiation [14, 16, 17] These studies suggest that the pressure exerted by the upper layers needs to be gradually reduced during induction, to allow root emergence, and proper LR differentiation. The influence of KATANIN on AR formation was further studied here

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