Sirtinol, a Sir2 protein inhibitor, affects stem cell maintenance and root development in Arabidopsis thaliana by modulating auxin-cytokinin signaling components

Sharmila Singh,Ananda K Sarkar,Alka Singh,Archita Singh,Sandeep Yadav,Vibhav Gautam

doi:10.1038/srep42450

Sharmila Singh, Ananda K Sarkar + Show 4 more

Open Access

https://doi.org/10.1038/srep42450

Copy DOI

Journal: Scientific Reports	Publication Date: Feb 14, 2017
Citations: 14	License type: open-access

Affiliation: National Institute of Plant Genome Research

Abstract

In Arabidopsis thaliana, besides several key transcription factors and chromatin modifiers, phytohormones auxin and cytokinin play pivotal role in shoot and root meristem maintenance, and lateral root (LR) development. Sirtinol, a chemical inhibitor of Sir2 proteins, is known to promote some auxin induced phenotypes in Arabidopsis. However, its effect on plant stem cell maintenance or organ formation remained unaddressed. Here we show that sirtinol affects meristem maintenance by altering the expression of key stem cell regulators, cell division and differentiation by modulating both auxin and cytokinin signaling in Arabidopsis thaliana. The expression of shoot stem cell niche related genes WUSCHEL (WUS) and CLAVATA3 (CLV3) was upregulated, whereas SHOOT MERISTEMLESS (STM) was downregulated in sirtinol treated seedlings. The expression level and domain of key root stem cell regulators PLETHORA (PLTs) and WUS-Related Homeobox 5 (WOX5) were altered in sirtinol treated roots. Sirtinol affects LR development by disturbing proper auxin transport and maxima formation, similar to 2,4-dichlorophenoxyacetic acid (2,4-D). Sirtinol also affects LR formation by altering cytokinin biosynthesis and signaling genes in roots. Therefore, sirtinol affects shoot and root growth, meristem maintenance and LR development by altering the expression of cytokinin-auxin signaling components, and regulators of stem cells, meristems, and LRs.

Highlights

Unlike animals, plants continuously produce new organs throughout their lifetime through the meristematic activity maintained by stem cells that reside in shoot and root apical meristems (SAM and RAM)
Whereas cytokinin activates differentiation process[17]. This antagonism of auxin and cytokinin involves a regulatory circuit, where ARABIDOPSIS RESPONSE REGULATOR 1 (ARR1) and ARR12 activate the expression of SHORT HYPOCOTYL2 (SHY2), an AUX/indole-3- acetic acid (IAA) protein, which in turn represses the expression of PINs, and in a negative feedback loop, PINs inhibit the expression of SHY217,18
These results suggest that sirtinol affects the gravitropic response of the plants, besides effect on root growth

Summary

Introduction

Plants continuously produce new organs throughout their lifetime through the meristematic activity maintained by stem cells that reside in shoot and root apical meristems (SAM and RAM). Whereas cytokinin activates differentiation process[17] This antagonism of auxin and cytokinin involves a regulatory circuit, where ARABIDOPSIS RESPONSE REGULATOR 1 (ARR1) and ARR12 activate the expression of SHORT HYPOCOTYL2 (SHY2), an AUX/IAA protein, which in turn represses the expression of PINs, and in a negative feedback loop, PINs inhibit the expression of SHY217,18. This balance of auxin and cytokinin ratio defines the RAM size, cell division and differentiation, and thereby regulate root growth. Apart from classical genetics, the chemical genetics approach uses cell permeable small molecules to disturb a gene function, similar to mutagenesis but in a rapid, reversible and conditional manner, and it has emerged as a powerful tool to study gene functions and characterize biological pathways[31,32]

Methods

Results

Conclusion