Edinburgh, Scotland, United Kingdom - TAIR

Untangling transcriptional regulatory networks
modulating hormone responses
The phytohormone ethylene plays critical roles in growth, defense and a myriad
other plant processes by regulating the expression of large and diverse sets of
genes through control of protein stabilization of the master transcriptional
regulator EIN3. Using ChIP-Seq and RNA-Seq methods, we found that EIN3 is
involved in a feedback loop that controls both positive and negative components
in ethylene signaling. Several ethylene receptor genes are direct EIN3-binding
targets, along with genes encoding CTR1 protein kinase and EBF1/EBF2, EIN3binding
F-box proteins, EER5, a proteasome-related signalosome subunit that
is proposed to be involved resetting the ethylene-signaling pathway, as well as
RAN1 a copper transporter involved in ethylene receptor function. We also
identified a number of positive regulators in the ethylene signaling pathway
components among the list of EIN3 direct target genes. Confirming that a
massive transcriptional cascade is a critical aspect of the diverse responses
mediated by ethylene output pathways, we identified many AP2/ERF and WRKY
transcription factors as direct EIN3 binding targets; several of which are known
to be involved in mediating responses to pathogens. In addition, we identified key
points of hormone crosstalk of ethylene with other hormones. Direct EIN3 targets
included several of the master regulatory transcription factors controlling growth
regulation by other hormones, revealing new (and direct) connections among
these signaling pathways. Additional EIN3 targets include enzymes for hormone
biosynthesis or conjugation, further supporting the existence of connections
among hormone pathways. Finally, we merged the EIN3-target information with
global gene expression information and a large protein-protein interaction
network (Braun et al. CCSB-Harvard/Salk, unpublished) to establish a first
generation hormone interactome network map. As indicated by the multitude of
connections between different nodes in the network, EIN3 targets encompass
numerous hormone biosynthesis and signaling pathways which can now be
further explored.
81
C30
Thursday 14:00 - 14:30
Plant Growth Regulators
Katherine N Chang
Hong Qiao
Dwight Kuo
Trey Ideker
Joseph R Ecker
The Salk Institute
La Jolla CA
Univ. of Calif
San Diego
USA