MYB156
promotes root sucker formation by repressing
IDD14
and
CKX1
Hongying Pang, Biying Li, Yajuan Chen, Liping Ding, Wanwan Lyu, Xiaoqin Wang, Hongzhi Wang, Jianhua Wei, Lin Zheng Summary
Root suckers enable clonal propagation of rooting‐recalcitrant poplars, conferring rejuvenated traits such as enhanced survival and accelerated growth. Despite widespread clonal propagation and ecological restoration, the essential genes controlling sucker development remain unidentified.
MYB156 is a positive regulator of root sucker formation in white poplar (
Populus davidiana
×
P. bolleana
).
MYB156
is predominantly expressed in proliferation‐competent root cells, including vascular cambium and phellogen. Gain‐ and loss‐of‐function analyses demonstrated that
MYB156
overexpression enhanced root suckering and secondary growth, whereas
myb156
mutants were severely compromised in both. Meanwhile, cytokinin levels increased two‐ to fivefold in roots with
MYB156
overexpression but were significantly reduced in
myb156
mutant roots.
MYB156 directly represses
IDD14
and
CKX1
, reducing cytokinin catabolism and alleviating
IDD14
‐mediated suppression of cytokinin accumulation;
IDD14
RNAi lines similarly showed elevated cytokinin and enhanced suckering.
Cytokinin response elements in the
MYB156
promoter and MYB156 autoactivation establish a cytokinin‐MYB156 positive feedback loop amplifying cytokinin signaling in meristematic zones. Live imaging with the cytokinin response reporter
TCSn
:
RFP
demonstrated that suckering in
MYB156
‐overexpressing plants shifted from the phellogen to the vascular cambium. These findings establish a MYB156‐
CKX1
/
IDD14
‐cytokinin module that creates a permissive context for suckering, providing a transcriptional blueprint for clonal propagation.