Very-long-chain fatty acids restrict regeneration capacity by confining pericycle competence for callus formation in Arabidopsis.
The already differentiated organs in plants have a remarkable capacity to regenerate new individuals under culture conditions. Plant in vitro regeneration practically starts with the induction of a pluripotent cell mass, the callus, from detached organs on auxin-rich callus-inducing medium (CIM), which is generally required for subsequent regeneration of new bodies. Recent studies show that CIM-induced callus formation occurs from the pericycle or pericycle-like cells through a root developmental pathway, whereas the signals involved in governing callus-forming capacity of pericycle cells remain unknown. Here we report that very-long-chain fatty acids (VLCFAs) play a critical role in confining the pericycle competence for callus formation and thus the regeneration capacity of Arabidopsis By genetic screening, we identified the callus formation-related 1 (cfr1) mutant, which bypasses the inhibition of callus-forming capacity in roots by solitary-root (slr/iaa14). We show that CFR1 encodes 3-ketoacyl-CoA synthase 1 (KCS1), which catalyzes a rate-limiting step of VLCFA biosynthesis. Our biochemical and genetic analyses demonstrate that VLCFAs restrict the pericycle competence for callus formation, at least in part, by regulating the transcription of Aberrant Lateral Root Formation 4 (ALF4). Moreover, we provide evidence that VLCFAs act as cell layer signals to mediate the pericycle competence for callus formation. Taken together, our results identify VLCFAs or their derivatives as the confining signals for mediating the pericycle competence for callus formation and thus the regeneration capacity of plant organs.
Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; University of the Chinese Academy of Sciences, Beijing 100049, China;
Baoshuan
B
Shang
Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China;
Chongyi
C
Xu
Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; University of the Chinese Academy of Sciences, Beijing 100049, China;
Xixi
X
Zhang
Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; University of the Chinese Academy of Sciences, Beijing 100049, China;
Huifen
H
Cao
Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China;
Wei
W
Xin
Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; National Center for Plant Gene Research, Beijing 100093, China huyuxin@ibcas.ac.cn.
Yuxin
Y
Hu
D017360:Arabidopsis / Q000254:growth & development* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism*; D018517:Plant Roots / Q000254:growth & development* / Q000378:metabolism*
D029681:Arabidopsis Proteins; D005227:Fatty Acids
VLCFA; callus formation; pericycle; regeneration