Cell Cycle Progression in the Pericycle Is Not Sufficient for SOLITARY ROOT/IAA14-Mediated Lateral Root Initiation inArabidopsis thaliana

The authors responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors are: Hidehiro Fukaki and Tom Beeckman

Steffen Vanneste; Bert De Rybel; Gerrit T.S. Beemster; Karin Ljung; Ive De Smet; Gert Van Isterdael; Mirande Naudts; Ryusuke Iida; Wilhelm Gruissem; Masao Tasaka; Dirk Inzé; Hidehiro Fukaki; Tom Beeckman


Scholarcy highlights

  • Auxins have long been put forward as potent stimulators of cell division, but considerable progress has been made in our understanding of both auxin signaling and cell cycle progression, the molecular mechanisms by which these processes are connected remain poorly understood
  • PLT1 expression remained low in CYCD3;1OE 3 slr1 roots. These results indicate that the requirements for organogenetic processes, such as lateral root initiation, are more complex than simple activation of the cell cycle and that additional SLR/IAA14-dependent signaling is needed to develop a new organ
  • When the auxin-induced transcriptional changes in root segments of the wild type and slr1 are compared, the inhibition of auxin signal transduction in the mutant is correlated with the failure to induce cell cycle–related genes
  • The role of auxin in cell cycle progression is generally accepted, we found evidence that this stimulation may occur via an auxin/indole-3-acetic acid-auxin response factors– dependent pathway
  • Because AUX/IAA proteins are regarded as labile repressors, it is tempting to consider CYCA2;4 and CDKB2;1 to be primary targets of the SLR/IAA14 signaling
  • Gray marks no significant difference in induction rates between both genotypes, whereas red and orange and green and blue indicate that the induction rates are higher and lower in the wild type than in slr1, respectively
  • These results are indicative for a potential molecular mechanism by which auxin signaling may feed into the cell cycle
  • The downregulation of IAA biosynthesis genes and the upregulation of the IAA conjugation potential in early stages of lateral root initiation suggest that young primordia depend on auxin import for their development

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