Ectopic expression of the transcription factor CUC2 restricts growth by cell cycle inhibition inArabidopsisleaves

Abstract

Plant leaf margins produce small outgrowths or teeth causing serration in a regular arrangement, which is specified by auxin maxima. In Arabidopsis, the spatiotemporal pattern of auxin dependents on both, the transcription factor CUC2 and the signal peptide EPFL2, a ligand of the growth-promoting receptor kinase ERECTA (ER). Ectopic expression of CUC2 can have contrary effects on leaf growth. Ubiquitous expressed CUC2 suppresses growth in the whole leaf, whereas cuc2-1D mutants have enlarged leaves, through ER-dependent cell proliferation in the teeth. Here we investigated the growth dynamics of cuc2-1D leaves and the growth restricting the function of CUC2 using the ubiquitous inducible CUC2-GR transgene. In time courses, we dissected the serration promoting the function of CUC2 in the leaf margin and ectopic growth inhibition by CUC2 in the leaf plate. We found that CUC2 limits growth rather by cell cycle inhibition than by cell size control. Furthermore, endogenous CUC2 was rapidly induced by CUC2-GR indicating a possible auto-inducible feedback. In contrast, EPFL2 was quickly decreased by transient CUC2 induction but increased in cuc2-3 mutant leaves suggesting that CUC2 can also counteract the EPFL2-ER pathway. Therefore, tooth growth promotion and growth inhibition by CUC2 involve partially the same mechanism but in contrary ways.

An Artificial Conversion of Roots into Organs with Shoot Stem Characteristics by Inducing Two Transcription Factors

“…The inconsistency might be explained by the lack of ectopic expression of the WUS in the meristematic cells even when the ATHB25/REM7 is activated, as the WUS functions in meristems ( Gallois et al., 2004 ). It was also inconsistent with the previous reports describing that overexpression or ectopic induction of the CUC genes ( CUC -ox) deepened serration of cotyledon and leaf margins but did not exhibit the cuc -like phenotypes ( Li et al., 2020 ; Nikovics et al., 2006 ; Takada et al., 2001 ), that the ATHB25/REM7-ox F1 plants display the unseparated cotyledon as seen in the phenotype of the cuc mutant ( Aida et al., 1997 ). It seems that the ATHB25/REM7 acts not only on the expression of the CUC genes and subsequent expression of WUS but also on an unknown function that works to maintain the SAM properly.…”

The epigenetic regulator ULTRAPETALA1 suppresses de novo root regeneration from Arabidopsis leaf explants

“…With the exception of ABI3 ( N = 3), all expression data represent four biological replicates. Total RNA preparation, cDNA synthesis, and real-time RT-qPCR including ABI3 21 , SPL2 22 , SPL10 23 , SPL11 22 , SPL15 22 , ERF109 11 , ABR1 11 , ASA1 11 , YUC2 9 , YUC6 , 23 and eIF4A primers 24 , 25 have been previously described. 24 , 26 Furthermore, we used primers 5ʹ-GACAAATTAAAGTGACGCAAGCC-3ʹ and 5ʹ- GTTCCCGAAAGTCCTCTTCTC-3ʹ for YUC4 in the gene expression analysis.…”

Leaf growth – complex regulation of a seemingly simple process

“…Whereas cuc2 loss‐of‐function mutants display leaves with less pronounced or even without serrations, plants carrying the degradation‐resistant cuc2‐2D allele overall show bigger leaves with more pronounced serrations. Meanwhile, ectopic induction of a CUC2‐glucocorticoid receptor fusion construct leads to overall smaller leaves, suggesting overall negative effects of CUC2 on cell division (Hasson et al., 2011; Li, Zheng, et al., 2020; Sieber et al., 2007). Similarly, CUC3 maintains leaf serration by negatively regulating cell division, although no drastic leaf phenotypes have been described (Hasson et al., 2011; Serra & Perrot‐Rechenmann, 2020).…”