CFLAP1 and CFLAP2 Are Two bHLH Transcription Factors Participating in Synergistic Regulation of AtCFL1-Mediated Cuticle Development in Arabidopsis

Abstract

The cuticle is a hydrophobic lipid layer covering the epidermal cells of terrestrial plants. Although many genes involved in Arabidopsis cuticle development have been identified, the transcriptional regulation of these genes is largely unknown. Previously, we demonstrated that AtCFL1 negatively regulates cuticle development by interacting with the HD-ZIP IV transcription factor HDG1. Here, we report that two bHLH transcription factors, AtCFL1 associated protein 1 (CFLAP1) and CFLAP2, are also involved in AtCFL1-mediated regulation of cuticle development. CFLAP1 and CFLAP2 interact with AtCFL1 both in vitro and in vivo. Overexpression of either CFLAP1 or CFLAP2 led to expressional changes of genes involved in fatty acids, cutin and wax biosynthesis pathways and caused multiple cuticle defective phenotypes such as organ fusion, breakage of the cuticle layer and decreased epicuticular wax crystal loading. Functional inactivation of CFLAP1 and CFLAP2 by chimeric repression technology caused opposite phenotypes to the CFLAP1 overexpressor plants. Interestingly, we find that, similar to the transcription factor HDG1, the function of CFLAP1 in cuticle development is dependent on the presence of AtCFL1. Furthermore, both HDG1 and CFLAP1/2 interact with the same C-terminal C4 zinc finger domain of AtCFL1, a domain that is essential for AtCFL1 function. These results suggest that AtCFL1 may serve as a master regulator in the transcriptional regulation of cuticle development, and that CFLAP1 and CFLAP2 are involved in the AtCFL1-mediated regulation pathway, probably through competing with HDG1 to bind to AtCFL1.

GCN5 contributes to stem cuticular wax biosynthesis by histone acetylation of CER3 in Arabidopsis

“…Consistent with previous studies ( Haslam et al , 2015 ; Lee and Suh, 2015 ; Li et al , 2016 ), the content of the unidentified components (which showed no significant differences among genotypes) was excluded from the total wax load.…”

“…Plant cuticular wax is a complex mixture of very-long-chain fatty acids (VLCFAs) and aldehydes, alcohols, alkanes, ketones, and esters, with predominant carbon chain-lengths ranging from C22 to C36 ( Samuels et al , 2008 ; Li et al , 2016 ), and it forms one of the major lipid components of the cuticle that covers the outer surface of aerial plant tissues. The biosynthesis of cuticular wax is processed through two distinct pathways, termed the alcohol-forming and the alkane-forming pathways, which yield 17~18% and 80% of the total amount of wax, respectively ( Bernard and Joubès, 2013 ).…”

Cuticle Structure in Relation to Chemical Composition: Re-assessing the Prevailing Model

“…Several studies used Arabidopsis thaliana (L) Heynh as model for cutin biosynthesis (e.g., Nawrath et al, 2013 ; Go et al, 2014 ; Fabre et al, 2016 ; Li et al, 2016 ), but its cuticle composition is atypical and not representative for most plant species ( Franke et al, 2005 ; Pollard et al, 2008 ; Domínguez et al, 2011 ). Due to the increased availability of tomato ( Solanum lycopersicum L.) genomic resources, this fruit is also being used as model for analyzing the mechanisms of cuticle formation (e.g., Martin and Rose, 2014 ; Petit et al, 2014 ).…”

Fine mapping of an up-curling leaf locus (BnUC1) in Brassica napus

“…CFLAP2 interacts with the C-terminal of CFL1 to regulate the downstream genes BODYGUARD ( BDG ) and FIDDLEHEAD ( FDH ), and negatively regulate cuticle development. When CFL1 or CFLAP2 is overexpressed, the expression of BDG and FDH are negatively regulated to decrease cuticle density, leading to defective cuticle development, which affects the differentiation of epidermal cells and changes the status of epidermal cells [43]. In the curly flag leaf 1 rice mutant, overexpression of CFL1 down-regulated the expression of BDG and FDH , which affected the development of leaf cuticle and led to the curly flag leaf phenotype [44].…”