Leaf expansion in Arabidopsis is controlled by a TCP‐NGA regulatory module likely conserved in distantly related species

Abstract

The NGATHA (NGA) clade of transcription factors (TFs) forms a small subfamily of four members in Arabidopsis thaliana. NGA genes act redundantly to direct the development of apical tissues in the gynoecium, where they have been shown to be essential for style and stigma specification. In addition, NGA genes have a more general role in controlling lateral organ growth. The four NGA genes in Arabidopsis are expressed in very similar domains, although little is known about the nature of their putative regulators. Here, we have identified a conserved region within the four NGA promoters that we have used as a bait to screen a yeast library, aiming to identify such NGA regulators. Three members of the TCP family of TFs, named after the founding factors TEOSINTE BRANCHED 1, CYCLOIDEA and PROLIFERATING CELL FACTOR 1 AND 2), were recovered from this screening, of which two [TCP2 and TCP3, members of the CINCINNATA (CIN) family of TCP genes (CIN-TCP) subclade] were shown to activate the NGA3 promoter in planta. We provide evidence that support that CIN-TCP genes are true regulators of NGA gene expression, and that part of the CIN-TCP role in leaf development is mediated by NGA upregulation. Moreover, we have found that this TCP-NGA regulatory interaction is likely conserved in angiosperms, including important crop species, for which the regulation of leaf development is a target for biotechnological improvement.

Roles of miR319 and TCP Transcription Factors in Leaf Development

“…With respect to the downstream network that includes CUC genes, TCP transcription factors directly regulate genes related to the functions of miRNA, differentiation, cell cycling, and plant hormones ( Fig. 8A; Schommer et al, 2008Schommer et al, , 2014Koyama et al, 2010;Rodriguez et al, 2010;Efroni et al, 2013;Danisman et al, 2013;Rubio-Somoza and Weigel, 2013;Ballester et al, 2015;Challa et al, 2016). (Koyama et al, 2007), tcp4-d (Palatnik et al, 2007this work), and tcp3/4/10, tcp3/4/5/10, tcp3/4/5/10/13 (Koyama et al, 2010).…”

Evolution and Expression Patterns of TCP Genes in Asparagales

“…AtTCP4 also controls leaf senescence, maintains petal growth, and regulates early embryo development and seed viability, and finally it regulates jasmonic acid (JA) biosynthesis by the activation of LIPOXIGENASE2 (LOX2) (Schommer et al, 2008; Nag et al, 2009; Sarvepalli and Nath, 2011; Danisman et al, 2012). Leaf patterning is also controlled by CIN-like homologs in tomato and rice (Ori et al, 2007; Yang et al, 2013; Zhou et al, 2013; Ballester et al, 2015). …”

TCP factors: new kids on the signaling block

“…In flowers, ARF6 and ARF8 promote organ maturation specially of petals and anthers, thus TCP activity antagonizes flower maturation progression [29 ]. Finally, TCP2 and TCP3 bind the promoters and control leaf expression of NGATHA (NGA) genes [72 ] reported to positively regulate auxin synthesis and response [72 ,73]. All these interactions can cause local yet profound alterations in auxin signaling in addition to those related to the direct control of auxin-related genes.…”