OVATE FAMILY PROTEIN4 (OFP4) interaction with KNAT7 regulates secondary cell wall formation in Arabidopsis thaliana

Abstract

SUMMARYThe homeodomain transcription factor KNAT7 has been reported to be involved in the regulation of secondary cell wall biosynthesis. Previous work suggested that KNAT7 can interact with members of the Ovate Family Protein (OFP) transcription co-regulators. However, it remains unknown whether such an OFP-KNAT7 complex could be involved in the regulation of secondary cell wall biosynthesis in Arabidopsis. We re-tested OFP1 and OFP4 for their abilities to intact with KNAT7 using yeast two-hybrid assays, and verified KNAT7-OFP4 interaction but found only weak interaction between KNAT7 and OFP1. Further, the interaction of KNAT7 with OFP4 appears to be mediated by the KNAT7 homeodomain. We used bimolecular fluorescence complementation to confirm interactions and found that OFP1 and OFP4 both interact with KNAT7 in planta. Using a protoplast transient expression system we showed that KNAT7 as well as OFP1 and OFP4 act as transcriptional repressors. Furthermore, in planta interactions between KNAT7 and both OFP1 and OFP4 enhance KNAT7's transcriptional repression activity. An ofp4 mutant exhibited similar irx and fiber cell wall phenotypes as knat7, and the phenotype of a double ofp4 knat7mutant was similar to those of the single mutants, consistent with the view that KNAT7 and OFP function in a common pathway or complex. Furthermore, the pleiotropic OFP1 and OFP4 overexpression phenotype was suppressed in a knat7 mutant background, suggesting that OFP1 and OFP4 functions depend at least partially on KNAT7 function. We propose that KNAT7 forms a functional complex with OFP proteins to regulate aspects of secondary cell wall formation.

Transcriptional, Posttranscriptional, and Posttranslational Regulation of SHOOT MERISTEMLESS Gene Expression in Arabidopsis Determines Gene Function in the Shoot Apex

“…Several members of the OVATE family of factors (AtOFPs) interact with KNOX and BELL factors, regulating their subcellular localization (Hackbusch et al, 2005). BLH1, BLH7, and KNAT1 interact with AtOFP1 (Hackbusch et al, 2005), BLH1 and KNAT3 with AtOFP5 (Pagnussat et al, 2007), and KNAT7 with OFP1 and OFP4 (Li et al, 2011a). The interaction of KNAT7 is mediated by the HD (Li et al, 2011a).…”

“…BLH1, BLH7, and KNAT1 interact with AtOFP1 (Hackbusch et al, 2005), BLH1 and KNAT3 with AtOFP5 (Pagnussat et al, 2007), and KNAT7 with OFP1 and OFP4 (Li et al, 2011a). The interaction of KNAT7 is mediated by the HD (Li et al, 2011a). However, STM shows no interaction with AtOFPs (Hackbusch et al, 2005).…”

The Genetics of Leaf Flecking in Maize and Its Relationship to Plant Defense and Disease Resistance

“…Homologs of OFP4 are transcriptional repressors in the plant-specific ovate family that regulate plant growth and development. The OFP4 transcription factor interacts with KNAT7 to regulate secondary cell wall formation (Li et al, 2011;Wang et al, 2011).…”

Mapping of two suppressors of OVATE (sov) loci in tomato

“…OVATE encodes a member of the OFP family and its members are characterized to function as transcriptional repressors, including the expression of GA20 oxidase 1 (Liu et al, 2002;Hackbusch et al, 2005;Wang et al, 2007Wang et al, , 2011. However, details of the role of OFP members in diverse processes in plant growth and development are unclear as loss of function mutations in the Arabidopsis OFP genes have no or very subtle phenotypes (Wang et al, 2010;Li et al, 2011). By contrast, a loss-of-function mutation in OVATE in tomato is the basis for an elongated fruit shape (Liu et al, 2002).…”