Auxin Response GeneSlARF3Plays Multiple Roles in Tomato Development and is Involved in the Formation of Epidermal Cells and Trichomes

Abstract

The auxin response factor (ARF) genes encode a large family of proteins involved in auxin signaling transduction. SlARF3, a member of the ARF gene family, encodes a protein containing two conserved domains, B3 and ARF, and lacking an Aux/IAA domain. Expression analysis showed that SlARF3 has a particularly high expression level in trichomes. In situ hybridization also detected the SlARF3 transcripts in epidermal pavement cells of leaves. The physiological function of SlARF3 was studied by using the RNA interference (RNAi) strategy. SlARF3-down-regulated plants exhibited decreased density of epidermal pavement cells and obviously reduced density of type I, V and VI trichomes of leaves, which indicates the important role of SlARF3 in the formation of trichomes and epidermal cells in tomato. The number of shoot xylem cells was also decreased in SlARF3-down-regulated lines. Furthermore, RNA-sequencing (RNA-Seq) analysis identified 51 differentially expressed genes (DEGs) belonging to 14 transcription factor (TF) families, such as MYB, bHLH, WD40 and C2H2 zinc finger. Twenty-seven DEGs were involved in the metabolism and signaling transduction of phytohormones, such as auxin, ethylene and gibberellin. These results indicated the important roles of the TFs and hormones in auxin-dependent transcriptional regulation of trichome formation in tomato. Taken together, our results demonstrate that SlARF3 plays an important role in the formation of epidermal cells and trichomes and reveal novel and specific functions for ARFs in tomato developmental processes.

GhWIP2, a WIP zinc finger protein, suppresses cell expansion in Gerbera hybrida by mediating crosstalk between gibberellin, abscisic acid, and auxin

“…Plant morphogenesis is regulated by coordinated activation of cell differentiation, cell division, and cell expansion; obviously, organ growth is one of best reflections of these processes (Mizukami, ). At the cellular level, organ growth occurs by initial cell proliferation in which cell number increase, followed by cell expansion, which is critically important for the final shape and size of all plant organs (Li et al ., ; Xu et al ., ; Zhang et al ., ; Velasquez et al ., ). Molecular mechanisms that control the cell expansion are not well understood.…”

Down Regulation and Loss of Auxin Response Factor 4 Function Using CRISPR/Cas9 Alters Plant Growth, Stomatal Function and Improves Tomato Tolerance to Salinity and Osmotic Stress

“…In tomato, the ARF gene family is also involved in the control of many physiological processes [5]. Downregulation of ARF3 decreased the density of epidermal cells and trichomes in tomato [11]. The Slarf2A/B mutation leads to a severe fruit ripening inhibition with dramatically reduced ethylene production, while the over-expression of ARF2A resulted in a blotchy ripening pattern in fruit as a result of a significant accumulation of ripening-related genes and metabolites [12].…”

SlARF10, an auxin response factor, is required for chlorophyll and sugar accumulation during tomato fruit development

“…Most ARF proteins contain an N-terminal DNA-binding domain (B3) involved in transcription of auxin response genes, a middle region acting as an activation domain (AD) or repression domain (RD), and a C-terminal dimerization domain (Aux/IAA) requiring the formation of heterodimers or homodimers (Zouine et al ., 2014). An increasing number of studies demonstrate that ARFs play important roles in many developmental processes of tomato (Krogan et al ., 2011; Wang et al ., 2012; Guan et al ., 2013; Ckurshumov et al ., 2014; Liu et al ., 2014; Zhang et al ., 2015). SlARF7 acts as a negative regulator of fruit set and development in tomato (De Jong et al ., 2009).…”

“…SlARF9 is required for regulation of cell division during early tomato fruit development (De Jong et al ., 2015). SlARF3 is involved in the formation of epidermal cells and trichomes (Zhang et al ., 2015). ARF4 was reported to control the accumulation of chlorophyll and starch in the tomato fruit (Jones et al ., 2002; Sagar et al ., 2013).…”