Identification, characterization of an AP2/ERF transcription factor that promotes adventitious, lateral root formation in Populus

Abstract

Using activation tagging in Populus, we have identified five mutant lines showing changes in their adventitious rooting. Among the affected lines, three showed increased and two decreased adventitious rooting. We have positioned the tag in the mutant lines via recovering genomic sequences flanking the left-hand border of the activation tagging vector and validated the transcriptional activation of the proximal genes. We further characterized one line in which the cause of the observed rooting phenotype was up-regulation of a gene encoding a transcription factor of the AP2/ERF family of unknown function (PtaERF003). We show, through retransformation, that this gene has a positive effect on both adventitious and lateral root proliferation. Comparative expression analyses show that the phenotype does not result from ectopic expression but rather up-regulation of the native expression pattern of the gene. PtaERF003 function is linked to auxin signal transduction pathway, as suggested by the rapid induction and accentuated phenotypes of the transgenic plants in presence of the hormone. Upregulation of PtaERF003 led to most significant metabolic changes in the shoot suggesting of a broader regulatory role of the gene that is not restricted to root growth and development. Our study shows that dominant tagging approaches in poplar can successfully identify novel molecular factors controlling adventitious and lateral root formation in woody plants. Such discoveries can lead to technologies that can increase root proliferation and, thus, have significant economic and environmental benefits.

The AP2/ERF transcription factor SlERF52 functions in flower pedicel abscission in tomato

“…2A). This group includes: Arabidopsis WAX INDUCER 1 (WIN1)/SHINE1 (SHN1), SHN2, and SHN3, which regulate cutin biosynthesis and abscission of floral organs (Aharoni et al , 2004; Broun et al , 2004; Shi et al , 2011 b ); the tomato homologue of SHN3 (SlSHN3) (Shi et al , 2013); barley ( Hordeum vulgare ) NUDUM (NUD), which regulates lipid biosynthesis for hull-caryopsis adhesion of grain (Taketa et al , 2008); tomato LeERF1, which regulates ethylene signalling (Li et al , 2007); Medicago truncatula ERF REQUIRED FOR NODULE DIFFERENTIATION (EFD) (Vernie et al , 2008); and poplar ( Populus tremula × P. alba ) PtaERF003, which is involved in adventitious and lateral root formation (Trupiano et al , 2013). Group Va ERFs have three conserved domains: the AP2/ERF domain, conserved motif V (CMV)-1, and CMV-2 at the C-terminus (Fig.…”

“…1A), indicating that SlERF52 may mediate the effect of MC , J , and SlMBP21 on these meristem-associated regulators. Two SlERF52 homologues that belong to the incomplete CMV-1 type subgroup regulate plant development through modulation of meristem activity: medicago EFD controls formation of root nodule meristems (Vernie et al , 2008) and poplar PtaERF003 controls formation and growth of adventitious and lateral root meristems (Trupiano et al , 2013). Therefore, the control of meristem-associated regulation may be a conserved biological function for the group Va ERFs with incomplete CMV-1 motifs.…”

Comparative transcriptional analysis provides new insights into the molecular basis of adventitious rooting recalcitrance in Eucalyptus

“…In poplar, a cytokinin type-B response regulator PtRR13was found to be a negative regulator of AR, inhibiting the transcription of two APETALA2/ETHYLENE RESPONSE FACTOR (AP2/ERF) genes [23]. Recently, a member of AP2/ERF family PtERF003was determined as a positive regulator of AR in poplar, being upregulated by auxin [21]. These previous studies support our findings about the expression of the cytokinin type-B response regulator ARR1, which was reduced by auxin treatment in the difficult-to-root species and remained basally expressed in E. grandis.…”

“…Ethylene may act both as positive and negative regulator of AR, depending on the rooting phase and species [6]. The upregulation of PtERF003, a gene encoding a transcription factor of the AP2/ERF family of unknown function in poplar, had a positive effect on both adventitious and lateral root proliferation [21], probably as a result of the auxin-ethylene crosstalk. AINTEGUMENTA LIKE1 (PtAIL1), another AP2 member, controls development of adventitious root primordia [22].…”

Screening of proteins interacting with ERF transcriptional factor from Populus simonii × P.nigra by yeast two-hybrid method

“…Ethylene-responsive factors (ERF) are one of the largest groups of TFs in plants and are closely related to the response of plants to biotic and abiotic stress [2]. ERF genes have been cloned and analyzed in wheat [3], Arabidopsis thaliana [4], grape [5], Jatropha curcas [6], cotton [7], soybean [8], Hevea brasiliensis [9], tobacco [10], potato [11], maize [12] and poplar [13,14]. Fifty-eight transcription factor families have been found in the poplar genome, encoding 4287 different transcription factors containing 209 AP2/ERF transcription factors [15].…”