The MADS transcription factor CmANR1 positively modulates root system development by directly regulating CmPIN2 in chrysanthemum

Abstract

Plant root systems are essential for many physiological processes, including water and nutrient absorption. MADS-box transcription factor (TF) genes have been characterized as the important regulators of root development in plants; however, the underlying mechanism is largely unknown, including chrysanthemum. Here, it was found that the overexpression of CmANR1, a chrysanthemum MADS-box TF gene, promoted both adventitious root (AR) and lateral root (LR) development in chrysanthemum. Whole transcriptome sequencing analysis revealed a series of differentially expressed unigenes (DEGs) in the roots of CmANR1-transgenic chrysanthemum plants compared to wild-type plants. Functional annotation of these DEGs by alignment with Gene Ontology (GO) terms and biochemical pathway Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis indicated that CmANR1 TF exhibited “DNA binding” and “catalytic” activity, as well as participated in “phytohormone signal transduction”. Both chromatin immunoprecipitation–polymerase chain reaction (ChIP-PCR) and gel electrophoresis mobility shift assays (EMSA) indicated the direct binding of CmPIN2 to the recognition site CArG-box motif by CmANR1. Finally, a firefly luciferase imaging assay demonstrated the transcriptional activation of CmPIN2 by CmANR1 in vivo. Overall, our results provide novel insights into the mechanisms of MADS-box TF CmANR1 modulation of both AR and LR development, which occurs by directly regulating auxin transport gene CmPIN2 in chrysanthemum.

MADS‐box genes underground becoming mainstream: plant root developmental mechanisms

“…CmANR1 also regulates PIN transporters expression in Chrysanthemum (Fig. ; Yu LH et al ., ; Sun et al ., ). At the protein level, CmANR1 interacts with itself and with CmAGL21 in a two‐hybrid system, indicating that CmANR1 homodimers and the heterodimers with AGL21 cooperate in LR development (Sun et al ., ).…”

“…The OE of CmANR1 in Arabidopsis also affects free indoleacetic acid levels mainly in the tips of LRs, and it regulates genes that participate in local auxin biosynthesis, auxin polar transport, calcium ion signaling, ethylene biosynthesis and cell‐cycle‐related processes (Fig. ; Sun et al ., , b). The OE of CmANR1 in Chrysanthemum also affects the development of adventitious and LRs (Sun et al ., ).…”

OsSPL3, an SBP-Domain Protein, Regulates Crown Root Development in Rice

“…It is reported in Arabidopsis that the MADS transcription factor XAANTAL2 modulates auxin transport during root development by directly regulating PIN expression (Garay-Arroyo et al, 2013). Recently, the MADS transcription factor chrysanthemum homolog of the Arabidopsis protein AtANR1 was reported to modulates chrysanthemum adventitious root and lateral root development by directly regulating CmPIN2 expression (Sun et al, 2018). These results suggest that the OsSPL3-OsMADS50 module might be directly involved in regulating OsPIN2, OsPIN5a, and OsPIN5c expression to modulate crown root development.…”

“…development in cereals and Arabidopsis (Arora et al, 2007;Yan et al, 2016). MADS-box transcription factors were also found to play important roles in root development (Garay-Arroyo et al, 2013;Yu et al, 2014Yu et al, , 2015Gao et al, 2018;Sun et al, 2018). However, to date, no MADS-box genes has been reported to function in crown root development in cereals.…”

Radial or Bilateral? The Molecular Basis of Floral Symmetry

“…Among them, the MADS-box family is one of the most ancient, present since the evolution of the Chlorophyta [12]. The MADS-box TFs are involved in a wide range of developmental pathways, from spore germination [14], gametophyte and sporophyte generation [14,15], the formation of motile flagella in sperms of non-seed plants [16], to root development [17][18][19], abiotic stress responses [20], tuber dormancy [21], and fruit expansion [22]. In addition, they have been recruited in the pathway that drives the determination of flower organs, as explained by the canonical ABCDE model (mainly in eudicots) and its modifications (e.g., the fading borders in basal angiosperms, magnoliids, and basal eudicots, and the orchid code model in orchids) [23][24][25][26][27][28].…”