Auxin‐mediated Aux/IAA‐ARF‐HB signaling cascade regulates secondary xylem development in Populus

Abstract

Summary Wood development is strictly regulated by various phytohormones and auxin plays a central regulatory role in this process. However, how the auxin signaling is transducted in developing secondary xylem during wood formation in tree species remains unclear. Here, we identified an Aux/INDOLE‐3‐ACETIC ACID 9 (IAA9)‐AUXIN RESPONSE FACTOR 5 (ARF5) module in Populus tomentosa as a key mediator of auxin signaling to control early developing xylem development. PtoIAA9, a canonical Aux/IAA gene, is predominantly expressed in vascular cambium and developing secondary xylem and induced by exogenous auxin. Overexpression of PtoIAA9m encoding a stabilized IAA9 protein significantly represses secondary xylem development in transgenic poplar. We further showed that PtoIAA9 interacts with PtoARF5 homologs via the C‐terminal III/IV domains. The truncated PtoARF5.1 protein without the III/IV domains rescued defective phenotypes caused by PtoIAA9m. Expression analysis showed that the PtoIAA9‐PtoARF5 module regulated the expression of genes associated with secondary vascular development in PtoIAA9m‐ and PtoARF5.1‐overexpressing plants. Furthermore, PtoARF5.1 could bind to the promoters of two Class III homeodomain‐leucine zipper (HD‐ZIP III) genes, PtoHB7 and PtoHB8, to modulate secondary xylem formation. Taken together, our results suggest that the Aux/IAA9‐ARF5 module is required for auxin signaling to regulate wood formation via orchestrating the expression of HD‐ZIP III transcription factors in poplar.

Expression Profile of Laccase Gene Family in White-Rot Basidiomycete Lentinula edodes under Different Environmental Stresses

“…In this study, the expression profiles of Lelccs (Lelcc13, Lelcc14) were extremely similar to those of LephrA and LephrB. Two genes with similar expression profiles were reported to be regulated by the same transcription factor in Populus [50]. This result indicated that Lelcc13, Lelcc14, and blue-light photoreceptors were regulated by the same transcription factor or had similar functions.…”

Genome-wide Identification of Long Non-coding RNAs and Their Potential Functions in Poplar Growth and Phenylalanine Biosynthesis

“…The insertion of ve cisgenes encoding gibberellin metabolism or signal proteins affects plant growth [31]. The auxin-mediated Aux/IAA-ARF-HB signal cascade regulates the development of the secondary xylem of poplar [26]. And it was found that a large number of auxin and gibberellin related lncRNA-mRNA coexpression networks were identi ed (Fig.…”

“…Hormones, such as auxin, cytokinin, and gibberellin, play an important role in primay and secondary growth [26,27]. In order to further analyze the relationship between lncRNA and plant hormones, we constructed a co-expression network including auxin, cytokinin, and gibberellin related PCgenes and their regulatory lncRNAs (Fig.…”

Brassinosteroid Signaling Converges With Auxin-Mediated C3H17 to Regulate Xylem Formation in Populus

“…Stem section (8 µm) was cut on a rotary Leica RM 6025 microtome (Leica), mounted onto Superfrost glass slides (Thermo Fisher), and hybridized with the antisense or sense RNA probes. Hybridization and immunological detection were carried out according to the previous description (Xu C. et al, 2019).…”