Biology subjects

Thelander, M.

Publications and source records attributed to Thelander, M..

3 recordsLinked to original sources

bioRxiv2022

MS1/MMD1 homologs in the moss P. patens are required for male and female gametogenesis and likely for sporogenesis

O_LIThe Arabidopsis Plant HomeoDomain (PHD) proteins AtMS1 and AtMMD1 provide chromatin-mediated transcriptional regulation essential for tapetum-dependent pollen formation. Such pollen-based male gametogenesis is a derived trait of seed plants. Male gametogenesis in the common ancestors of land plants is instead likely to have been reminiscent of that in extant bryophytes where flagellated sperms are produced by an elaborate gametophyte generation. Still, also bryophytes possess MS1/MMD1-related PHD proteins. C_LIO_LIWe addressed the function of two MS1/MMD1-homologs in the bryophyte model moss Physcomitrium patens by the generation and analysis of reporter and loss-of-function lines. C_LIO_LIThe two genes are together essential for both male and female fertility by providing cell autonomous functions in the gamete-producing inner cells of antheridia and archegonia. They are furthermore expressed in the diploid sporophyte generation suggesting a function during sporogenesis, a process proposed related by descent to pollen formation in angiosperms. C_LIO_LIWe propose that the moss MS1/MMD1-related regulatory network required for completion of male and female gametogenesis and possibly for sporogenesis, represent a heritage from ancestral land plants. C_LI

plant biology↗

bioRxiv2022

Apical and basal auxin sources pattern shoot branching in a moss

Shoot branching mechanisms where branches arise in association with leaves - referred to as lateral or axillary branching - evolved by convergence in the sporophyte of vascular plants and the gametophyte of bryophytes, and accompanied independent events of plant architectural diversification1. Previously, we showed that three hormonal cues, including auxin, have been recruited independently to co-ordinate branch patterning in flowering plant leafy shoots and moss gametophores (Coudert, Palubicki et al., 2015)2-4. Moreover, auxin-mediated apical dominance, which relies on local auxin production, has been proposed as a unifying molecular regulatory mechanism of branch development across land plants5. Whilst our previous work in the moss Physcomitrium patens has gathered indirect evidence supporting the notion that auxin synthesized in gametophore apices regulates branch formation at a distance2, direct genetic evidence for a role of auxin biosynthesis in gametophore branching control is still lacking. Here, we show that gametophore apex decapitation promotes branch emergence through massive and rapid transcriptional reprogramming of auxin-responsive genes and altering auxin biosynthesis gene activity. Specifically, we identify a subset of P. patens TRYPTOPHAN AMINO-TRANSFERASE (TAR) and YUCCA FLAVIN MONOOXYGENASE-LIKE (YUC) auxin biosynthesis genes expressed in apical and basal regions of the gametophore, and show that they are essential for branch initiation and outgrowth control. Our results demonstrate that local auxin biosynthesis coordinates branch patterning in moss and thus constitutes a shared and ancient feature of shoot architecture control in land plants.

plant biology↗

bioRxiv2018

Selective auxin agonists induce specific AUX/IAA protein degradation to modulate plant development

Auxin phytohormones control most aspects of plant development through a complex and interconnected signaling network. In the presence of auxin, AUXIN/INDOLE-3-ACETIC ACID (AUX/IAA) transcriptional repressors are targeted for degradation by the SKP1-CULLIN1-F-BOX (SCF) ubiquitin-protein ligases containing TRANSPORT INHIBITOR RESISTANT 1/AUXIN SIGNALING F-BOX (TIR1/AFB). CULLIN1-neddylation is required for SCFTIR1/AFB functionality as exemplified by mutants deficient in the NEDD8-activating enzyme subunit AUXIN-RESISTANT 1 (AXR1). Here, we report a chemical biology screen that identifies small molecules requiring AXR1 to modulate plant development. We selected four molecules of interest, RubNeddin1 to 4 (RN1 to 4), among which RN3 and RN4 trigger selective auxin responses at transcriptional, biochemical and morphological levels. This selective activity is explained by their ability to promote the interaction between TIR1 and a specific subset of AUX/IAA proteins, stimulating the degradation of particular AUX/IAA combinations. Finally, via a genetic screen using RN4, we revealed that the chromatin remodeling ATPase BRAHMA is implicated in auxin-mediated apical hook development. These results demonstrate the power of selective auxin agonists to dissect auxin perception for plant developmental functions.

plant biology↗