Biology subjects

Possenti, M.

Publications and source records attributed to Possenti, M..

3 recordsLinked to original sources

bioRxiv2026

Auxin and cytokinin antagonistically regulate Arabidopsis root distal stem cell fate through opposing pairs of HD-Zip II transcription factors

The antagonistic action of auxin (IAA) and cytokinin (CK) regulates several aspects of plant development including stem cell specification and maintenance. In the Arabidopsis thaliana root, the fate of distal stem cells (DSCs) is mainly regulated by IAA, while the function of CK is still ill-defined. Here, by investigating the role of the HD-Zip II transcription factor family in distal tissues, we uncover CK as a proliferative input for DSCs, acting in opposition to IAA. We show that opposing pairs of HD-Zip II proteins regulate DSCs fate by integrating IAA and CK signals. The {delta} module, composed of HAT3 and ATHB4, is activated by CK and promotes DSCs division. Conversely, the {gamma} module, constituted by HAT1 and ATHB2, acts downstream of IAA to repress CK biosynthesis and DSCs division. The mutual inhibition between {delta} and {gamma} modules downstream of opposite hormone inputs sustains the precise regulation of DSCs homeostasis.

plant biology↗

bioRxiv2023

HD-Zip II transcription factors control distal stem cell fate in Arabidopsis roots by linking auxin signaling to the FEZ/SOMBRERO pathway

In multicellular organisms, specialized tissues are generated by specific populations of stem cells through cycles of asymmetric cell divisions, where one daughter undergoes differentiation and the other maintains proliferative properties. In Arabidopsis thaliana roots, the columella - a gravity-sensing tissue which protects and defines the position of the stem cell niche - represents a typical example of a tissue whose organization is exclusively determined by the balance between proliferation and differentiation. The columella derives from a single layer of stem cells through a binary cell fate switch that is precisely controlled by multiple, independent regulatory inputs. Here, we show that the HD-Zip II transcription factors HAT3, ATHB4, and AHTB2, redundantly regulate columella stem cell fate and patterning in the Arabidopsis root. The HD-Zip II transcription factors promote columella stem cell proliferation by acting as effectors of the FEZ/SMB circuit and, at the same time, by interfering with auxin signaling to counteract hormone-induced differentiation. Overall, our work shows that HD-Zip II connect two opposing parallel inputs to fine tune the balance between proliferation and differentiation in columella stem cells. Summary statementHD-Zip II transcription factors redundantly regulate columella stem cells activity by counteracting auxin-mediated differentiation downstream of the FEZ/SMB proliferative input

plant biology↗

bioRxiv2020

DRT111/SFPS splicing factor controls ABA sensitivity in Arabidopsis seed development and germination

RNA splicing is a fundamental mechanism contributing to the definition of the cellular protein population in any given environmental condition. DRT111/SFPS is a splicing factor previously shown to interact with phytochromeB and characterized for its role in splicing of pre-mRNAs involved in photomorphogenesis. Here, we show that DRT111 interacts with Arabidopsis Splicing Factor 1 (SF1), involved in 3 splicing site recognition. Double and triple mutant analysis shows that DRT111 controls splicing of ABI3 and acts upstream of the splicing factor SUPPRESSOR OF ABI3-5 (SUA). DRT111 is highly expressed in seeds and stomata of Arabidopsis and is induced by long-term treatments with polyethylene glycol and ABA. DRT111 knock-out mutants are defective in ABA-induced stomatal closure and are hypersensitive to ABA during seed germination. Conversely, DRT111 over-expressing plants show ABA hyposensitive seed germination. RNAseq experiments show that in dry seeds, DRT111 controls expression and splicing of genes involved in response to osmotic stress and ABA, light signaling and mRNA splicing, including targets of ABSCISIC ACID INSENSITIVE3 (ABI3) and PHYTOCHROME INTERACTING FACTORs (PIFs). Consistently, expression of the germination inhibitor SOMNUS, induced by ABI3 and PIF1 is up-regulated in imbibed seeds of drt111-2 mutants. Altogether, these results indicate that DRT111 controls sensitivity to abscisic acid (ABA) during seed development, germination and stomatal movements and constitutes a point of integration of the ABA- and light-regulated pathways to control seed germination. One Sentence SummaryArabidopsis splicing factor DRT111/SFPS is required for ABA-mediated responses in seeds

plant biology↗