@article{manrique_cavalleri_guazzotti_villarino_simonini_bombarely_higashiyama_grossniklaus_mizzotti_pereira_et al._2023, title={HISTONE DEACETYLASE19 Controls Ovule Number Determination and Transmitting Tract Differentiation}, volume={12}, ISSN={["1532-2548"]}, DOI={10.1093/plphys/kiad629}, abstractNote={Abstract The gynoecium is critical for the reproduction of flowering plants as it contains the ovules and the tissues that foster pollen germination, growth, and guidance. These tissues, known as the reproductive tract (ReT), comprise the stigma, style, and transmitting tract (TT). The ReT and ovules originate from the carpel margin meristem (CMM) within the pistil. SHOOT MERISTEMLESS (STM) is a key transcription factor for meristem formation and maintenance. In all above-ground meristems, including the CMM, local STM downregulation is required for organ formation. However, how this downregulation is achieved in the CMM is unknown. Here, we have studied the role of HISTONE DEACETYLASE 19 (HDA19) in Arabidopsis (Arabidopsis thaliana) during ovule and ReT differentiation based on the observation that the hda19-3 mutant displays a reduced ovule number and fails to differentiate the TT properly. Fluorescence-activated cell sorting coupled with RNA-sequencing revealed that in the CMM of hda19-3 mutants, genes promoting organ development are downregulated while meristematic markers, including STM, are upregulated. HDA19 was essential to downregulate STM in the CMM, thereby allowing ovule formation and TT differentiation. STM is ectopically expressed in hda19-3 at intermediate stages of pistil development, and its downregulation by RNA interference alleviated the hda19-3 phenotype. Chromatin immunoprecipitation assays indicated that STM is a direct target of HDA19 during pistil development and that the transcription factor SEEDSTICK is also required to regulate STM via histone acetylation. Thus, we identified factors required for the downregulation of STM in the CMM, which is necessary for organogenesis and tissue differentiation.}, journal={PLANT PHYSIOLOGY}, author={Manrique, Silvia and Cavalleri, Alex and Guazzotti, Andrea and Villarino, Gonzalo H. and Simonini, Sara and Bombarely, Aureliano and Higashiyama, Tetsuya and Grossniklaus, Ueli and Mizzotti, Chiara and Pereira, Ana Marta and et al.}, year={2023}, month={Dec} }
 @article{zheng_nagpal_villarino_trinidad_bird_huang_reed_2019, title={miR167 limits anther growth to potentiate anther dehiscence}, volume={146}, ISSN={["1477-9129"]}, DOI={10.1242/dev.174375}, abstractNote={ABSTRACT In flowering plants, anther dehiscence and pollen release are essential for sexual reproduction. Anthers dehisce after cell wall degradation weakens stomium cell junctions in each anther locule, and desiccation creates mechanical forces that open the locules. Either effect or both together may break stomium cell junctions. The microRNA miR167 negatively regulates ARF6 and ARF8, which encode auxin response transcription factors. Arabidopsis mARF6 or mARF8 plants with mutated miR167 target sites have defective anther dehiscence and ovule development. Null mir167a mutations recapitulated mARF6 and mARF8 anther and ovule phenotypes, indicating that MIR167a is the main miR167 precursor gene that delimits ARF6 and ARF8 expression in these organs. Anthers of mir167a or mARF6/8 plants overexpressed genes encoding cell wall loosening functions associated with cell expansion, and grew larger than wild-type anthers did starting at flower stage 11. Experimental desiccation enabled dehiscence of miR167-deficient anthers, indicating competence to dehisce. Conversely, high humidity conditions delayed anther dehiscence in wild-type flowers. These results support a model in which miR167-mediated anther growth arrest permits anther dehiscence. Without miR167 regulation, excess anther growth delays dehiscence by prolonging desiccation. Summary: The microRNA mir167 limits Arabidopsis anther expansion growth shortly before flowers open. Without this regulation, enlarged anthers do not desiccate enough to dehisce and release pollen.}, number={14}, journal={DEVELOPMENT}, author={Zheng, Lanjie and Nagpal, Punita and Villarino, Gonzalo and Trinidad, Brendan and Bird, Laurina and Huang, Yubi and Reed, Jason W.}, year={2019}, month={Jul} }
 @article{villarino_hu_manrique_flores-vergara_sehra_robles_brumos_stepanova_colombo_sundberg_et al._2016, title={Transcriptomic Signature of the SHATTERPROOF2 Expression Domain Reveals the Meristematic Nature of Arabidopsis Gynoecial Medial Domain}, volume={171}, ISSN={["1532-2548"]}, url={http://europepmc.org/abstract/med/26983993}, DOI={10.1104/pp.15.01845}, abstractNote={Transcriptional profiles of spatially and temporally restricted cell populations from the Arabidopsis gynoecium reveals the meristematic nature of the gynoecial medial domain. Plant meristems, like animal stem cell niches, maintain a pool of multipotent, undifferentiated cells that divide and differentiate to give rise to organs. In Arabidopsis (Arabidopsis thaliana), the carpel margin meristem is a vital meristematic structure that generates ovules from the medial domain of the gynoecium, the female floral reproductive structure. The molecular mechanisms that specify this meristematic region and regulate its organogenic potential are poorly understood. Here, we present a novel approach to analyze the transcriptional signature of the medial domain of the Arabidopsis gynoecium, highlighting the developmental stages that immediately proceed ovule initiation, the earliest stages of seed development. Using a floral synchronization system and a SHATTERPROOF2 (SHP2) domain-specific reporter, paired with FACS and RNA sequencing, we assayed the transcriptome of the gynoecial medial domain with temporal and spatial precision. This analysis reveals a set of genes that are differentially expressed within the SHP2 expression domain, including genes that have been shown previously to function during the development of medial domain-derived structures, including the ovules, thus validating our approach. Global analyses of the transcriptomic data set indicate a similarity of the pSHP2-expressing cell population to previously characterized meristematic domains, further supporting the meristematic nature of this gynoecial tissue. Our method identifies additional genes including novel isoforms, cis-natural antisense transcripts, and a previously unrecognized member of the REPRODUCTIVE MERISTEM family of transcriptional regulators that are potential novel regulators of medial domain development. This data set provides genome-wide transcriptional insight into the development of the carpel margin meristem in Arabidopsis.}, number={1}, journal={PLANT PHYSIOLOGY}, author={Villarino, Gonzalo H. and Hu, Qiwen and Manrique, Silvia and Flores-Vergara, Miguel and Sehra, Bhupinder and Robles, Linda and Brumos, Javier and Stepanova, Anna N. and Colombo, Lucia and Sundberg, Eva and et al.}, year={2016}, month={May}, pages={42–61} }