Plants continuously produce new organs throughout their life, and this special feature is due to the existence of stem cell-containing structures named meristems. The shoot apical meristem (SAM), located at the shoot apex, provides all the aerial parts of the plant, such as leaves, stems, or flowers. Thus, the proper function and maintenance of the SAM are crucial for building the plant architecture, and ensuring shoot growth and fruit production, which are fundamental factors to improve crop yield.

In our group, we are interested on understanding how different hormones and genetic networks regulate SAM function and the balance between stem cell proliferation and differentiation. In particular, our main objectives are: (i) to investigate whether less well characterized hormones in the context of SAM homeostasis may also play a role in its regulation, (ii) to extend our knowledge about the gene regulatory networks acting downstream of these hormones, and (iii) to study the potential cross-talk between different hormones in the SAM. To shed light in this regard, we combine meristem morphodynamics and live imaging assays, genetic analyses, hormonal or chemical treatment experiments and gene expression assays.

1. Balanzà V, Merelo P*, Ferrándiz F. 2023. Flowering also has to end: knowns and
unknowns of reproductive arrest in monocarpic plants. J Exp Bot 14: 3951–3960. doi:
https://doi.org/10.1093/jxb/erad213

2. Merelo P*, González-Cuadra I, Ferrándiz C. 2022. A cellular analysis of meristem activity
at the end of flowering points to cytokinin as a major regulator of proliferative arrest in
Arabidopsis. Curr Biol 32: 749-762. doi: https://doi.org/10.1016/j.cub.2021.11.069

3. Tadeo FR, Agustí J, Merelo P, Talón M. 2023. Laser Microdissection: A High-Precision
Approach to Isolate Specific Cell Types from Any Plant Species for Downstream Molecular
Analyses. Methods Mol Biol 2642: 365-373. doi: 10.1007/978-1-0716-3044-0_19

* Co-corresponding author

1. Ramón y Cajal fellowship (RYC2021-034342-IP). PI: Paz Merelo. IBMCP. 2023-2027.
2. Proyecto de Generación de Conocimiento (PID2022-140882OB-I00). Title: Regulation of Shoot Apical Meristem FUNction by hormone crosstalk and nutrient availability (SAMFUN). PI: Paz Merelo. IBMCP. 2023-2025.
3. Proyecto de Grupos de Investigación de Excelencia Prometeo (CIPROM/2022/01). Cristina Ferrándiz (PI), Paz Merelo (Team member, 1/8). IBMCP. 2023.
4. Characterization of the global proliferative arrest and its potential as a breeding target in cereals (Late-GPA-Plants; ComFuturo). PI: Paz Merelo. IBMCP. 2018-2021.

1. Merelo P, Paredes EB, Heisler MG, Wenkel S. 2017. The shady side of leaf development: the role of the REVOLUTA/KANADI1 module in leaf patterning and auxin-mediated growth promotion. Curr Opin Plant Biol 2: 111-116.
2. Merelo P, Agustí J, Arbona V… Talón M, Tadeo FR (CA) (1/12). 2017. Cell wall remodeling in abscission zone cells during ethylene-promoted fruit abscission in Citrus. Front Plant Sci 2: 126.
3. Merelo P, Ram H, Pia Caggiano M… Wenkel S (CA), Heisler MG (CA) (1/11). 2016. Regulation of MIR165/166 by class II and class III homeodomain leucine zipper proteins establishes leaf polarity. PNAS 113: 11973-11978.
4. Merelo P, Xie Y, Brand L, Ott F, Weigel D, Bowman JL, Heisler MG, Wenkel S. 2013. Genome-wide identification of KANADI1 target genes. PLoS One 14: e77341.
5. Kraiselburd I, Daurelio LD, Tondo ML, Merelo P, Cortadi AA, Talón M, Tadeo FR, Orellano EG. 2013. The LOV protein of Xanthomonas citri subsp. citri plays a significant role in the counteraction of plant immune responses during citrus canker. PLoS One 8: e80930.
6. Estornell LH, Agustí J, Merelo P, Talón M, Tadeo FR. 2013. Elucidating mechanisms underlying organ abscission. Plant Sci 199: 48-60.
7. Caruso M, Merelo P, Distefano G, La Malfa S, Lo Piero AR, Tadeo FR, Talon M, Gentile A. 2012. Comparative transcriptome analysis of stylar canal cells identifies novel candidate genes implicated in the self-incompatibility response of Citrus clementina. BMC Plant Biol 14: 20.
8. Agustí J, Merelo P, Cercós M, Tadeo FR, Talón M. 2009. Comparative transcriptional survey between laser-microdissected cells from laminar abscission zone and petiolar cortical tissue during ethylene-promoted abscission in citrus leaves. BMC Plant Biol 23: 127.
9. Agustí J, Merelo P; Cercós M; Tadeo FR; Talón M. 2008. Ethylene-induced differential gene expression during abscission of citrus leaves. J Exp Bot 59: 2717-2733.

Study of hormonal signalling and FRUITFULL mode of action during the proliferative arrest in Arabidopsis thaliana. Student: Irene González Cuadra. Co-directors: Cristina Ferrándiz and Paz Merelo. UPV. 2020-2024.