Monica Pradillo, PI
Juan Luis Santos, PI
Tomás Naranjo Pompa
Nieves Cuñado Rodríguez
Pablo Parra Núñez
Nadia Fernández Jiménez
José Carlos Limón de las Morenas
Bianca Martín Ayuso
Miguel Pachón Peñalba
Patricia González Cediel
María Granell Ruiz
Track record of the group
Studies in plant meiosis have made and continue to make an important contribution to fundamental research aimed at the understanding of this complex division. Indeed plants appear to have relaxed meiotic checkpoints in comparison with other species. This makes plants powerful tools to analyze meiotic progression and allows plant breeding for the generation of new traits of agronomic, environmental and economic importance. Recent studies in the model species Arabidopsis thaliana have substantially improved our understanding of how meiotic recombination is controlled in plants. It allows molecular approaches to be combined with new developments in cytological methods. Nevertheless, in Arabidopsis thaliana, as in other model organisms, there are conspicuous gaps in the understanding of the mechanisms underlying in the first meiotic prophase: pairing, synapsis and recombination and the relationships between them. Our research in the last years has been focused to contribute in some way to fill some of these gaps, especially those related to meiotic recombination.
The factors that control meiotic recombination have the potential to provide the breeder with the means to make fuller use of the genetic variability that is available in crop species. For example, in cereal crops the distribution of reciprocal genetic exchanges (crossovers, COs) is predisposed to the ends of the chromosomes, such that ~30-50% of the genes rarely recombine. Thus, the frequency and distribution of meiotic COs is a major constraint to future crop improvement.
In order to improve our knowledge on the effects of genes involved in the recombination process of Angiosperms we use the plant model species Arabidopsis thaliana, but also crop species such as tetraploid and hexaploid wheat. For this purpose, we have focused our research in the study of some of the cis and trans factors that affect homologous recombination (HR). The cis factors are related to the DNA itself or to the chromatin and the trans factors correspond to the machinery that regulates or catalyzes the HR reaction. Among the former ones, we have studied the effects of the protein complex CAF-1, which is involved in chromatin organization during DNA replication and DNA repair. We have also determined the role of inner nuclear envelope proteins (e.g. SUN proteins) that are part of complexes linking cytoskeletal elements with the nucleoskeleton, connecting telomeres to the force-generating mechanism in the cytoplasm. Among the trans factors, we have analyzed the role of the recombinase RAD51, one of the most important proteins in the HR process. Currently, we are also involved in a project on the role of meiotic recombination in auto- (Arabidopsis) and allopolypoid (wheat, Triticum turgidum) landscapes.
We combine approaches in molecular and new high-resolution cytogenetic techniques to obtain a detailed understanding of the factors that control recombination, providing a basis for the development of strategies to modify recombination in a variety of crop species. Additionally, our participation in different European projects (Marie Curie Initial Training Networks ITN and COST Actions) allows us to maintain synergistic interactions through collaborative research and training networks.
We believe that our research in the identification and characterization of genes that regulate meiotic recombination will contribute to gain control over this process, in terms of modifying frequency and distribution of CO events along plant chromosomes. This knowledge will be essential for plant breeders to effectively engineer the allelic composition of chromosomes.
Most relevant publications
On the role of AtDMC1, AtRAD51 and its paralogs during Arabidopsis meiosis. Pradillo M, Varas J, Oliver C, Santos JL. Front Plant Sci. 2014 Feb 17;5:23. doi: 10.3389/fpls.2014.00023.
On the role of some ARGONAUTE proteins in meiosis and DNA repair in Arabidopsis thaliana. Oliver C, Santos JL, Pradillo M. Front Plant Sci. 2014 May 20;5:177. doi: 10.3389/fpls.2014.00177.
Absence of SUN1 and SUN2 proteins in Arabidopsis thaliana leads to a delay in meiotic progression and defects in synapsis and recombination. Varas J, Graumann K, Osman K, Pradillo M, Evans DE, Santos JL, Armstrong SJ. Plant J. 2015 Jan;81(2):329-46. doi: 10.1111/tpj.12730.
Analysis of the Relationships between DNA Double-Strand Breaks, Synaptonemal Complex and Crossovers Using the Atfas1-4 Mutant. Varas J, Sánchez-Morán E, Copenhaver GP, Santos JL, Pradillo M. PLoS Genet. 2015 Jul 6;11(7):e1005301. doi: 10.1371/journal.pgen.1005301.
Involvement of the Cohesin Cofactor PDS5 (SPO76) During Meiosis and DNA Repair in Arabidopsis thaliana. Pradillo M, Knoll A, Oliver C, Varas J, Corredor E, Puchta H, Santos JL. Front Plant Sci. 2015 Dec 1;6:1034. doi: 10.3389/fpls.2015.01034.
Accurate Chromosome Segregation at First Meiotic Division Requires AGO4, a Protein Involved in RNA-Dependent DNA Methylation in Arabidopsis thaliana. Oliver C, Santos JL, Pradillo M. Genetics. 2016 Oct;204(2):543-553.
The Absence of the Arabidopsis Chaperone Complex CAF-1 Produces Mitotic Chromosome Abnormalities and Changes in the Expression Profiles of Genes Involved in DNA Repair. Varas J, Santos JL, Pradillo M. Front Plant Sci. 2017 Apr 11;8:525. doi: 10.3389/fpls.2017.00525.
Loss of function of Arabidopsis microRNA-machinery genes impairs fertility, and has effects on homologous recombination and meiotic chromatin dynamics. Oliver C, Pradillo M, Jover-Gil S, Cuñado N, Ponce MR, Santos JL. Sci Rep. 2017 Aug 24;7(1):9280. doi: 10.1038/s41598-017-07702-x.
Aim of the research work
Our research aims to unravel the interplay and coordination between the homologous recombination proteins, the chromatin dynamics during meiotic progression and the nuclear envelope. We are also interested in analyzing changes in meiotic chromosome behavior that occur following genome duplication (polyploidy). We mainly use the plant model organism Arabidopsis thaliana. According to H2020 Societal Challenges, our research falls within the remit of ‘Societal Challenge 2: Food security, sustainable agriculture and forestry, marine and maritime and inland water research and the bioeconomy’ and specifically addresses topic SFS-05-2015: Strategies for crop productivity, stability and quality. Our research objectives can be summarized as follows:
- To gain a clearer understanding about the factors and networks that control the formation of meiotic COs.
- To determine the influence that the nuclear envelope has on chromosome dynamics during meiosis.
- To understand how chromosomes solve the meiotic problems that arise after genome duplication.
Finally, we wish to provide a basis for the translation of this fundamental knowledge from Arabidopsis thaliana to crop species.
Research identification web links
https://www.ucm.es/genetica1/juan-luis-santos (personal web)