Dr. Amal J. Johnston
Dr. Amal J. Johnston
Im Neuenheimer Feld 230
Fon +49 6221 54-5628
Fax +49 6221 54-5678
ed.grebledieh-inu.soc TEA notsnhoj.lama
Research Group Germline Biology
Figure 1. Ontogeny of female germline (A-D) and ensuing reproductive processes (E-G). Depicted are mRNA signals: prior meiosis (A,B), upon meiosis (C), egg cell (D), zygote (F) and placental endosperm cells (G). Fertilisation of ovaries in a flower (E).
Germlines are organs or cell populations that produce gametes such as the egg and the sperm cell. They contain, and faithfully transmit, the parental genetic information to the offspring upon sexual reproduction. Whereas in animals germ cells represent stem cell populations that are set aside early in development during embryogenesis, plant germlines, otherwise known as gametophytes, differentiate late in development. Genetic and/or epigenetic modifications in female germline development may lead to clonal offspring production in case of asexual organisms via a natural cloning process known as apomixis. The protein Retinoblastoma (pRb) and its homologues are evolutionarily ancient transcription factors and repressors of the cell cycle throughout most, if not all eukaryotic systems. While complete depletion of pRb leads to cancer and lethality in most of the animal systems, we exploit plant model systems that efficiently tolerate mutation load, in order to dissect how the pRb and its regulatory network regulate cell fate determination and differentiation during germline development and ensuing reproductive processes such as genomic imprinting. Of focus are evo-devo investigations on adaptive evolution of sex-specific genetic and epigenetic mechanisms operating during sexual and asexual germline development. In addition to deciphering the basic molecular genetics of the pRb-associated carcinogenic pathways relevant to plant and animal systems, our applied goal is to deliver biotechnological know-hows of sexual and apomictic reproduction, and stress tolerance.
Female gametophytic cell specification and seed development require the function of the putative Arabidopsis INCENP ortholog WYRD (2011) Kirioukhova O., Johnston A.J., et al. Development 138:3409-20.
Members of the RKD transcription factor family induce an egg cell-like gene expression program (2011) Koszegi, D., Johnston, A.J., et al. Plant J. 67:280-91
Dosage-sensitive function of RETINOBLASTOMA RELATED and convergent epigenetic control are required during the Arabidopsis life cycle (2010) Johnston, A.J., Kirioukhova, O., et al. PLoS Genet. 6, e1000988
Identification and genetic analysis of the APOSPORY locus in Hypericum perforatum (2010) Schallau, A., Arzenton, F., Johnston, A.J., et al. Plant J. 62, 773-784.
TRAUCO, a trithorax group protein homologue, is essential for early embryogenesis in Arabidopsis thaliana (2010) Aquea, F., Johnston, A.J., et al. J Exp Bot. 61, 1215-1224.
Gametic differentiation and imprinting control in plants: A crosstalk between RBR and chromatin (2009) Johnston, A.J., and Gruissem, W. Commun. Integr. Biol. 2, 144-146.
A dynamic reciprocal RBR-PRC2 regulatory circuit controls Arabidopsis gametophyte development (2008) Johnston, A.J., Matveeva, L., Kirioukhova, O., et al. Curr. Biol. 18, 1680-1686.
Genetic subtraction profiling identifies genes essential for Arabidopsis reproduction and reveals interaction between the female gametophyte and the maternal sporophyte (2007) Johnston, A.J., Meier, P., et al. Genome Biol. 8, R204