MADS-box genes underground becoming mainstream: plant root developmental mechanisms.

Abstract

Contents Summary I. Introduction II. MADS-box genes in Arabidopsis primary root development III. MADS-box genes function in root development of other plant species IV. MADS-box genes in lateral root development V. Epigenetic regulation of root MADS-box genes VI. MADS-box genes are regulators of root developmental plasticity VII. Unraveling the role of MADS-box genes in angiosperms with contrasting root morphogenetic patterns: a challenge still ahead VIII. Expression patterns and potential functional conservation between different MADS-box genes in roots from different angiosperms IX. Conclusions Acknowledgements References SUMMARY: Plant growth is largely post-embryonic and depends on meristems that are active throughout the lifespan of an individual. Developmental patterns rely on the coordinated spatio-temporal expression of different genes, and the activity of transcription factors is particularly important during most morphogenetic processes. MADS-box genes constitute a transcription factor family in eukaryotes. In Arabidopsis, their proteins participate in all major aspects of shoot development, but their role in root development is still not well characterized. In this review we synthetize current knowledge pertaining to the function of MADS-box genes highly expressed in roots: XAL1, XAL2, ANR1 and AGL21, as well as available data for other MADS-box genes expressed in this organ. The role of Trithorax group and Polycomb group complexes on MADS-box genes epigenetic regulation is also discussed. We argue that understanding the role of MADS-box genes in root development of species with contrasting architectures is still a challenge. Finally, we propose that MADS-box genes are key components of the gene regulatory networks that underlie various gene expression patterns, each one associated with the distinct developmental fates observed in the root. In the case of XAL1 and XAL2, their role within these networks could be mediated by regulatory feedbacks with auxin.