MIR396 AND GROWTH REGULATING FACTORS TRANSCRIPTION FACTORS IN ARABIDOPSIS ROOT DEVELOPMENT

ERCOLI, MA FLORENCIA; MECCHIA, MARTIN; DEBERNARDI, JUAN MANUEL; PALATNIK, JAVIER F; RODRIGUEZ, RAMIRO ESTEBAN

Pto Madryn

Congreso; XLVI Reunión Anual de la Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular; 2010

The indeterminate growth of plants is sustained by the activity of two apical meristems: the root apical meristem (RAM) and the shoot apical meristem (SAM). Leaf primordia are initiated by recruiting cells from the peripheral zone of the SAM and extensive cell proliferation occurs even days after primordia initiation. We have previously shown that miR396 limits the expression of the transcription factors GROWTH REGULATING FACTORS (GRF) to proliferating regions in developing leaves. Besides, high levels of miR396 repress the expression of target GRFs and reduce the proliferative phase during leaf development, leading to smaller leaves with fewer cells. In roots, cell proliferation is confined to a meristematic zone (MZ) at the first 200 micrometers of the organ. Above the MZ, zones of elongation and maturation produce the final mature organ. Here, we describe the role of miR396 and GRFs in Arabidopsis root development. Root growth rate was affected in plants with altered levels of miR396 or GRFs. The cellular basis of this defects was analyzed using laser scanning confocal microscopy on propidium iodide counterstained roots of plants expressing a mitotic reporter gene. Besides, GFP reporters were used to analyze GRF2 and miR396 expression and activity pattern. Finally, microarray expression profiles of the meristematic zone from miR396 overexpressing plants will be presented.