Repression of growth regulating factors by the microRNA396 inhibits cell proliferation by UV-B radiation in Arabidopsis leaves.
Because of their sessile lifestyle, plants are continuously exposed to solar UV-B radiation. Inhibition of leaf growth is one of the most consistent responses of plants upon exposure to UV-B radiation. In this work, we investigated the role of Growth-Regulating Factors (GRFs) and of microRNA miR396 in UV-B-mediated inhibition of leaf growth in Arabidopsis thaliana plants. We demonstrate that miRNA396 is upregulated by UV-B radiation in proliferating tissues and that this induction is correlated with a decrease in GRF1, GRF2, and GRF3 transcripts. Induction of miR396 results in inhibition of cell proliferation, and this outcome is independent of the UV-B photoreceptor UV resistance locus 8, as well as ATM AND RAD3-related and the mitogen-activated protein kinase MPK6, but is dependent on MPK3. Transgenic plants expressing an artificial target mimic directed against miR396 (MIM396) with a decrease in the endogenous microRNA activity or plants expressing miR396-resistant copies of several GRFs are less sensitive to this inhibition. Consequently, at intensities that can induce DNA damage in Arabidopsis plants, UV-B radiation limits leaf growth by inhibiting cell division in proliferating tissues, a process mediated by miR396 and GRFs.
Centro de Estudios Fotosintéticos y Bioquímicos, Universidad Nacional de Rosario, 2000 Rosario, Argentina.
Romina
R
Casadevall
Ramiro E
RE
Rodriguez
Juan M
JM
Debernardi
Javier F
JF
Palatnik
Paula
P
Casati
D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000502:physiology / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism; D002455:Cell Division / Q000528:radiation effects; D049109:Cell Proliferation / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D008954:Models, Biological; D055519:Photoreceptors, Plant / Q000235:genetics / Q000378:metabolism; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000502:physiology / Q000528:radiation effects; D030821:Plants, Genetically Modified; D014466:Ultraviolet Rays
D029681:Arabidopsis Proteins; D002135:Calcium-Binding Proteins; C087620:GF14 protein, Arabidopsis; C572930:MIRN396 microRNA, Arabidopsis; D035683:MicroRNAs; D055519:Photoreceptors, Plant