INVESTIGADORES
PALATNIK Javier Fernando
artículos
Título:
miR396 affects mycorrhization and root meristem activity in the legume Medicago truncatula.
Autor/es:
BAZIN J; KHAN GA; COMBIER JP; BUSTOS-SANMAMED P; DEBERNARDI JM; RODRIGUEZ R; SORIN C; PALATNIK J; HARTMANN C; CRESPI M; LELANDAIS-BRIÈRE C
Revista:
PLANT JOURNAL
Editorial:
WILEY-BLACKWELL PUBLISHING, INC
Referencias:
Año: 2013 p. 920 - 934
ISSN:
0960-7412
Resumen:
The root system is crucial for acquisition of resources from the soil.
In legumes, the efficiency of mineral and water uptake by the roots may
be reinforced due to establishment of symbiotic relationships with
mycorrhizal fungi and interactions with soil rhizobia. Here, we
investigated the role of miR396 in regulating the architecture of the
root system and in symbiotic interactions in the model legume Medicago
truncatula. Analyses with promoter-GUS fusions suggested that the
mtr-miR396a and miR396b genes are highly expressed in root tips,
preferentially in the transition zone, and display distinct expression
profiles during lateral root and nodule development. Transgenic roots of
composite plants that over-express the miR396b precursor showed lower
expression of six growth-regulating factor genes (MtGRF) and two
bHLH79-like target genes, as well as reduced growth and mycorrhizal
associations. miR396 inactivation by mimicry caused contrasting
tendencies, with increased target expression, higher root biomass and
more efficient colonization by arbuscular mycorrhizal fungi. In contrast
to MtbHLH79, repression of three GRF targets by RNA interference
severely impaired root growth. Early activation of mtr-miR396b,
concomitant with post-transcriptional repression of MtGRF5 expression,
was also observed in response to exogenous brassinosteroids. Growth
limitation in miR396 over-expressing roots correlated with a reduction
in cell-cycle gene expression and the number of dividing cells in the
root apical meristem. These results link the miR396 network to the
regulation of root growth and mycorrhizal associations in plants.