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A role for the miR396/ GRF network in specification of organ type during flower development, as supported by ectopic expression of P opulus trichocarpa miR396c in transgenic tobacco
Author(s) -
Baucher M.,
Moussawi J.,
Vandeputte O. M.,
Monteyne D.,
Mol A.,
PérezMorga D.,
El Jaziri M.
Publication year - 2013
Publication title -
plant biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 1435-8603
DOI - 10.1111/j.1438-8677.2012.00696.x
Subject(s) - biology , ectopic expression , populus trichocarpa , meristem , gene , transgene , genetics , mutant , microbiology and biotechnology , arabidopsis , fusion protein , genome , recombinant dna
The MIR 396 family, composed of ath‐miR396a and ath‐miR396b in A rabidopsis , is conserved among plant species and is known to target the Growth‐Regulating Factor ( GRF ) gene family. ath‐miR396 overexpressors or grf mutants are characterised by small and narrow leaves and show embryogenic defects such as cotyledon fusion. Heterologous expression of ath‐miR396a has been reported in tobacco and resulted in reduction of the expression of three N t GRF genes. In this study, the precursor of the P opulus trichocarpa ptc‐miR396c , with a mature sequence identical to ath‐miR396b , was expressed under control of the C a MV 35S promoter in tobacco. Typical phenotypes of GRF down‐regulation were observed, including cotyledon fusion and lack of shoot apical meristem ( SAM ). At later stage of growth, transgenic plants had delayed development and altered specification of organ type during flower development. The third and fourth whorls of floral organs were modified into stigmatoid anthers and fasciated carpels, respectively. Several N t GRF genes containing a miR396 binding site were found to be down‐regulated, and the cleavage of their corresponding m RNA at the miR396 binding site was confirmed for two of them using RACE ‐ PCR analysis. The data obtained agree with the functional conservation of the miR396 family in plants and suggest a role for the miR396/ GRF network in determination of floral organ specification.