MORF9 mediating plastid RNA editing influences Arabidopsis root growth
under sugar starvation
Abstract
RNA editing converts cytidines to uridines in the RNAs transcribed from
the chloroplast and mitochondrial genomes in flowering plants. Multiple
organellar RNA editing factor (MORF) complex is discovered to be highly
associated with C-to-U RNA editing activity of vascular plant editosome.
However, mechanism of MORF9 mediating plastid RNA editing controlling
plant development and in response to environmental cues remains limited.
In this study, we found that loss of MORF9 function impaired PSII
efficiency, NDH activity, and carbohydrate production, rapidly promoted
nuclear gene expression including sucrose transporter and sugar/energy
responsive genes, exhibiting a retard seedling development under sugar
starvation condition. When exogenous application of sugar increased
transcript and protein level of MORF9 and MORF2 in wild-type, and
enhanced the decreasing of matK-706C, accD-794C, ndhD-383C
and ndhF-290C RNA editing efficiency in morf9 mutant, and
partially recovered altered cell division of root meristem zone, and
nuclear gene expression in morf9 mutant. Using gin2, snrk1,
morf9 single and double mutants and overexpressing SnRK1 (KIN10)
or HXK1 in morf9 mutant background genetically addressed
that RNA editing efficiency of ndhD-383C and ndhF-290C
sites was declined in the gin2morf9, that of matK-706C,
accD-794C, ndhD-383C and ndhF-290C sites was significantly declined in
the snrk1morf9, while overexpressing HXK1 or SnRK1
promoted RNA editing rate of matK, accD, ndhD, and
ndhF in leaves of morf9 mutant,indicating that HXK1 might
require for MORF9 mediating ndhD-383C and ndhF-290C
editing, SnRK1 only require for MORF9 mediating ndhF-290C site
editing. It suggests that sugar as an energy/sugar signal impairs MORF9
mediating plastid RNA editing affecting plant root development.