Abstract
We recently identified an Arabidopsis gain-of-function mutant of plastidic invertase (INV-E), sicy-192, as sucrose sensitive mutant. On treatment with sucrose, the expression of photosynthesis- and nitrogen assimilation-related genes was respective lower and higher in the mutants, suggesting that INV-E participates in regulating the carbon/nitrogen (C/N) balance. Expression of photosynthesis-related genes encoded by the nuclear genome is under control of the plastid signaling derived from plastid gene expression (PGE). To clarify the involvement of INV-E in the plastid signaling, we analyzed PGE in sicy-192 mutants on treatment with sucrose.
The transcript levels of plastid genes downstream of plastid-encoded RNA polymerase (PEP), but not of nuclear-encoded plastid RNA polymerase (NEP), were significantly reduced in the sicy-192 mutants on treatment with sucrose. Moreover, the expression of GLK1 and GLK2, components of plastid signaling, was down-regulated in the sicy-192 mutants. Now, we are analyzing the effect of treatment with sucrose on the PGE and nuclear gene expression in the wild-type, sicy-192, and knockout mutants lacking INV-E.
