That whatever it was was always at night and though morning would reliably come and snap night off like a light or a finger extended night would always grow back.
In our eyes, this confirms that both SnRK1 kinases phosphorylate bZIP63 under extended night conditions.
In response to starvation (6 hrs extended night EN), band 7 appears as higher phosphorylated form.
Under extended night conditions, an additional band appeared (labelled as band 8), indicating increased phosphorylation of bZIP63.
Proteins were extracted from seedling cultures after 6 hr extended night in the presence or absence of 1% sucrose.
For light/extended night comparison, rosettes of 5 week old plants were collected after 6 hr of light or extended night.
L, light; EN, extended night; D, dark; suc, sucrose; T, trypsin; C, chymotrypsin; L, LysC; S, subtilisin; NLS, nuclear localization signal.
Remarkably, the phosphorylation patterns of different bZIP63 mutants on Phos-tag gels pointed towards S29 as the main target site for AKIN10 under extended night conditions.
Comparison of protein extracts from seedling cultures after 6 hr extended night in the presence or absence of sucrose or leaves harvested after 6 hr of light or extended night revealed strong differences in the phosphorylation patterns of bZIP63.
While exogenous sucrose decreased the global phosphorylation level of bZIP63, extended night treatment further increased its phosphorylation, thus supporting the idea that bZIP63 plays a role in energy signaling.
