The low G isn't about key, it's about range.
It annoys me that standard chromatic starts on middle C--
The G we are talking about is the open 4th string of the violin, it's not that low (I'm a guitar player, that note is the open 3rd string, and the guitar goes down another octave and a minor 3rd.
So I would say, as far as keys, G, C, F, Bb, Eb, Ab, Db, F# (although the low F# is missing!).
And probably D too, if you are used to it--certainly Dm, but that's either F or C, probably. Or D7, but that's G.
G