Guthrie talks in this video about minor modes to experiment with while improvising over a minor chord or key. He spends the majority of the video showcasing the phrygian mode, which has a distinct sound that can make it hard to use, but can add a lot of interesting notes to an improvisation.
A Dorian
Dorian: 1 2 b3 4 5 6 b7
The A Dorian mode is the second mode of the G Major scale. This means A Dorian contains all the notes of the G Major scale, but starting and ending on A.
The Dorian mode is often substituted for the regular minor scale (Aeolian mode) during improvisation. The Phrygian mode can be hard to use while improvising over a minor chord or chord progression, but can sound very interesting and distinctive.