To make room, the team option right-handed reliever Evan Marshall to Reno.
Nuno was 3-2 with a 3.23 ERA in six starts with the Aces.
Marshall was 0-2 with a 6.08 ERA in 13 appearances with the Diamondbacks. He had struggled for most of his time with the big league club but had been better in recent outings.
Manager Chip Hale says Marshall seems to have started to figure out what his problems are and going to Reno will allow him to continue to work on them.