The Colts reported signing of WR Nathan Palmer could mean Austin Collie's knee injury is severe. (Getty Images)

The Indianapolis Colts have reportedly signed wide receiver Nathan Palmer to its 53-man roster, according to 49ers RapidReporter Kyle Bonagura.

And, later, from the Colts beat reporter at the Indianapolis Star:

Palmer told CBSSports.com's Kyle Bonagura that he didn't know about the deal until Monday morning.

"I was getting up to get ready to go work out this morning and had a missed couple calls from my agent and once I called him back he was telling me there was good news and bad,” Palmer said. “First he told me I was going home and I thought I'd been cut or released. Then he said I'm going home because I'm going to play for Indy.”

Palmer also said that he was excited about the opportunity to play with Andrew Luck.

“Anytime you can go in and work with a young quarterback, it's a chance to build good camaraderie,” Palmer said. “I'm excited to work with [Luck].”

Chances are wide receiver Austin Collie's knee injury could have him sidelined for an extended period of time, at best, and it has been speculated that Collie's career as a Colt could possibly be coming to an end.

Collie injured his knee Sunday after recording his first catch of the season. He had missed the first two games after suffering a concussion in preseason. An MRI will be performed Monday to determine the seriousness of the knee injury. Collie was carted off the field after being helped to the sideline.

Palmer played in college at Southern Illinois, alongside Indianapolis backup quarterback Chandler Harnish.

For more up-to-the-minute news and analysis from Colts blogger Evan Hilbert, follow @CBSColts.