Thanks, IAHFLYR for providing the link. And you are correct, Marriott is currently partnering with United Airlines, offering a higher status if you have Gold or Platinum Status at Marriott. However, you can use your Marriott Rewards Points to redeem airline tickets for American. See below link for additional details.
sorry to say Marriott doesn't have any cross level recognition program with AA. They do this, as others have noted with UA. The only way to do any sort of status on AA is to have flown miles, or get one of the branded AA credit cards that get you to a status level 9with some spend and a annual fee requirement).
Also, I suggest if you can, concentrate your flying on one airline and its partners to get the most status you can. I used to split my travel onto 2 different airlines, and really never made more than a minimal status level on each, then went to one airline, good or bad, and do all my flying on them.
Good luck in your quest