How old are your daughter and her teammates? That definitely makes a difference in how to handle things.
Agree with poster above that bullying can be overlooked if the kid doing the bullying has high gym potential...it sort of sucks.
I think for younger kids, the best you can do beyond talking to the coaches is to try and help your kid find strategies handle it. Like calmly refuting the lie ("I can hear what you are saying about me and it's a lie." and then walk away), or calmly asking the girl in front of others and in front of the coach to please stop talking about her, or to speak to the coach herself. I will say that if you talk to the coach yourself, ir seems to work better if you don't name names. Just say that your child has mentioned feeling bullied and hearing another child spread lies about her.
If your child is older and a higher level, truth is that she may just need to defend herself and keep her chin up. Make the choice not to let someone else decide her happiness. Easier said than done, I know...