No, she will not grow out of it. You may have good luck with training and behavior modification so that they get along better but they do not just grow of things like this.
Also, she is only 1 year old and is not yet physically or emotionally mature and it will likely continue to get worse and there may be more challenging. You need to focus on making sure their relationship is good and without tension. Stop the younger one from guarding and don't put the older one in position to have to (or be allowed to) correct the younger one.