The Role of Your Previous Supervisor
In your grant application, try to dissociate your research program from that of your previous supervisor. However, this may not be entirely possible, and it may be especially difficult for basic biomedical scientists who are bringing technologies from their previous supervisor. In that case, cite your previous supervisor in your grant application, where appropriate.
A positive letter of reference from a previous supervisor can be very influential with the review committee-particularly if the letter describes how your research program is distinct from that of the supervisor.