Greg Anderson, Barry Bonds' weight trainer and a confessed steroid dealer, has been subpoenaed to testify in a widening investigation into whether the Giants slugger lied under oath in 2003 when he denied using banned drugs, The Chronicle has learned. Anderson has been summoned to appear before a federal grand jury in U.S. District Court in San Francisco as part of a probe into whether Bonds committed perjury when he told another grand jury that he had never used steroids, said two sources familiar with the case. In addition to Anderson, the grand jury will seek testimony from James Valente, another co-conspirator from the BALCO case, according to two sources.