Prosecutors allege Bo received a large sum of money and property from his wife and son, Bo Guagua, that came from businessman Xu Ming, the official Xinhua News Agency reported.
They also presented testimony indicating Bo was aware of a French Riviera villa bought for his family by a tycoon, and of demands for compensation by British businessman Neil Heywood, later slain by Bo's wife, the New York Times reported.
The imprisoned Gu said her husband didn't promise any political favors to Xu Ming, who provided her with millions of dollars in gifts, the Los Angeles Times reported.
Gu was asked repeatedly about the money and gifts she received from Xu, and if her husband knew about them.
She did not clearly implicate her husband, the Times said.
"I think I should have told him," she said. "It is the type of thing he should have known."
She also pointed to her personal relationship with Xu.
"Xu Ming and I were old friends. ... Our relationship is rather deep," she said in the videotaped testimony. "We felt he was an honest person, well-mannered. He didn't have the airs of a businessman."
The 64-year-old Bo, who had been in line for top leadership in the communist country before his fall from grace last year, denied the bribery charges Thursday on the opening day of his much-awaited trial in Jinan in east China's Shandong province.
The trial amid tight security remained closed to foreign journalists and details of the proceedings were being relayed through microblog posts by the court.
Bo denied taking a $180,000 bribe from businessman Tang Xiaolin. He also denied taking a $3.4 million bribe from Xu Ming. The indictment against Bo alleges the bribes were for helping related parties and individuals to obtain preferential quotas to import cars and work on petrochemical projects.
CNN, quoting the court, said Bo told the court he had earlier accepted the bribery charge "unwillingly" when he was being investigated by a party disciplinary commission. "But at that time, I didn't know the details mentioned above," he was quoted as saying.
"Bo's attitude [at the trial] was to flaunt his cunning and use a hundred kinds of denial," the Communist Party newspaper The Guangming Daily commented on its website Friday.
Bo, a former member of the country's top-ruling Political Bureau of the Chinese Communist Party's Central Committee and former party chief of Chongqing province, is also charged with corruption and abuse of power. Until his court appearance, Bo had not been seen in public since his arrest in March 2012.
Bo's downfall began last year following a series of scandals that included his equally prominent lawyer wife being implicated in the killing of Heywood.