By Chris Gallagher and Caroline Stauffer

RIO DE JANEIRO (Reuters) - U.S. team coordinator Marta Karolyi could not have ended her gymnastics coaching career on a better note as two of her students, Simone Biles and Aly Raisman, claimed gold and silver in Tuesday's floor exercise.

Karolyi and her husband Bela, who count the first ever gymnast to score a perfect 10, Nadia Comaneci, among their many pupils, are credited with turning the United States into a gymnastics powerhouse after defecting from Romania in 1981.

"We ended it on a good note for Marta," Biles said after winning a record-equaling fourth gold at the Rio Games. "I think we put the cherry on top, me and Aly, finishing floor as well as we did."

The Karolyis, who run a gym in Houston, retired from coaching after the 1996 Olympics, though Bela was called back in 2000.

Marta took over in 2001, overseeing U.S. team silvers in 2004 and 2008 followed by back-to-back team golds in London and Rio.

They cultivated some of the best-known gymnasts that have competed for the U.S., such as Mary Lou Retton, Kerri Strug and Dominique Moceanu.

"I went after Simone so I was Marta's last gymnast ever and I knew I had to do good for her," Raisman said about Tuesday's floor exercise.

"I said, 'I'm your last gymnast ever' and she (Marta) said, 'I don't want to think about it, I'm going to start crying'."

Though often in the background, Raisman, the U.S. team captain, has accumulated six Olympic medals from London and Rio, a greater number than her more celebrated team mates Biles and Gabby Douglas.

Douglas, who like Raisman competed in London four years ago, has three medals while Biles tied the record of four golds in a single games in Rio and earned bronze on the balance beam.

"I used to look up to her, I remember in 2012 watching her and I was just like, I want to be just like her," Biles said of Raisman.

Romania earned no medals in gymnastics at the Rio Games, the first time since 1972 they have left an Olympics empty-handed in a sport they have often dominated.

(Reporting by Chris Gallagher and Caroline Stauffer; Editing by Mark Lamport-Stokes)