RIO DE JANEIRO (AP) — Joao Gilberto, a Brazilian singer, guitarist and songwriter considered one of the fathers of the bossa nova genre that gained global popularity in the 1960s and became an iconic sound of the South American nation, died on Saturday, his son said. He was 88.

Joao Marcelo said his father had been battling health issues though no official cause of death was given. "His struggle was noble. He tried to maintain his dignity in the light of losing his sovereignty," Marcelo posted on Facebook.

A fusion of samba and jazz, bossa nova emerged in the late 1950 and gained a worldwide following in the 1960s, pioneered by Gilberto and Antonio Carlos Jobim, who composed the iconic Girl From Ipanema that was sung Gilberto, his wife Astrud Gilberto and others.

In 1961, Gilberto finished the trilogy of albums that would make bossa nova known around the world: "Chega de Saudade," ''El Amor, La Sonrisa y La Flor, and "Joao Gilberto."

"It was Joao Gilberto, the greatest genius of Brazilian music, who was the definitive influence on my music," singer Gal Costa wrote on social media. "He will be missed but his legacy is very important to Brazil and to the world."

Born in Bahia in northeastern Brazil, later moved to Rio de Janeiro. His 1964 album Getz/Gilberto with U.S. saxophonist Stan Getz sold millions of copies, won several Grammy awards and popularized bosso nova. Over his career he won two Grammy awards and was nominated for six.

Journalist and bossa nova scholar Ruy Castro called the death of Gilberto a "monumental" loss.

"He managed to create a mystique about him abroad, being who he was and not even speaking English," he told the Globo television station.

As well as Marcelo, Gilberto is survived by two other children, Bebel and Luisa.

Singer Daniela Mercury called Gilberto a "genius who revolutionized popular Brazilian music. He taught us now to sing in the most beautify way in the world."

"Go in peace, maestro," she wrote.