Chennai, Jun 3 (IANS): Actress Keerthy Suresh, who plays legendary actress Savitri in upcoming multilingual biopic "Mahanati", will have to gain weight to shoot some important portions of the film which went on the floors last week.

"Keerthy has already started shooting. She is currently shooting the portion where Savitri was a youngster. She is required to gain weight to play Savitri in her prime when she had serious weight issues but was still loved by audiences," a source from the film's unit told IANS.

Being directed by Nag Ashwin, the film - to be made in Telugu, Tamil and Malayalam - also stars Samantha Ruth Prabhu and Dulquer Salmaan.

While Samantha plays a key role, Dulquer will reprise veteran actor Gemini Ganesan, who was married to Savitri.

"It'll be a magnum opus period film set in the golden era. With massive set pieces, the film will be unlike anything we've explored in Indian cinema," Ashwin had told IANS.

Born on January 4, 1936, Savitri made her acting debut in 1950 Telugu-Tamil drama "Samsaram", and went on to star in several classics such as "Devadasu", "Missamma", "Penin Perumai", "Pasa Malar", "Bhale Ramudu", "Thodi Kodallu", "Mayabazaar" and "Gundamma Katha".

Meanwhile, on Saturday, Keerthy made her debut on Instagram.