* Saint Laurent relives 1990s rock-n-roll Seattle
* Stella McCartney plays with pinstripes, voluminous shapes
* PPR seeks young YSL buyers, Stella's expansion in Japan (Recasts with Saint Laurent show)
By Alexandria Sage
PARIS, March 4 (Reuters) - With the spirit of 1990s grunge pervading the runway, it wasn't your mother's YSL at the Saint Laurent fashion show in Paris on Monday night.
New designer Hedi Slimane channelled the Seattle scene in the era of grunge-rock band Nirvana. Models in ratty Courtney Love hairdos moved sullenly down the catwalk, with shapeless plaid lumberjack shirts covering babydoll dresses cut up to there.
Certainly, Slimane played with many of the famous label's elegant design motifs that recurred throughout the decades - sharp tailoring on jackets, halter tops with exposed backs and demure white Peter Pan collars with black bows.
But it was perfectly apparent from the Fall/Winter 2013/2014 collection that Slimane and Saint Laurent's owner, luxury group PPR, are searching out younger clients, born too late to remember the many innovations of founder Yves Saint Laurent.
The ready-to-wear shows in Paris - part of an 11 billion euro ($14.3 billion) French industry - largely influence what will be seen on fashionable backs around the world the coming season.
Slimane quickly put his mark on the label after being appointed to head it last March, truncating the ready-to-wear brand's name to howls of protest from loyal fans.
But on Monday, the brand boasted its new Hollywood cred with Kirsten Dunst of "Spider-Man," in the front row, as well as French actress Catherine Deneuve, former muse to Saint Laurent.
Rocker leather jackets appeared over and over, as did leather ankle boots. Slimane even sent out Paddington coats and suede and fleece coats that looked like they could have been found on a thrift store rack.
Underneath the heavy coats and plaid shirts, one could barely make out what appeared to be sweet little silk dresses that Deneuve might have worn in the 1967 film "Belle de Jour," albeit much more thigh-baring.
The brand last month posted a 28.8 percent hike in 2012 revenue on a comparable basis, with expanding operating margins.
Growth was seen from all of the brand's regions but especially in emerging markets like Japan, where revenue rose 46.7 percent.
"WALK LIKE A MODEL"
Also on Monday, British designer Stella McCartney opted for exaggerated volume, presenting contrasting pinstripes, voluminous coats and elongated skirts.
Interrupted by jolts of amethyst on a boucle coat and a body-covering silk dress, the mostly grey-and-black collection imparted a structured, masculine feel in line with McCartney's tomboy sensibility.
The Stella McCartney brand showed a "sharp increase in profitability" in 2012, according to part-owner PPR, which does not break out its results.
A key priority for the brand this year is expanding its store base in Asia, which already includes outlets in Japan, Thailand, South Korea and Singapore.
Underscoring the stature of the young British designer, U2's Bono, wearing his signature sunglasses, attracted a throng of photographers, as did American actress Jessica Alba, who gushed over the opulent Opera Garnier setting.
The show was delayed for 30 minutes by the tardy arrival of Paul McCartney, the designer's father.
"Walk, walk, walk like a model," the former Beatle was overheard saying to his wife Nancy Shevell as they walked down the runway to take their seats.
After the show, he called his daughter "the best".
"I thought it was beautiful. Very strong, very clean," he told Reuters TV. ($1 = 0.7687 euros) (Additional Reporting By Leona Liu, Editing by Belinda Goldsmith and Michael Roddy)