A popular school committeewoman who has weathered the political storms of court-ordered desegregation here yesterday entered the race for the Massachusetts Democratic senatorial nomination to challenge Republican Edward W. Brooke, the only black in the Senate.

Katherine Sullivan-Alioto's announcement came on the heels of Brooke's disclosure Friday that he "made a misstatement" about his finances in a court deposition filed during the recent bitter divorce from his wife.

However, Sullivan-Alioto, wife of the recently divorced former mayor of San Francisco, Joseph Alioto, and daughter of New England Patriots football team owner William Sullivan, denied Brooke's statement prompted her candidacy.

"I'm running because I've spent the last 12 years of my life on the front lines of one of the major social revolutions in our history; it has a way of deepening your insights," said Sullivan-Alioto, a former Boston public school teacher and five-year veteran of the Boston School Committee, which tried to fight the 1974 federal desegregation order.

Sullivan-Alioto, who has been mentioned as a possible candidate for mayor of Boston, has been one of the city's top vote-getters in recent years. Although opposed to school busing to achieve integration, she urged residents to cooperate with the federal plan.More vocal antibusing politicians like city councilors Louise Day Hicks, John Kerrigan and school committee member Elvira (Pixie) Palladino were swept from office last years.

Sullivan-Alioto becomes the fifth candidate to announce so far for the Democratic nomination in a race that is beginning to look more like the Boston Marathon than a primary contest.

The race, one of the liveliest in the nation, has been dubbed "Looney Tunes Presents," by another Democratic Senate candidate, Elaine Noble, the only avowed lesbian legislator in the country.

Also running or expected to run on the Democratic side are Rep. Paul Tsongas, state Rep. Michael J. Connolly, Brandeis Professor Ruth Morgenthau, former Boston mayor John Collins, and former Republican Howard Phillips, the man who tried to dismantle the national proverty program for Richard Nixon.

"What we're looking at is the critical mass factor - the algebra of Massachusetts politics." Said state Sen. Chet Atkins, chairman of the Massachusetts Democratic Party. "As more people get into the race, there's a likelihood that even more will enter the field because with more people the individual candidate needs a smaller percentage of the vote to win."

Atkins predicted Brooke's disclosure would not be the "sole factor" in pushing additional candidacies, but "it has helped accelerate the process for a lot of people who have been thinking about getting into the race."