It's hard to do that in the plot command, but the set command can do it:
h = plot(magic(3));
set(h,{'Marker'},{'+';'s';'o'})
The syntax is a little odd, isn't it? What's going on is that plot returned a 3x1 array of handles to line objects. The {} syntax to set says that I'm giving you a property name and an array of values, and I want you that property of each of the objects to the corresponding value.
Does that make sense?
