Well, first, you can use part whole grain flour. As per other substitutes, it is the special protein, gluten, in wheat that makes the dough kinda stringy, elast

Well, first, you can use part whole grain flour. As per other substitutes, it is the special protein, gluten, in wheat that makes the dough kinda stringy, elastic, and leads to nice texture when the gas bubbles from the yeast's metabolism stay inside the dough. With other substitutes, you might start to lose this. I don't know, I have not tried. The result will still of course be edible, but it might be less aerated, more dense. If it gets too dense, maybe the result will not be pleasing anymore.