There's one that I have heard of - Lyon Arboretum. I'm sure there are many more. There are so many endangered species in Hawai'i that are either still in existance today because of tissue culture, or whos existence depends on tissue culture.

Which island? They teach it at Honokaa High School, if you want to learn how. You may have to ask the AG teacher if you can sit in on his classes, though! ;)

There's a few labs on the Big Island, although I don't know their names. I could ask the AG teacher, he would know if you want a tissue culture lab on Hawaii instead of Oahu.