Is it acceptable for a company to patent the DNA of a naturally occurring plant or food (that some argue should be available for the benefit of all) simply because they were the first to make the...

Is it acceptable for a company to patent the DNA of a naturally occurring plant or food (that some argue should be available for the benefit of all) simply because they were the first to make the patent application? Does that answer change if that process or piece of knowledge has existed in local folklore or customs for many generations?