Although varieties abound, wheat can be more simply considered as either hard or soft, hardness being a measure of the kernel’s resistance to crushing.
All wheat originally was soft-kerneled. And there is, so far as we know, no evolutionary advantage to either the hard or the soft trait.
But clearly, somewhere along the line, that section of genetic material that determines the hardness of the kernel underwent a random mutation. Specifically, the Puroindoline a or Puroindoline b genes, which have long been a focus of Craig Morris’s research.
In order to understand the hard/soft divide, Morris, a plant physiologist, suggests that we consider the … » More …