COB 2 - There are three main genes that control sweetness in corn, the su1, sh1 and se1 genes. These genes can involve gene products like amylases, or other enzymes that can affect amylases. The su 1 gene is what this cob was looking at. This sweet mutation is recessive, and as explained in the lab, you were counting an F2 cob. You can expect a phenotype ratio of three starchy (SU_) for every sweet (susu) kernel. COB 2 QUESTION 1.) What are amylases, and how would they be involved in a trait change from starchy to sweet..