Different size and location of deletion generates different kinds of phenotypes In the course of plant evolution, genes are often duplicated in tandem, resulting in a functional redundancy. The analysis of function of these genes by developing double mutants might be difficult because they would be very tightly linked. Mutants of such tandem duplicated genes were investigated for their genotypes and phenotypes. There are reversely repeated two loci, which both codes for mRNA of glutelin production. There are various mutants that exhibit low glutelin contents isolated by SDS-PAGE [7, 32]. The mechanisms of low glutelin contents of mutants that have been studied suggest that the size and the position of deletions generate different characteristics of mutations. Some act as dominant genes or recessive genes, and those relationships between genotypes and phenotypes, etc. are provided as example below.