Study the following cross showing self-pollination in $F_1$ generation,fill in the blank,and answer the question that follows:
Parents: $RRYY \times rryy$
(Round,yellow) (Wrinkled,green)
$F_1$: $RrYy \times$ ?
(Round,yellow)

(RRYY) In a dihybrid cross,the $F_1$ generation consists of heterozygous individuals with the genotype $RrYy$. Self-pollination of the $F_1$ generation involves crossing $F_1$ individuals with each other. Therefore,the cross is $RrYy \times RrYy$. The blank should be filled with $RrYy$.