siRNA absent from cell secondary siRNA absent from cell FYPO:0007010 secondary small interfering RNA absent from cell secondary siRNA absent from cell during vegetative growth secondary siRNA absent from cell during mitotic cell cycle midori 2019-07-31T12:03:41Z A cell phenotype observed in the vegetative growth phase of the life cycle in which the amount of secondary siRNA measured in a cell is too low to detect. Secondary siRNAs are sequences homologous to regions 5' and 3' to the initial siRNA, and their production amplifies the primary siRNA signal.