Normalized Expression (∆∆Ct) of a target gene was calculated as follows: ∆Ct (drought) = Ct (target gene, drought) – Ct (U6 snRNA, drought) ∆Ct (control) = Ct (target gene, control) – Ct (U6 snRNA, control) Therefore, ∆∆Ct = ∆Ct (drought) - ∆Ct (control) (Sample loading differences are removed when relative quantity of a target gene is normalized by a relative quantity of the U6 snRNA reference gene.) Normalized fold change = 2 -∆∆Ct