Figure 3. Sugar represses miR156 expression.
(A) Northern blot of miR156 in 12-day-old plants treated with 10-mM glucose (Glc), fructose (Fru), mannitol (Man), sorbitol (Sor), and O-methyl-glucose (OMG). U6 was used as a loading control. Only Glc and Fru reduce miR156 expression. (B) Northern blot of miR156 in 12-day-old plants treated for 4 hr with 10 mM of the indicated substances. The effect of glucose on miR156 expression is blocked by cycloheximide, a protein synthesis inhibitor. Man: mannitol; Glc: glucose; CHX: cycloheximide. (C) Northern blot of miR156 in 12-day-old ch1-4 plants treated with different amounts of glucose. 0.5 mM produced a 50% reduction in miR156, and higher amounts of glucose did not produce a further reduction. (D) 5-mm primordia of leaf 6 from pSPL9::SPL9-GUS and pSPL9::rSPL9-GUS plants, cultured for 8 hr in media containing 10 mM of different sugars. Scale bar = 1 mm. (E) Exogenous sucrose significantly accelerates abaxial trichome production in wild-type plants. Asterisk indicates significant difference (p<0.01; n = 12; error bars indicate SEM).