Tissue-specificity and developmental regulation of expression of Psr2 . Total RNA (10 μg) from different tissues was fractionated on a 1.2% agarose gel containing formaldehyde and probed with a Psr2 probe. (A) Lane 1, petal (one day before opening); lane 2, corolla (just opened flowers); lane 3, corolla tube (just opened flowers); lane 4, anther (tapetum degeneration stage); lane 5, pistil (tapetum degeneration stage); lane 6, anther (one day before opening); lane 7, healthy leaf; lane 8, stem; lane 9, root; lane 10, pistil (36 HACP); lane 11, stamen (36 HACP); lane 12, petal (36 HACP). (B) Densitometry measurements of lanes 7 to 12 relative to the stem signal. (C) RNA blots from petal tissue treated with 1 mM ethephon, at 0, 22, and 34 hours after treatment or with 50 μM methyl jasmonates (MEJA) at 0, 34, and 58 hours after treatment. Shortly before 0 time, the flower petals had opened.