Development of RNA extraction protocol. A: RNA extracted from Arabidopsis leaves. Lane 1, RNA extraction using Logemann et al.'s protocol . Lanes 2 and 3, RNA obtained by transfer through a plasmid DNA extraction column (QIAprep Spin Miniprep Kit). Lanes 4 and 5, RNA obtained from transfer through an RNA collection column (RNeasy). EtOH, 96% ethanol; M, DNA 1-kb ladder. B: RNA yield following extraction in 8 M guanidine hydrochloride buffer and 0.5 volume of 96% EtOH and transfer through a plasmid DNA extraction column (QIAprep Spin Miniprep Kit), followed by 2-3 washes in: (1) RW1 × 2 and RPE (RNeasy Plant Mini Kit), (2) 3 M Na-acetate and 70-75% EtOH; (3) two washes with 96% EtOH; (4) 3 M Na-acetate and PB (QIAprep); (5) two washes with PB. RNA yield was measured spectrophotometrically.