Figure 3.

Northern blot of hypocotyl RNA from loblolly pine seedling cuttings. A, RNA was extracted from the base of hypocotyl cuttings and placed in either distilled water (−) or distilled water plus 10 mm IBA (+) for the times indicated. One microgram of total RNA was electrophoresed in a 1% agarose gel, northern blotted, and hybridized with the clone pDD21.4.1. After exposure to x-ray film, the filter was erased and rehybridized with an 18S rRNA probe from eastern larch and with a loblolly pine partial cDNA clone for actin (accession no. AF085331), as described by Hutchison et al. (1990). B, RNA extracted from hypocotyl cuttings at the times indicated in an independent rooting experiment. Four micrograms of RNA was used per sample, and the filter was hybridized with the larch 18S rRNA probe and the expansin probe.