Influence of plant growth regulators,basal media and carbohydrate levels on the in vitro development of Pinus ponderosa (Dougl. ex Law.) cotyledon explants

Applications of in vitro screening techniques for Pinus ponderosa resistance to Peridermium harknessii could be beneficial in a tree breeding program. Plant growth regulators, basal media formula and carbohydrate levels were examined to determine the various effects each would have on excised cotyledon growth and development. Proliferating green callus was initiated from cotyledon explants on SH basal medium containing 4.4 M BA:5.4 M NAA and 1% sucrose. Subsequent subculturing onto LS medium supplemented with 44.0 M BA: 5.4 M NAA and 2% sucrose improved callus maintenance. The highest frequency of caulogenesis from cotyledon explants occurred on a modified GD medium containing 44.0 M BA: 0.054 M NAA and 4% glucose. The influence of nitrogen source, osmoticum and medium salt concentrations are discussed relative to callus initiation and caulogenesis.Abbreviations BA 6-benzyladenine - NAA -naphthaleneacetic acid - IAA indole-3-acetic acid - IBA indole-3-butyric acid - 2,4-D 2,4-dichlorophenoxyacetic acid - CD Campbell & Durzan - GD Gresshoff & Doy - LP Le Poivre - LS Linsmaier & Skoog - MC McCown - SH Schenk & Hildebrandt