Optimum tissue culture conditions for selection of resistance to Phytophtora cinnamomi in pine callus tissue.

The present experimentation compared the best nutrient medium, temperature, and growth hormones for callus induction and growth of various pine species from different seed sources with their effect on growth of Phytophthora cinnamomi. Callus tissues maintained on a modified Murashige and Skoog medium with 10(-5)M 2,4-D at 26°C in the dark optimized the expression of differential resistance when inoculated with hyphae of P. cinnamomi. High concentration of 2,4-D (5×10(-5)M) inhibited growth of P. cinnamomi.