Abstract:Based on shoot-tip multiplication technique, the application of in vitro selection of black peppersomaclones resistant to foot rot disease caused by fungus Phytophthora capsici was carried out using a large-leaf variety Daye (Lampong Type) which is widely cultivated in Hainan but highly susceptible to P. capsici as explant resources. The results demonstrated that sterilization methods significantly influenced on the toxicity of the culture filtrate of P. capsici. The fungal filtrate toxicity could be maintained using filtrate sterilization by addition of the fungal filtrate into selective medium instead of autoclave sterilization． The survival rate of shoot tips and multiple shoots decreased with the increasing concentrations of the fungal culture filtrate． Some cultures blackened and died finally, and some formed calli or remained dormant．After 2 subcultures onto the same selective medium， microshoots were rooted in vitro and tran sferred to the greenhouse conditions for screening the resistance to fungus P. capsici．The plants exhibited no external symptoms of the disease during three successive times of resistance assay once two weeks were considered to be resistant． As the concentrations of fungal culture filtrate increased，the total number of regenerated plants obtained declined but the frequencies of plants resistant to capsici increased．1(1.54％)，4(20.OO％) and 3(42.86％) disease resistant somaclonal variants were obtained at concentration of 25％ ，50％ and 75％ fungal culture filtrate as selective agents， respectively，with the total number of 8 plants resistant to P. capsici.