Study On Mutation Breeding Of Paecilomyces Lilacinus IPC Strain

Meloidogyne distributes cosmoplitanly,causes serious damages on a widerange of hosts.The lost is about 10%,the most is more than 75%,and thedamaged plants become more susceptible to fungi and bacteria.Paecilomycceslilacinus (Thom) Samon is an ordinary fungi within some plants'root system;meanwhile,it is also a valuable biocontrol fungi,predator of insects andnematodes.Egg parasitic rate on Meloidogyne incognita is 60%~70%. Recently,there were researched on biocontrol of nematodes with P. lilacinus,goodisolates were screened and put to production.but the natural isolates have lowegg parasitic rate,don't perform good in production.So isolates mutation is theparamount. The study includes (1) treats spores of IPC with Ultraviolet andchemicals,screens good isolates;(2) detects the genetic diversity of the mutatedisolates with Randomly Amplified Polymorphic DNA(RAPD).(3) studies theconditions for the formation and regeneration of protoplast,and inducesprotoplast by UV radiation ,makes basis for the mutation,fusion and transformof protoplast to screen isolates and optimizes characteristics. The main resultsare as follows: 1. The Paecilomyces lilacinus IPC was induced to mutation through thetreatment of spores with UV and 3 mutation chemicals. All methods producedmutated isolates that are more parasitic to the eggs of Meloidogyneincognita,the best is UV radiation treatment. 7 mutated isolates of UV-307,UV-309, UV-14,UV-21,HN-402,HN-404 and HN-407 are 15%~24.28% moreparasitic rate than IPC.The cultural characteristics of 7 isolates have changed. 2. In the mutation of P. lilacinus to parasite eggs of M. incognita theamount and activity of chitinase was first taken to be standard forscreening.The study found this method can screen positive mutatedisolates,reducing the workload.The activity of isolates was also taken as screenstandard.The rate of positive mutation was 77.3%. 3. The genome DNA of IPC and its 15 mutated isolates was analyzed by - 3 -淡紫拟青霉菌 IPC 菌株诱变育种研究RAPD assay with 6 RAPD primers.A total of 114 polymorphic bands wereamplified.The polymorphism detection rate was 83.3%.The cluster analysis ofthe RAPD profiles by using UPGMA displayed that the studied isolates havegenetic polymorphism,the RAPD can detect the mutation and its degreequickly and accurately. 4. The effects of such factors as age of mycelium, osmotic stabilizers,enzymes and their concentration, enzymatic time and regeneration medium onthe formation and regeneration of P. lilacinus protoplasts were studied. Theoptimum condition are mycelium aged 20h, 5mg/mL snailase,0.8mol/L NaClas osmotic stabilizer, and 2~3h of enzymatic time .Regeneration percentage ishighest when the protoplasts are plastered on 0.5% agar medium with 0.6mol/LNaCl.The protoplast yeild of P. lilacinus IPC have reduced 106~107/mL,theregeneration rate was more than 20%. 5. The protoplast of Paecilomyces lilacinus IPC was irradiated by UVradiation.The induced fatality rate of protoplast reached 100% by UV of 2minutes.30 seconds of UV should be used for the screening of isolates.Protoplast is more susceptible to UV than spores.