松针褐斑病菌毒素活性的生物检测

松针褐斑病菌毒素不仅能伤害湿地松、火炬松等寄主植物的幼苗、针叶、根及愈伤组织，对非寄主植物水花生、紫茎泽兰的叶片也有伤害作用。在试验的几种生测材料中，湿地松愈伤组织对毒素伤害最敏感，湿地松幼苗、幼针叶，火炬松幼针叶和紫茎泽兰叶片次之，湿地松幼根、老针叶，火炬松老针叶，水花生和小麦叶片最不敏感。根据生测材料的敏感程度及表现症状的特异性分析可知，用湿地松、火炬松幼苗和幼针叶作生测材料较好，比较针刺法、浸渍法和涂抹法等几种生测方法表明，用针刺法接种毒素效果最好，其反应速度快，用量少，症状明显。因此建议在松针褐斑病菌毒素的生物检测中，以湿地松或火炬松幼苗或幼针叶作为材料，采用针刺法。

Studies on the Bioassay of Toxins from Lecanosticta acicola Causing Brown Spot Needle Blight of Pines

Brown spot needle blight of pines is one of important pine diseases,which is caused by Lecanosticta acicola .It is confirmed that the fungi can produce toxic substances in its culture filtrate.The toxic substances ware called LA toxins.LA toxins could not only poison pine needles also the leaves of weeds.Various bioassay materials were treated with crude LA toxin to select sensitive material for the future study.The results indicated that seedlings and young needles of sensitive host(slash pine,lobollolly pine)were selected as bioassay materials for their sensitivities and reaction of the typical necrotic and yellow bands on needles.Such symptoms were similar to the symptoms of natural infection in the field and were different from other injuries.Old needles of pines and weed leaves were not sensitive to LA toxins.Compared with other two bioassay methods(soaking and smearing),the acupuncturing bioassay is the most suitable method because it just needs less toxin and can cause the evident symptom rapidly.