马铃薯及番茄晚疫病菌的核糖体DNA-ITS区段序列分析*

 取3个不侵染马铃薯的番茄晚疫病菌菌株和3个不侵染番茄的马铃薯晚疫病菌菌株，以及2个可交叉侵染马铃薯和番茄的菌株，提取DNA全基因组后， 用引物ITS1和ITS4进行扩增，得到约850 bp左右的扩增产物并进行测序，比较同源性，结果显示这些菌株的全基因组DNA序列与Genebank上登录的3个序列AF228084，AF228083，AY269995.1的同源性均为100%。3个番茄菌株之间的同源性大小为98.22%,3个马铃薯菌株之间的为99.52%，较番茄菌株的同源性高。不可交叉的两类菌株间的同源性为98.28%，可交叉侵染的番茄菌株和马铃薯菌株之间的同源性为99.17%，比不可交叉侵染的菌株间的同源性高,说明相似的序列使得生物学特性也很相似,反之,同源性有差异的,在生物特性上也表现出一定差异。

Analysis on Sequence of Ribosomal DNA-ITS of Phytophthora infestans from Potato and Tomato

3 isolates of P.infestans from tomato that couldn't infect ptato,3 isolates from potato that couldn't infect tomato and 2 isolates of P.infestans that could infect both tomato and potato was amplified using polymerase chair reaction(PCR) and the universal primers internal transcribed spacer ITS 1 and ITS4.PCR products wee an approximately 850 base bair and checked the sequences. The sequences of ribosomal DNA-ITS of 8 isolates were compared with 3 sequence logging in genebank and their homegenies were 100%. The homologous character of 3 isolates from tomato were 98.22% and 3 isolates from potato were 99.52%. The homogenies of 2 isolates that couldn't cross infect potato and tomato were 98.28%. The homogenies of 2 isolates that could infect tomato and potato were 99.17%,it was higher than isolates that couldn't cross infect. The resembling sequences leaded to the resemble biological characters. On the contrary, the different sequences leaded to different biological characters.