Why do avirulence genes of the rice blast fungus undergo multiple translocation?-A hypothesis that crabgrass plays a role as their repository

我们研究了无毒基因在Pycucularia种群中的分布。AVR-Pita 2是与Pita抗性基因对应的AVR-Pita无毒基因家族的同源物，在稻瘟病菌的黍属分离物和稻瘟病菌的马唐属分离物中发现。AVR-Pii 2是AVR-Pii家族的一个同源基因，对应于Pii抗性基因，存在于稻属的稻瘟病菌和稻瘟病菌的稗草属菌株中，AVR-Pii 3是AVR-Pii家族的另一个同源基因，存在于小麦属的稻瘟病菌和稻瘟病菌的稗草属菌株中。

We examined distribution of avirulence genes in Pycucularia populations. AVR-Pita2, a homolog of the AVR-Pita avirulence gene family corresponding to the Pita resistance gene, was found in Panicum isolates of P. oryzae and Digitaria isolates of P. grisea. AVR-Pii2, a homolog of the AVR-Pii family corresponding to the Pii resistance gene, was found in Oryza isolates of P. oryzae and Cenchrus isolates of Pyricularia sp. AVR-Pii3, another homolog of the AVR-Pii family, was present in Triticum isolates of P. oryzae and Cenchrus isolates of Pyricularia sp. These results suggest that horizontal transfer of avirulence genes are not rare event in the blast fungi.