两种唐松草鉴定为小麦叶锈菌的转主寄主

 引起小麦叶锈病的小麦叶锈菌(Puccinia triticina)是转主寄生菌,其转主寄主主要为唐松草属(Thalictrum)种类,也包括扁果草属(Isopyrum), 牛舌草属(Anchusa), 铁线莲属(Clematis)和蓝蓟属(Echium)的个别种类。然而,迄今,中国仅有亚欧唐松草和瓣蕊唐松草被报道为小麦叶锈菌转主寄主。本文对采集于陕西的东亚唐松草(T. minus var. hypoleucum)、甘肃的贝加尔唐松草(T. baicalense),通过人工接种小麦叶锈菌确定它们是否能够作为小麦叶锈菌的转主寄主。同时,本文作者收集自然条件下贝加尔唐松草组织上受侵染产生的锈子器样品,通过其ITS区序列分析以确定小麦叶锈菌的有性循环是否在田间条件下发生。结果表明,小麦叶锈菌的担孢子均可侵染东亚唐松草和贝加尔唐松草,完成其性子器和锈子器阶段,产生的锈孢子可侵染感病小麦产生夏孢子堆,从而证实东亚唐松草和贝加尔唐松草均可作为小麦叶锈菌的转主寄主。来自贝加尔唐松草22个锈子器样品的ITS区序列比对,表明其与NCBI网上提交的小麦叶锈菌享有95%~96%的序列同源性。由此推测,自然条件下,中国小麦叶锈菌可能侵染感病唐松草完成有性循环。

Identification of TwoThalictrum Species as Alternate Hosts for Puccinia triticina, the Wheat Leaf Rust Pathogen

Puccinia triticina, the cause of wheat leaf rust, is a heteroecious parasite. Its alternate hosts include mainly Thalictrum spp., and several species in genera Isopyrum, Anchusa, Clematis, and Echium. So far, only two Thalictrum species, T. minus L. and T. petaloideum L., have been reported as alternate hosts for the rust pathogen in China. In the present study, two new species of Thalictrum, T. minus var. hypoleucum and T. baicalense, collected from Shaanxi and Gansu provinces were tested their susceptibility to P. triticina through artificially inoculation to determine as alternate hosts for the rust fungus under controlled conditions. Simultaneously, we collected aecial samples from naturally infected tissues of T. baicalense plants and tested them to determine whether they were P. triticina by sequence alignment of ITS regions and sexual cycle of the rust fungus could occur in field. The results showed that T. minus var. hypoleucum and T. baicalense can infect the two Thalictrum species to complete their pycnial and aecial stages, and that aeciospores can infect susceptible wheat cultivar to produce uredinia, indicating T. minus var. hypoleucum and T. baicalense serve as alternate hosts for P. triticina. Twenty two aecial samples collected from naturally infected leaves of T. baicalense were identified as P. triticina as they had 95%-96% sequence homologies with the ITS region sequences of P. triticina submitted in the NCBI database. This hinted P. triticina could infect susceptible Thalictrum spp. to complete sexual cycle under natural conditions in China.