Isolation and Primary Identification of Leaf Rust on Black Cottonwood (<i>Populus deltoides</i>) at the South of China

To explore the species of pathogen of leaf rust on black cottonwood ( Populus deltoid e s ) at the south of China, in this study, leaf rust spores were isolated and identified on P.deltoides in JiangSu Province(NanJing,SiHong,SiYang), AnHui Province (HeFei) and HuBei Province (ShiShou). Totally eleven isolates (three in NanJing, four in SiYang, two in HeFei, one in SiHong, one in ShiShou) were obtained by leaf single conidia isolation method. Through scan electron microscope (SEM), the spores of the length, width, thorn distance and diameter of bald surface of each segregation line were found to be largely different between them ( p <0.05). By ITS and LSU sequencing, the urediniospores of SY92, SY39, SY40, SY16, NJ10, NJ30, NJ65, HF58 and HF59 were similar with M.larici-populina , the urediniospores of SH48 and SS101 were similar with M.medusae . According to molecular clustering, the urediniospores from NanJing, SiYang and HeFei were categorized into M.larici-populina and those from SiHong and ShiShou were classified into M.medusae . Intriguingly, M.medusae found is at first recorded at the south of China. Our study provides an important reference for further research on the pathogen of leaf rust on P. deltoides at the south of China.