Characterization of <i> <scp>A</scp> lternaria </i> species associated with potato foliar diseases in <scp>C</scp> hina

Abstract

The population structure of A lternaria species associated with potato foliar diseases in C hina has not been previously examined thoroughly. Between 2010 and 2013, a total of 511 A lternaria isolates were obtained from diseased potato leaves sampled in 16 provinces, autonomous regions or municipalities of China. Based on morphological traits and molecular characteristics, all the isolates were identified as A lternaria tenuissima , A . alternata or A . solani . Of the three species, A . tenuissima was the most prevalent (75·5%), followed by A . alternata (18·6%) and A . solani (5·9%). Phylogenetic analysis based on sequences of the internal transcribed spacer ( ITS ) region of ribosomal DNA (r DNA ) of representative A lternaria isolates showed that A . solani was distinct from the two small‐spored A lternaria species. Phylogenetic analysis of the partial coding sequence of the histone 3 gene divided the same collection of isolates into three main clades representing A . tenuissima , A . alternata and A . solani , respectively. The pathogenicity of the isolates on detached leaves of potato cv. F avorite did not differ significantly between the three species or between isolates from different geographical origins. The results indicate that the population structure of A lternaria species associated with potato foliar diseases differs from that reported previously in C hina. This is the first report of A . tenuissima causing potato foliar diseases in C hina.