Environmental conditions affecting the germination of Puccinia hemerocallidis urediniospores

Daylily ( Hemerocallis spp) rust caused by Puccinia hemerocallidis is a common disease that has become a global problem. This study identified and characterized the causal agent of daylily rust in east China. Based on the internal transcribed spacer (ITS) sequences, a phylogenetic tree of the P. hemerocallidis from China and other geographical regions was constructed, and the result showed that P. hemerocallidis from daylilies in east China grouped with other P. hemerocallidis isolates collected from North-, Central-American and Europe. In addition, the effects of incubation condition, temperature, and light on urediniospores germination were investigated in vitro. The results showed that the P. hemerocallidis urediniospores could germinate at 10–40 ℃ under light intensity of 10–100 Klux, but they hardly germinated at 5 ℃. W-WA medium (water agar medium covered with sterile water) was the most suitable in vitro germination substrate, combined with the temperature of 20–30 ℃ and light intensity of 40–70 Klux. The results of this study provided a basis for understanding the biology of the causal agent of daylily rust disease.