Evidence of Occurrence of Barley Crown Rust Caused by Puccinia coronata var. hordei and Sexual Reproduction of the Pathogen Under Field Conditions in China

Crown rust of barley, caused by Puccinia coronata var. hordei, was first reported by Jin and Steffenson in 1992, and the fungus has been reported only in the United States and Hungary. In China, stripe, stem, and leaf rusts have been reported on barley, but not for crown rust. Recently, a sample (HZJ0004) of rust collected from barley in Qilian county in Qinghai, China, appeareddifferentfromthe three rustsbasedoncolor, size, arrangements of uredinia and/or telia. Teliospores had crown-shaped appendages on the top. Based on the disease symptoms and morphology of urediniospores and teliospores, the fungus was identified as P. coronata var. hordei. Using the internal transcribed spacer sequences, the isolates HZJ0004 from barley and POR3 from buckthorn (Rhamnus sp.) were clustered in one clade with P. coronata var. hordei isolates from barley and Elymus repens but in a different clade from the isolate POC8 from wild oat and the varieties of P. coronata from oats and grasses. Atthe seedling stage, most of the tested cultivars of barley and rye were susceptible to P. coronata var. hordei isolates HZJ0004 and POR3, but the cultivars of oats, triticale, wheat, and most grasses of genera Aegilops, Brachypodium, Bromus, Calamagrostis, Deschampsia, Elymus, Festuca, and Phleum wereresistant, indicating theirhost specializationonbarley. Toourknowledge, this is the first report of crown rust on barley in China.

Automated summary

This study reports the first occurrence of crown rust on barley in China, and reveals different levels of host resistance to the pathogen among different plant species.