Identification of Species as Alternate Hosts for f. sp. and Determination of Existence of Sexual Propagation of the Rust Pathogen on Under Natural Conditions in China.

Many species have been identified as alternate hosts for f. sp. . Importantly, susceptible species are determined to play an important role in the occurrence of sexual reproduction, generation of new races of the rust pathogen. However, little is known about serving as alternate hosts for f. sp. and their role to commence sexual reproduction of the rust fungus under natural conditions. Herein, three species or subspecies, , subsp. , and , were identified as alternate hosts for f. sp. , and seven species were highly resistant to the rust pathogen. We recovered seven samples of f. sp. from naturally rusted plants. Totally, 54 single uredinium (SU) isolates, derived from the seven samples, generated 20 different race types, including one known race type, and 19 new race types. SNP markers analysis showed that all SU isolates displayed high phenotype diversity ( = 0.32) with a high Shannon's information index ( = 0.49). Analysis of linkage disequilibrium indicated an insignificant rbarD value (rbarD = 0.003,  < 0.1). As a result, all SU isolates are sexually produced, suggesting that f. sp. parasitizes susceptible to complete sexual reproduction under natural conditions. The role of in occurrence of wheat stripe rust are needed to study for management of the disease.