Variation in telial formation of Puccinia striiformis in the United States

Authors: WAN, ANMIN - Washington State University; WANG, MEINAN - Washington State University; Chen, Xianming

Submitted to: American Journal of Plant Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/27/2019
Publication Date: 5/30/2019
Citation: Wan, A., Wang, M., Chen, X. 2019. Variation in telial formation of Puccinia striiformis in the United States. American Journal of Plant Sciences. 10:826-849. https://doi.org/10.4236/ajps.2019.105060.
DOI: https://doi.org/10.4236/ajps.2019.105060

Interpretive Summary: The stripe rust pathogen cause diseases on wheat, barley, and various wild grasses. The fungus produces urediniospores and teliospores on these primary or auxiliary hosts. Telial formation, which stops producing infectious urediniospores, is affected by various host and environmental conditions. However, it is not clear if variation exists among different isolates in the United States. To determine the differences in the pathogen population, 1,423 isolates collected in the United States from 2013 to 2016 were tested for telial formation under controlled conditions. The percentages of telial formation varied greatly among the isolates. Of the 1,423 isolates, 62.97% produced telia with the percentages of telial formation ranging from 1 to 95% under the test conditions. The formation of telia was significantly affected by the year and the month when the isolates were collected. The epidemiological regions or states, host plants (wheat, barley, and grasses), and races of the isolates did not significantly affect telial formation. However, significant effects on telial formation were observed by interactions between year and region, year and race, month and region, and among year, month, and region, as well as between year and month. The results showed that telial formation is a complex trait under the genetic control of the pathogen isolates for adaptation to different environments. The information may be useful in predicating pathogen population changes and selecting effective resistance genes for developing new varieties for control of stripe rust.

Technical Abstract: Puccinia striiformis, the causal agent of stripe rust in wheat, barley, and various wild grasses, produces urediniospores and teliospores on these primary or auxiliary hosts. Telial formation, which stops producing infectious urediniospores, is affected by various host and environmental conditions. However, it is not clear if variation exists among different isolates in the United States. To determine the differences in the pathogen population, 1,423 isolates collected in the United States from 2013 to 2016 were tested for telial formation under controlled conditions. The percentages of telial formation varied greatly among the isolates. Of the 1,423 isolates, 62.97% produced telia with the percentages of telial formation ranging from 1 to 95% under the test conditions. The formation of telia was significantly affected by the year and the month when the isolates were collected. The epidemiological regions or states, host plants (wheat, barley, and grasses), and races of the isolates did not significantly affect telial formation. However, significant effects on telial formation were observed by interactions between year and region, year and race, month and region, and among year, month, and region, as well as between year and month. The results showed that telial formation is a complex trait under the genetic control of the pathogen isolates for adaptation to different environments. Further studies are needed to identify genes involved in the formation of telia and the relationship of telial formation to the survival, aggressiveness, fitness, and evolution of the pathogen.